Sunday, December 16, 2012
HAYMAKING
Haymaking turns green, perishable, forage into a product that can be safely
stored and easily transported without danger of spoilage, while keeping losses
of dry matter and nutrients to a minimum. This involves reducing its moisture
content from 70 - 90% to 20 - 25% or less. Techniques for natural pasture, sown
pasture and crops specifically cultivated for conservation at three levels of
technology are considered: manual haymaking; simple mechanization with draught
animal power or small tractors; and fully mechanized systems. It is, of course,
possible to have some or all of the operations of haymaking done mechanically
under contract, provided that the fields are big enough to warrant it; this is
feasible where the climate at harvest time can be relied on. In areas of
uncertain climate, however, it is less suitable, since equipment must be on hand
for each operation as the weather and condition of the hay dictates. Further
notes are given in Chapters III to VI, where hay crops are discussed.
Problems in haymaking vary according to the crop, climate and prevailing weather at harvest:
The main discussion is on climates where drying is a problem, as these are the most difficult for haymaking. Fine-leaf grasses and legumes are traditional hay crops in most areas but, in the subtropics, hay is made from coarse cereals such as maize and sorghum, now mostly in small-scale farming situations, notably in India and Pakistan. On mechanized farms, nowadays, coarse cereals are usually ensiled.
Where hay is made from pasture, rather than arable crops, the fields may be both grazed and mown at different seasons of the year. If the main output of a field is hay, it will still be grazed when the weather is unsuitable, then left for the forage to reach the correct stage at the optimum season for haymaking; the aftermath may thereafter be grazed. With grazing fields, the immediate requirements of the stock has priority but, at the season of peak grass growth, forage availability outstrips the needs of the herd and the whole or part of fields (shut off by electric fences) may be used opportunistically for hay.
Hay may be made in several forms, according to the conditions, its intended use and the level of technology.
- Long hay, the traditional, age-old form of herbage, mown, turned and carted is the main subject of this book.
- Chopped hay is an option where conditions for drying are good and systems highly mechanized; it is less bulky and better for mechanical handling, but must be conditioned, windrowed and collected with a forage harvester.
- Baled hay. Originally baling was by hand (trusses or bottles), and then by stationary machines. It has been automated since the 1950s, with the introduction of the pick-up baler. Big bales which can be individually handled by a tractor-mounted front-end loader are now the main kind in large-scale farming; round bales are the simplest to make and most popular. Their shape sheds rain and resists water better than traditional bales.
- Hand-trussed hay is widespread in manual haymaking, often as a means of reducing shattering.
- Wafered and pelleted hay is dense and free-flowing, so it is easy to transport, handle and store. Field units are available, but expensive; they are used for high-quality legume hay in climates which allow rapid drying. Losses are lower than with baling.
- "Dried grass," i.e., herbage artificially dried at high temperatures, has been produced from time to time; the process allows conservation of a younger and higher quality material, but it is not currently economically attractive.
- Barn-dried hay. Equipment for fan-assisted drying (with or without additional heat) is now available, but is not widely used.
The drying process
Moisture-loss is rapid at first, especially from the leaves, as the stomata are open. As the herbage wilts, the stomata close and water has to find ways out through the waxy epidermis of the leaves and stems. The moisture inside the stems takes longer to get out. With the coarser forages, some mechanical conditioning at the time of mowing is necessary if the crop is to dry evenly and in a reasonable time. The rate of drying, of course, depends on the weather: sunshine, wind and the moisture content of the air are the main factors.
Drying should be done as quickly as possible to minimize losses. At mowing, the herbage will contain between 70 and 90% of moisture, and this will have to be reduced to between 12 and 20% before the hay can be stored safely. The safe moisture content will depend on a range of factors, including storage method; local climatic conditions; size of stacks or bales; where the hay is to be stored; and the nature of the crop. As a very rough guide, 25% moisture is recommended as a maximum for long loose hay; 20% for chopped hay and 5% for pelleted, cured hay.
The swath is the mown forage lying in the field; the windrow is either made by raking one or more swaths together or formed directly by a mower-conditioner or windrower. After drying in the swath, further drying in the bale, stack, barn or field may be needed. The harvesting method used should match the rate and total amount of drying that can be expected in a swath or windrow. The quality of hay can be roughly assessed in the field both visually and by handling, twisting a bunch if necessary. It should feel crisp and look bright. Bleached hay always indicates a badly weathered crop.
The drying process in the swath is reviewed by Jones and Harris (1979). The stomata close soon after the herbage is mown. The amount of water to be removed is "roughly equivalent to that transpired by the crop in one day under the conditions of May and June in the south of England." There are two types of limitation to water loss: (i) those which restrict movement of water from plant tissues to the air immediately surrounding the plant within the swath, and (ii) those which restrict the movement of water from the air within the swath to the ambient air. The most favourable conditions for drying are at the swath surface, where both radiation and air circulation are at a maximum. The requirements for drying are a supply of energy and a water vapour gradient decreasing from the evaporating surface to the ambient air; this varies throughout the swath. Within the swath, a microclimate develops which limits water loss. As drying progresses, the humidity gradient within the swath increases because density is reduced as water is lost, so more solar radiation can enter and air-flow is improved. Under British conditions, Jones and Harris (1979) recommend that if the weather is sunny the swath should be spread to get the full benefit of radiation; if conditions are dull but windy, then the swath should be set up for aeration. Again under British conditions, Clark and McDonald (1977) found that in July there was limited evaporation from the swath from dawn to 09:00, high evaporation from 09:00 to noon, a decrease from noon to 18:00 because of decreasing available energy and increasing swath resistance, and evaporation was almost zero after 18:00.
Haymaking methods vary depending on crop and circumstances, but the main operations are more or less the same in all cases:
To keep losses and spoilage to a minimum, operator skill and experience is essential in giving the attention to detail which is necessary throughout the haymaking process. Much depends on the judgement and experience of the operator. The main way of minimizing loss is to dry the herbage as rapidly and as evenly as possible, and handle it with care thereafter.
Causes of loss include those considered below.
- Fermentation, with losses beginning as soon as the crop is mown. Enzymatic oxidation of the sap and the activity of bacteria and moulds on the crop surface cause losses, with generation of heat. If the crop is not aerated sufficiently to dissipate the heat, serious damage can occur. Turning and tedding must therefore be prompt and adequate.
- Mechanical leaf loss occurs during tedding and field handling.
- Leaching losses occurs if rain falls on the crop during the curing process. Re-wetting of partially dried hay is much more serious than rain on newly-cut herbage, and can cause both leaching and increased mould damage. Should rain be imminent on a partially-dried crop, it should, if possible, be gathered into bigger windrows or cocks.
- Further mechanical loss occurs during collection, transport and baling. Their severity depends partly on the skill of the operator.
- Spoilage in the stack or bale is particularly dangerous, and can lead to the loss of the entire harvest, usually as a result of storing material which is at too high a moisture content in over-large units or poorly designed stacks which allow rain penetration or do not allow some ventilation. The ideal moisture content for stacking or baling depends on the crop and the site, and experience and field judgement must be the general guide. The farmer must judge by feel and make a decision in the light of the prevailing weather: when the herbage feels crisp in the hand and does not show moisture when twisted, it is probably at 25 - 30% moisture and ready to bale. Moisture meters are not generally available nor convenient to use in the field, and taking a representative sample is not easy. Fine-leaved, thin-stemmed herbage dries most quickly; large coarse grasses with thick stems and nodes (e.g., Sudan grass) can still have a lot of juice in the stems after the leaves are quite dry. In extreme cases, the fermentation may raise temperatures to levels where spontaneous combustion occurs. Poorly cured or mouldy hay, apart from losses, will lead to poor intake or refusal by stock, and may contain mycotoxins. Mouldy hay gives rise to the human disease known as "farmers' lung."
- Wastage during utilization includes losses from opened stacks and poor feeding techniques. It is dealt with in Chapter X.
Hay preservatives
Several proprietary preservatives are now available; their purpose is to allow hay to be stored at elevated moisture levels that in the absence of preservative would result in severe deterioration or moulding. Hay of 40 - 50% can be stored. Propionic acid is one of the substances used. Anhydrous ammonia or urea treatment, which was originally developed for improving the digestibility of straw, has given good results in hay by improving its stability under anaerobic conditions, as well as improving its nutritive value. The ammonia, in addition to excluding air, has a fungicidal effect, and also increases the crude protein content of the hay. This is discussed in Chapter IX, where the treatment of straws and stovers is described.
Timing of harvest and stage of growth
Two main factors determine the timing of haymaking: the expected weather of the season and the stage of maturity of the crop. Usually the season will be pre-determined by potential availability of herbage and the likelihood of suitable haymaking weather. Pasture, natural or sown, will be managed, by grazing or taking silage cuts as necessary, so that the herbage reaches a suitable stage for curing when good weather is expected. Where sown forage is to be cured, the crop will be chosen and its cultivation organized to match good haymaking weather. If a farm intends to make a lot of hay, consideration must be given to growing a range of species and cultivars to extend the season during which the various crops will be in peak condition for haymaking, and thus make best use of the available equipment and labour.
All steps in haymaking should aim at producing as high a quality of product as possible, but the stage of maturity of the crop is the major factor determining the quality of the final product. Herbage quality drops off rapidly with increasing maturity, especially after flowering, but very young, leafy grass is less easy to handle than more mature herbage, and its yield is less. A compromise between yield and quality has to be made, and, usually, cutting at early to mid-flowering will give a reasonable product. Where tripod drying or barn-drying facilities are available, a younger product can be dried. In "good" haymaking climates, younger material can be cured more successfully than in areas with moist climates, or where there is danger of tropical storms. Cereals for hay are cut at a more mature stage than are pasture grasses, often when the grains are fully formed. Hay from natural pasture is more influenced by the natural growth cycle than are sown crops, and harvesting seasons are often traditional. Many hay meadows rely on natural fertility rather than applied fertilizer, so there is often only one period in the year when they carry sufficient herbage for haymaking.
The time of year depends on the availability of suitable herbage and the weather pattern. The rest of the farming cycle and availability of labour and machinery of course also have a determining role. The aim is always to have both high-quality herbage and a high probability of suitable haymaking weather coincide. Where there is an overall scarcity of forage, farmers may make hay even when the quality of the crop is poor. For example, in the monsoonal tropics and subtropics, a lot of hay is made from very over-mature herbage because the weather during the season when the grass is at its best quality is unsuitable for drying. The product is poor, but even hay which is no better than straw is highly valued. Examples are given in the case studies on Afghanistan, India, Pakistan and the Sahel.
The time of day to start is equally weather dependent, but if the day dawns fair, it is best to mow as early as possible. If the crop is very wet due to previous rain or heavy dew, it may be advantageous to wait an hour or two while the upper part of the crop dries somewhat, since standing grass will dry more quickly than a cut swath. Mowing should not, however, be put off too long, especially under tropical conditions, where afternoon showers are usual. If cut early, the crop can often be turned and windrowed in a morning, before the afternoon rain. Where the scythe is used for mowing, it is everywhere agreed that it is best to start while there is still dew on the herbage, since this greatly facilitates mowing. For haymaking by sickle, however, Skerman and Riveros (FAO, 1989) recommend waiting until the dew has dried. Early mowing allows the other operations, especially turning, to start early and increases the chances of having drying well advanced during the first day.
Deciding whether or not to mow on any given morning may be a problem. In arid areas and climates with a fairly definite dry season (e.g., making oat hay in the North African late spring, or irrigated fodder in arid areas) there is little difficulty. In uncertain climates, however, it is necessary to assess whether there will be a spell of good weather sufficient to allow the making of hay safely, or at least to be able to get it into large windrows. Local weather forecasts, as well as experience, will help, as the time required to cure hay varies greatly with site and climate. In good tropical and subtropical conditions, it can be cut and cured the same day; under humid temperate conditions, several days of good weather are required. In the UK, hay is rarely made in under three days. Delay once the crop has reached a suitable stage of maturity will, of course, reduce the likelihood of producing high-quality hay. Mowing when there is a possibility that poor drying weather will hamper curing may lead to slow drying, long periods in the field, rain damage and possible mouldiness. The final decision is one which requires all the farmers' experience and skill, but in a case of indecision it is probably better to mow than to put off.
The number of cuts per year varies greatly. On natural pasture, only one cut from the spring or summer flush is usually possible (unless the herbage is greatly modified by fertilizer). Sown pasture and fodder may provide several cuts. For pasture, alternate grazing and mowing (for either hay or silage) is often used, according to the needs of the herd and the weather at the time when a surplus to conserve is available. Hay can only be made when forage is available at the right stage and suitable drying weather is available! Irrigated crops in semi-arid areas have good haymaking conditions and cutting should be organized to maximize production while maintaining quality through frequent cuts. This is especially important for the major irrigated forage, lucerne, and details are given in Chapters III to VI. In warm, irrigated areas, cuts may be almost monthly.
Haymaking requires rapid action to take advantage of such good weather as is available, to make the best use of the equipment, labour and power available, and to synchronize and complete the multiple tasks involved. The amount cut should match the capacity for conditioning, tedding and baling, so that each part of the field is dealt with as it reaches the required moisture content.
General principles
All activities in haymaking must be done on time, from mowing, through turning, to windrowing and baling or stacking, otherwise the crop will spoil. At no point until it is won can mown hay be left. The amount mown daily must therefore correspond to the labour and machinery available for all the other activities that must follow. Mowing should be so organized as to minimize turning and "empty" time for the mower, and to facilitate subsequent operations. Whatever machine is used for tedding or windrowing, it is best to follow the mower round the field in the same direction when the swaths are first moved. If conditioning is done, it should be at, or immediately after, mowing, as should be the first turning to improve aeration and speed up drying.
Under good conditions, the made hay can be carted from the windrow after one or more turnings. The time involved varies greatly according to climate, weather and crop. In dry, warm subtropical conditions, hay can be trussed, baled or carted on the day of its cutting, and indeed may have to be in order to avoid undue leaf-loss through shattering.
Agronomic details of crop installation and management are dealt with at length in Chapters III and IV, but it is worth repeating that careful land levelling, at sowing and where necessary between mowings, is essential. Where frosts occur, heavy rolling in spring of fields with stones and pebbles on the surface is very worthwhile for protecting mowers. Heavy applications of nitrogenous fertilizers are limited by increasing density of sward, which hinders drying and can cause lodging, with subsequent harvesting difficulties and losses.
Damage by wheel traffic can lead to severe reductions in stand production and life, either through soil compaction or, especially in lucerne, by damaging crowns and re-growth when field operations are delayed. The lightest equipment compatible with the task should be used; mown herbage should be removed as soon as its condition allows and unnecessary passage on the field avoided. Great longevity of lucerne stands is claimed in some small-scale farming areas (Afghanistan, northern Pakistan) where all operations are manual. Could this in part be due to absence of damage by wheeled implements?
Mowing
Until the middle of the nineteenth century, all hay was hand mown. There are two basic hand tools: the sickle and the scythe.
Sickles are designed for cutting cereals, but are poorly adapted to mowing hay, and very slow and laborious in comparison to the scythe. They are, nevertheless, widely used, especially in India and Pakistan, often in a blunt, saw-edged version. Where farms are very small and haymaking a secondary task, equipment is kept to a minimum.
The scythe is the traditional grass-cutting tool of northern Asia and Europe. It can mow at about five times the speed of the sickle. It requires a sward which is reasonably free from obstacles, must be kept very sharp by regular whetting throughout the day, and requires some skill to use. A scythe cuts wheat faster than a sickle, but it does not leave bunches ready to tie. Where the preference in cereal harvesting is for the sickle, small-scale farmers seem loath to acquire additional cutting tools for the minor hay crop.
Table 1. Time taken for haymaking operations in Cameroun
In Africa, the machete (panga) is the all-purpose cutting tool and may be used for mowing. Data from Cameroun (Table 1) indicates that the scythe was only twice as fast as the panga for mowing but that may indicate greater familiarity with the local tool. The Argentine Chaco case study also mentions mowing with a machete.
Sickles come in a wide range of forms, and two types of blade edge: serrated or smooth. The blade may be semicircular, straight or slightly curved; it is usually inserted into a wooden handle by a tang; some have the blade attached to a metal shaft with a wooden handle. The section on fodder conservation in India mentions an unusual yak-horn sickle used in Ladakh. Cutting cereals with a sickle is very slow, but it allows careful reaping and avoids shattering of the ear; this, and its low cost, accounts for its continuing popularity with small-scale farmers. For mowing grass in substantial quantities, the sickle is slow and tiring, so it does not encourage any serious effort to cut forage and make hay in regions where it is the only available harvesting tool. It is a cheap, simple tool and is still very widely used all over the world. Sickle-cut hay is usually handled in bundles from the time of cutting, and is often carried to the homestead for final drying. The individual amounts are usually small, but, in aggregate, a great deal of hay is made this way, especially from irrigated lucerne in western and central Asia and from natural herbage in the monsoon zone. With a tool which is so clumsy, and often blunt, the herbage is usually pulled and cut at ground level; this damages some crops, especially lucerne, and every effort should be made to encourage cutting above the level of the young shoots which provide the next crop. Haymaking is very widespread in Afghanistan and the traditional sickle, used for clover and lucerne, is long-shanked and smooth-edged, often with a long handle. It is kept sharp and wielded one-handed with a scything motion, and works better and faster on lush legumes than would a grain sickle.
The scythe is essentially a grass-mowing implement, worked with two hands. It consists of a blade joined to a handle (the "snath" or "snead") by a ring connector. Two quite different types of blades are used: ground blades (sharpened on a grindstone) and hammered blades (sharpened with a hammer and small anvil). Both are finished off with a whet-stone, which is also used to keep the blade sharp in the field. Ground blades, the older type, are used in northern Europe and North America, whereas the hammered type, developed in Austria, are used in central and southern Europe, and have spread to Latin America. Whetting is the sharpening of the blade, in the field, by special stones (some require water if the herbage is dry) which are stroked over both sides of the blade, starting from the heel.
The blade, of mild steel, has a reinforced back, the end of which forms the tang for connection to the snead. Its length for mowing cereals and herbage is 75 - 100 cm (shorter blades are used for brush-cutting); longer blades require more skill in operation and a stone-free field surface. The width of the blade at the heel is 10 cm or less for mowing, but may be wider for dealing with thick-stemmed material. Sneads are traditionally of wood, although light metal tubes are now also used. The handle of the traditional type is long and has a grip in its middle for the right hand; some have a second grip at the top; an improved type used in Scotland has a Y-shaped snead with two grips.
Sneads vary considerably in design, but are designed to allow the operator to mow with outstretched arms and both hands on more or less the same horizontal plane so that the implement can be swung through a wide semicircle with the blade always parallel to the ground and without undue strain. The length of the snead and the position of the grip(s) should be determined by the height of the user. The blade is attached to the snead by a ring-connector which is fixed by a screw or wedge; this makes it possible to regulate the angle between the blade and the snead. The vertical alignment of the blade can be regulated, by a blacksmith, through modifying the angle of the tang to the blade-back.
Grass, especially thin stands of natural hay, is much easier to mow with a scythe in the morning when the dew is still on it. Scythes are frequently recommended in new areas where hay is being popularized, often with little success; the reason may be that the art of scything, in the western world, is largely forgotten and few technicians now have the necessary expertise to effectively demonstrate this arduous and skilled task, including scythe maintenance. Mowing with a scythe is a skilled job, and very different from cutting with a sickle. Forage crops are mown with wide cuts, advancing in a straight line and cutting away from the standing crop. A scythe cuts about 2½ times the length of the blade, so a 75 cm one will mow a swath 175 cm wide if the crop is not too heavy, with the width reduced in a denser crop. On good, level, stone-free ground, about 500 m2 can be mown per hour.
Turning and tedding
Like mowing, windrowing and turning was done by hand until relatively recently Various home- or locally-made wooden forks and rakes were used, and are still common. Turning by hand, without tools, is not uncommon, but very laborious. Metal-tined forks came in latterly. The fork is used for all manipulation of hay during loading and stacking. Herbage may be taken to the homestead for final curing, in a place where it is out of the way of livestock. There are several reasons for homestead drying, including the availability of suitable drying areas, convenience for turning and handling small quantities without having to travel to the field (which may be at some distance in the case of natural herbage in mountainous areas), and also the possibility of theft from the field. Examples of this fairly widespread system are given in the case studies on Afghanistan, Liaoning and Pakistan. Small quantities are often stored on rooftops, in trees and around farm buildings in traditional systems, often to keep it out of the reach of foraging livestock.
Where drying is slow and weather uncertain, the hay can be put into cocks by hand for several days; it may also be cocked when rain is imminent and then re-spread following the rain. Intermediate stacking in large cocks with a central wooden tripod for ventilation was once common in northern Britain for completing field drying before final stacking. Cocks and large windrows are also used in hot, dry areas to avoid shattering and sun bleaching.
Baling started as trussing - hand rolling into bundles - a practice still common in some areas where natural grass is traditionally mown. Small trusses are widely used for legume hay in semi-arid areas of Asia as a means of reducing leaf-loss. In the case studies, trussing is reported from Argentina as well as most countries in semi-arid Asia. Stationary hand presses were developed where hay and straw had to be transported over long distances; they are still used in some areas, as reported in the case study on the Argentine Chaco.
Transport was the first operation in haymaking to be mechanized - long before mowing - and animal-drawn carts have long been used. In order to better carry the bulky loads, frames are added at haymaking in order to increase the carts' area. Pack-saddles are also used, as well as back-frames and ropes for porters, mainly on land too steep for or inaccessible to wheeled vehicles. When transported by cart, the hay is usually loaded by pitchfork and carefully built on the wagon: the corners should be laid down first, then the sides, and finally the centre, layer by layer, taking care to see that each forkful locks the previous one. Carting high, bulky loads on sloping land is not easy; if the land is at all steep it may be necessary to work with the slope, and this should be taken into account when windrowing the crop.
Mowing
Horse-drawn reciprocating-blade mowers were introduced in the early nineteenth century in the USA and soon became the main grass-cutting machine of large-scale agriculture. The mower has a main frame, with a seat for the operator, mounted on two wheels, from which power is transmitted through a live axle and differential gears to the cutting mechanism. The gears of the differential drive run in an oil-bath. The cutting mechanism is connected to the main frame by a double-jointed drag bar which allows adjustment of the cutter bar by levers. A crankshaft and connecting rod (pitman) transform rotary motion into reciprocation. The cutter bar is usually 1.25 m or more long, carrying ledger plates with "fingers" which form half the scissors. The cutting action is completed by the reciprocating knife bar with triangular blades. Knife sections are easily removable by punching out two rivets and inserting new pieces. There is a prolonged swath-board at the end of the bar to lay the mown herbage away from the standing crop.
These mowers are of relatively simple construction and can be maintained and repaired by elementary workshops, but require clean fields and the blades must be sharpened regularly. It is essential that the ledger plates of all fingers be in alignment so that the knife sections slide over them smoothly. The cutter bar is in proper alignment when the crank-pin, the knife head and the outer end of the knife are all in line. Cutter bars and knives are exchangeable. This type of mower has a power requirement of 1.5 kW per metre of cut, and forward speeds of 3 to 8 km/hr are suitable. It is the only type of mower which can be drawn by livestock.
The mower is usually drawn by two animals and enough will be mown at any one time to suit the rest of the handling equipment and labour. The swath should be turned by hand, or star-wheel rake if available, soon after mowing. Further handling will either be manual or by simple equipment. A dump-rake is very useful for forming windrows and gathering the hay for carting. Carting and stacking is as for manual haymaking (see above).
Swath manipulation
Turning and tedding is often by hand, although horse-drawn dump-rakes, sweeps and tedding machines were developed in parallel with mowers, and later adapted to mechanical traction. The dump rake (Figure 9) is the commonest and most useful implement; it consists of a large number of long, slightly curved teeth on a bar parallel to its axle, with a pawl and ratchet mechanism for tripping the rake, worked by a foot pedal by the operator sitting on a seat and guiding the horse. It is used for dragging hay into windrows and for cleaning hay and corn stubble.
Cocks, tripods and rack-drying
Where there is danger of re-wetting, which is very damaging, there is an intermediate stage where the partially-dried herbage is put into small heaps - "cocks" - to dry further with less danger of rain affecting the whole mass. Under sub-optimal conditions, the cocks may be built on wooden tripods to improve ventilation, or the hay may be put on drying racks - all labour-costly operations. They are also useful in hot dry areas where the best quality hay is made by putting it up in cocks, which reduces both shattering and weathering and produces a green, leafy hay high in carotene. Racks and tripods, however, require a cheap supply of poles, not always readily found. Fully mechanized systems attain a similar effect through careful swath handling and windrowing. IEMVT (1992) describe and recommend several drying structures for small-scale farming use. These include a "Canadian tent," which is built from two A-frames with a ridge pole and one or more poles on the sides; tripods; and a "Scandinavian fence" of posts and wire.
Collection, loading and transport
Horse-drawn sweeps were developed to push several sections of windrow together for ease of collection, and some have a tumbling action so that they discharge easily. Cranes were also used for loading hay onto wagons or from wagon to stack, and in the field they were especially useful where intermediate on-field stacking was used. Such equipment was used on large farms, and these are now highly mechanized. In small-scale farming systems, loading is by fork and hay is transported on carts, which may be temporarily modified by the addition of frames to increase their base area to allow transport of a greater load of bulky material.
Small tractors are becoming increasingly common in developing countries, and often their owners do some contract work as well as tending their own farms. Old and simple techniques of mowing and sward handling can be introduced with a minimum of equipment and investment, but can speed up and improve haymaking a great deal. A mower, dump rake and some frames to expand the loading area of existing trailers will go a long way toward mechanizing the hay harvest. In the case study on Altai, for example, a centrally-run machine pool with heavy equipment proved less attractive than simple mechanization run by farmer-contractors with the kind of equipment mentioned above.
Mowing
When tractors came into use, reciprocating mowers were adapted to suit them; the first, trailed models worked from the ground wheels, and then mounted models evolved, driven from the tractor's power take-off (PTO). Of the PTO-driven models, mid mounted bars are by far the simplest to work with since the bar and control are in front of the driver and the drawbar is free for other equipment. The close-coupled arrangement allows square cornering. The reciprocating mower's power requirement is about 1.5 kW per metre of cut, and a forward speed of 3 to 8 km/hr gives a rate of 0.2 - 0.6 ha/hr for a 1.5 m cut. Over a season, the work will be about 50% of that "spot" rate.
Swath manipulation
Dump-rakes have been adapted to be drawn by tractors. Finger wheel machines are simple and light implements; they are gear-less. A number of independently mounted large diameter wheels with spring teeth arranged radially are set in an oblique frame. The wheels, which gain their motion from contact with the ground, are free to float and overlap each other. When the wheels are on a single bar, they act as a side-delivery windrower. On double bar machines, the wheels can be arranged in two banks, one before the other for swath turning.
Stationary ram-balers (powered by tractor or engine) were developed for use where hay or straw had to be transported. These have been replaced on larger farms by pick-up balers, but are still used in conjunction with animal drawn and other simple methods of haymaking. The case study on Pakistan mentions that straw is baled for transport to the large cities.
Many levels of equipment and sophistication are now available. With a light tractor, such as those commonly found in small-scale farming areas, and some simple raking or turning equipment, the system will be little different, although quicker, from haymaking by draught animal power. Where fields are large and heavy equipment available, specialized equipment will be used and the hay will usually be baled in the field and stored as bales. The mechanization of haymaking, baling and handling is now highly developed.
Mowing
The mower should be able to cut the forage to be handled in a day. A speed of 15 km/hr with a narrow cut of 1.8 m will cut 1.5 to 2 ha/hr. For high output, 2 to 3 m-wide cuts are possible, but the swath should be gathered to 1.6 m to allow passage between tractor wheels and match subsequent equipment; the drying rate is reduced by this thicker row. The mower should be capable of operating continuously, without blockage even in dense and laid crops. Less than 25% of the time should be taken up by turning, travel between fields, delays and adjustments. When there are stones, etc., adjust the mower to cut above them, say 4 cm above the soil. The traditional cutter bar mower was described above. The "finger-less double-knife" mower is less susceptible to blocking, but needs special sharpening equipment. They can work at 10 to 14 km/hr and mow 6 to 10 ha between sharpenings. Self-propelled mower-windrowers, with the cutter bar at the front, are now also available.
Disc mowers
Disc mowers, which have a cutter-bar fitted with two to six rapidly rotating discs, are a more modern tool and stand up much better to situations of poor field levelling and coarse herbage (Figure 11). Their action has a more bruising effect on the herbage than does the reciprocating knife, so the hay dries more quickly. With a power requirement of 7 to 15 kW per metre of cut (this power requirement can double when the machine is worn or cutters blunt) and a forward speed of 10 to 15 km/hr, a tractor of 35 hp (26 kW) is required for a four-disc model. Disc mowers are unsuitable for animal draught. Disc mowers are unlikely to block in laid or heavy crops. Knife maintenance is simple, and a set of knives will last 40 ha under reasonable conditions. Attention must be given to knife height as well as to the fore-and-aft setting of the cutter unit. Disc mowers can operate at up to 16 km/hr, but 10 to 13 km/hr is more practical. Their working rate is 0.5 to 1.5 ha/hr per metre of cut. Double-drum mowers are now widespread in western Europe.
Conditioners
The aim of conditioning is to reduce the period when the crop is at risk; it should not only increase the drying rate but should also encourage even drying. Conditioning is, of course, only really effective when conditions are suited to removing the moisture thus made accessible. Machine conditioning usually leads to some nutrient loss through breakage. Conditioning is most effective when done at cutting or immediately afterwards; it is usually achieved by either crushing or crimping. Crushing is done by passing the crop between plain or fluted rollers; crimping may crush, but also bends the herbage at 5 to 10 cm intervals and may bruise leaves. Modern equipment includes mower-conditioners that partially crush the sward, as well as cutting it, thus accelerating drying. Early mower-conditioners were designed for lucerne in the USA and comprised a mower followed by crushing or crimping rollers. They work well in a medium crop, but not in a heavy one under European conditions. In Europe, drum or disc mowers, 1.5 to 3 m wide, followed by intermeshing rollers, are used but, increasingly, overshot tedders which abrade the herbage against a concave as it passes are commonly used in conjunction with drum mowers.
Swath handling
Tedding immediately after mowing boosts the drying rate. Conditioning or crushing should be done within twenty minutes of mowing. Timing of swath handling is critical and, at a time of peak demand for traction and labour, it is desirable to have a machine with a high work rate and a low power demand. It should have a wide working width and follow the land surface well to ensure that the maximum of the crop is properly treated. Most modern machines use configurations of tines moving in a near-horizontal plane, and some have drums to deliver the crop to one side. If a large windrow is required, the machine can be driven in alternate directions to combine two rows together. Overshot tedders are increasingly used. They have a series of flails on a horizontal axis, which pick up and aerate the swath. Some machines combine several functions and can ted, spread or windrow, depending on the position of the crop-directing cage. Machines for pick-up in line with the tractor, such as balers, must have a swath of uniform cross section.
In cool, temperate conditions the swath has to be raised for aeration. Under hot, dry conditions, it may be beneficial to spread it over the greatest possible area to benefit from the sun. In most temperate situations it is necessary, however, to tease out, mix and turn the swath as drying proceeds. Unless the weather is warm and sunny, the swath should be set up to catch any air movement across the field. Both crimpers and conditioners are designed to set up the swath and assist air movement. If rain falls on a windrow prepared for baling, the windrow should be split into its original parts as quickly as possible, or drying will be very slow. In very hot, arid conditions, too-rapid drying of the leaves leads to shattering and bleaching, but windrowing will palliate this. Drying can be speeded up by collecting the half-dried hay into narrow, compact rows overnight, and spreading it out over all the ground once the soil between the rows has dried in the morning. The swath must always be collected into windrows for carting or baling. Speed of baling depends greatly on the type of windrow presented to the pick-up reel.
Bales and balers
Pick-up baling is now the norm in most mechanized haymaking. Two basic types of bale are made: the standard rectangular bale, which can be handled manually, and the, usually cylindrical, "big bale" of about 500 kg, which is handled using the tractor's front-end loader. A "standard" bale is nominally 36 cm ´ 46 cm ´ 90 cm, and weighs 15 to 25 kg, according to the density of the bale and the moisture content of the hay. It is suitable for manhandling and provides a hay ration for four to ten dairy cows. Such bales are useful when small quantities of hay are needed some distance from the store or in buildings not adapted for mechanized handling.
There are two types of standard balers. Most are of the slicing ram type, in which the reciprocating ram that compresses the forage in the bale chamber is fitted with a knife to slice through the herbage at the end of each stroke. If the knife is properly maintained and set, then slices which can be separated will be formed. Bale density can be adjusted from 80 kg/m3 to 220 kg/m3 by adjustment of spring-loaded plates. On most balers, the length of the bale can be adjusted over a range of between 1½ and 2 times the bale width. The swinging ram, or press baler, has a folding action in which the successive charges are not cut. Under similar crop and conditions, it produces a less tidy bale, usually of a lower density than does the slicing-ram baler. Such bales have an advantage, however, in that air can penetrate them more readily and give better ventilation, which is useful in handling a crop with high moisture content.
The pick-up of a baler should be wide enough to deal with a heavy crop; preferably able to take a swath of over 1.5 m width. A combination of narrowly spaced pick-up tines, a freely-floating pick-up wheel and a spring-loaded guide is most likely to pick up cleanly. The flow of the crop from pick-up to bale chamber must be free of obstructions. Easy adjustment of packers is necessary if well-shaped bales are to be produced. If the feed is uneven, the bale will curve away from the denser side and binding strings may become detached.
Knotters should be able to handle a range of twines. Full out-of-season maintenance of the baler, and its knotter, is very necessary.
The machine must be adjusted according to the type and moisture content of the hay, which will vary according to the time of day and position in the field, so continual operator attention is essential. Moist hay gives heavy bales, which may burst the strings if too dense and/or too large. Light, stemmy hay gives light bales with loose strings. Bales should be examined for moisture content and shape as they leave the chamber. In the UK, hay is baled at 20 to 35% moisture, with the higher levels intended for subsequent barn drying. High-moisture-content bales should be made shorter than dry ones. The output of balers varies between 3.5 and 10 t/hr, but is usually around 6 to 7.5 t/hr or 1 ha/hr. Mechanization of loading and handling is by trailing wagon, or systems which, for weather protection in the field, group bales into pyramids of 3 to 15.
The activities involved in handling standard bales are grouping, loading onto transport, unloading, and loading into the store. If carting directly from the baler to the store is possible, then that is ideal, but this is not often the case. Small stacks of bales are often made in the field for a holding period or under temporary cover; the hay is partially protected from the weather while the heat from oxidation and some moisture is dissipated. Field stacking separates the handling into stages in the event of labour scarcity. The shape and size of the heaps should be decided on as an integral part of the handling system, and must not reduce baler output. Stack size is related to field size and topography, as well as to building size and layout. It is necessary to estimate how much hay will have to be handled in unit time to avoid spoilage between baling and storage. Single bales can be picked up from rows and loaded directly on to trailers (180 bales per person per hour). Hydraulically operated swinging-arm loaders can tumble-load about 400 bales/hr. A team of three with such methods can haul and store up to 200 bales/hr, or 70 bales per person per hour, which is double the hand-loading rate. Extended chutes and throwers attached to the rear of the bale-chamber allow rapid clearing of the field, but require a lot of trailers. Stacking the bales on a trailer is hard work, and if the labour does not keep up, then baling is delayed. Turning time is greatly increased with such a long train of equipment.
Single bales, as dropped by the baler, are very susceptible to damage from heavy rainfall, and also interfere with the re-growth of the crop if left more than a few days. It is common to collect bales into groups, which are often made into small intermediate stacks in lines or on headlands. If the tops of the stacks are protected - such as by plastic sheeting, tarpaulin (Figure 12) or thatching - they can be kept safely in the field for some time. Plastic covers should be removed periodically to allow condensation to dissipate. Collection after the baler using manned sledges usually slows baler operation. Automated systems, such as random collectors and fully automatic bale collectors, which collect bales and form groups which can be picked up by the loader without further handling, eliminate the need to form them into units by hand. The simplest arrange bales into flat units of eight to ten.
Big bales
There are two main types of large round balers. Fixed-chamber balers have a chamber of a fixed diameter; in the initial stages hay is packed at random, then a rolling action starts when hay comes into contact with the bale-forming mechanism (rollers or chains and slats). This completes the bale with a spiral of compressed, roughly aligned crop. The outer layers of these bales are denser than the core, and bale size is predetermined by the size of the chamber.
In variable-chamber balers, the bale-forming mechanism expands with the bale, which is thus subjected to continuous rolling. Bale size can be determined by tying at almost any stage of the process.
Big balers come in sizes ranging from 0.9 m diameter by 1.2 m length, to 1.8 m diameter and 1.5 m length. Bale density is commonly between 110 and 120 kg/m3.
Big balers are relatively simple in operation and construction, but the shape and stability of the bales depends greatly on the shape of the windrow picked up and the skill of the operator. The crop to be baled should be drier than for standard baling, and preferably less than 18% moisture. Bales are wrapped with thin twine and then ejected, and the tying can take 30 - 40% of baling time. Their working rate is 6 - 10 t/hr, depending on the crop and bale size. Bales are left in the field to aerate before they are stored, as artificial drying is not easy. Big bales are greatly used as a means of storing straw, especially for later ammonia treatment. Big bales, which are handled at all times using the front-end loader, should be removed from the field as quickly as possible after baling to avoid damage to the crop, and placed, singly, on their sides in a suitable storage area with a space between adjacent bales. When storing bales, keep in mind the state of the site throughout the year, and not just at the time of harvest.
Hay can be kept for long periods if properly made and correctly stored; in contrast, it can deteriorate rapidly and even be lost by careless storage. The aim in storing hay is to keep it dry and to protect it from wastage due to rots, pests, stray livestock, fire or wind.
Storage areas, whether stack-yards or for bales, should have a dry foundation throughout the year, not only at the season of storage. They should be accessible all year round to the type of transport used, and protected from stray livestock and any fire risk. Where possible, it is better to store close to the point of use rather than in the field. Barn storage is ideal, of course, but is not always feasible.
Stacking
Stacks of loose material are the traditional method of storing large quantities of hay and, apart from barn storage, were the principal system on large as well as small farms until the introduction of the pick-up baler revolutionized commercial haymaking.
Once the hay has been field-dried to a suitable stage, it is carted to the stack-yard and built into stacks. The hay must be carefully built on to carts in the field and taken off in the same order as it was loaded. Under no circumstances should it be tipped off the cart if it has to be hand-forked to the stack, as random hay is very difficult to pull from the heap. Stacking is a skilled job and the quality and safety of the harvest depends heavily on the skill of the builder, especially in regions of moderate to high rainfall. Stacks may be cylindrical or rectangular in section, depending on the quantities involved and the condition of the hay. Often they are built on a base of loose stone for aeration, and in humid-temperate zones a central wooden tripod can be put at the centre of cylindrical stacks for aeration. Skerman and Riveros (FAO, 1989) recommend stacking on a base of hardwood poles, but this will depend on availability and price. When building the stack, the centre must be tightly packed, otherwise the stack will sag as it settles and rain may penetrate. The sides should slope outwards slightly to the eaves and the head thereafter rise gently to a point or ridge. Ropes or nets are used to protect the stacks against wind. Thatching with coarse grass or straw is common in areas where rain is expected during storage. This should not be done immediately, because it is necessary to allow dissipation of heat and moisture following stacking.
The yard must be kept tidy throughout stacking and storage, and vermin such as rats should be eliminated if possible. Apart from the damage they may do, rodents in stacks in warm areas attract snakes, which can be distracting to the labour when the hay has to be taken out for livestock feeding. Termites are another possible cause of damage. In areas subject to high winds, windbreaks, such as earth walls, have to be constructed, else it is not possible to store hay in the open. In severe cases, the stack may be no higher than the windbreak.
Mud-plastered stacks are traditional in areas where straw is chopped at the time of threshing, and are described in the case studies. This system does not appear to be used for hay. Storage of hay and straw in the forks of trees is widespread, especially for straw, in order to keep it out of reach of wandering livestock.
House-top storage is very common on smallholdings in semi-arid areas where flat-roofed houses are traditional; the house roof is often used as a drying area for other crops, as well as hay. In areas of negligible precipitation, this is an excellent storage method, but where there is rain the hay will be damaged by weathering. One reason for using the roof top is, of course, to keep the hay out of the reach of livestock around the homestead; another reason may be added insulation. This system has an inherent fire risk.
In parts of India and Nepal, terai wooden shelters are commonly constructed near the homestead for milch stock, usually buffaloes. Terai are flat-roofed and serve as storage platforms for straw and hay, as well as protecting the stock from the sun. Some have a protruding central pole to better retain the stored hay or straw.
Fire Risks
Hay is easily set on fire, as are dry crop residues, so care must be taken in siting stack-yards and storage so as to minimize the risks. Stored hay may be accidentally ignited by household fires, by smokers' carelessness, by sparks from bush fires, and so on. Care in siting, cleanliness - including tidying up of loose hay which could carry fire - and avoidance of smoking or other sources of fire near or in the stack-yard will help prevent accidents. Where dry fodder is stored on or close to houses, extra care is needed. Spontaneous combustion can occur when hay is stored at too high a moisture content.
Arson is another risk: an interesting solution to arson of haystacks, in an area where such a means of settling scores is not uncommon, is given in the case study in eastern Turkey, where the authorities insisted on communal stack-yards - if one burnt all would burn!
Bale storage
Advances in mechanization have concentrated more on clearing the field than handling in the store. Elevators move bales from the trailer to the stack, but the speed of operation does not match field handling systems. A team of three is required to feed an elevator and stack the bales, and such a team will handle about 420 to 500 bales per hour. Where the building layout is suitable, front-end loaders are used for stacking in the store.
Fractionation of legume hay
Traditional ways of separating the leaves and stems of leguminous hays for different uses have been noted in China. The final drying of the hay is usually done in the house compounds, and once really dry, it is beaten lightly, the leaves fall and are separated from the stems. The leaves are high-quality feed and are often reserved for monogastric livestock. When the hay is lucerne, the stems will be used for ruminants (see the Liaoning case study (Case Study 5 in Chapter XI)). In very fuel-deficient areas of the Loess Plateau, both sweet clover (Melilotus spp.) and North China milk-vetch (Astragalus adsurgens) are treated in this way, and the coarse stems used as fuel. This is only done where there is plentiful family labour. A similar technique sometimes is used to collect the leaves of trees and shrubs while still green: the loppings are heaped in a well-ventilated and sunny place and turned, where the leaves fall, are collected and further dried for storage. The remaining branches are used as domestic fuel. Caragana spp. are sometimes treated thus on the Loess Plateau, as are Alhagi spp. in northern Afghanistan. Ziziphus spp. are coppiced and dried in parts of Rajasthan.
Source: http://www.fao.org/docrep/005/X7660E/x7660e06.htm
Problems in haymaking vary according to the crop, climate and prevailing weather at harvest:
- Under sub-humid and humid temperate conditions, the main problems are related to slowness of drying, so, to avoid loss by spoilage, the aim is to dry the crop as quickly as conditions will allow.
- Under hot, dry conditions, in contrast, the problems are more likely to be either shattering of the finer parts of the plant, through too rapid drying, or bleaching, with consequent loss of carotene and vitamins.
The main discussion is on climates where drying is a problem, as these are the most difficult for haymaking. Fine-leaf grasses and legumes are traditional hay crops in most areas but, in the subtropics, hay is made from coarse cereals such as maize and sorghum, now mostly in small-scale farming situations, notably in India and Pakistan. On mechanized farms, nowadays, coarse cereals are usually ensiled.
Where hay is made from pasture, rather than arable crops, the fields may be both grazed and mown at different seasons of the year. If the main output of a field is hay, it will still be grazed when the weather is unsuitable, then left for the forage to reach the correct stage at the optimum season for haymaking; the aftermath may thereafter be grazed. With grazing fields, the immediate requirements of the stock has priority but, at the season of peak grass growth, forage availability outstrips the needs of the herd and the whole or part of fields (shut off by electric fences) may be used opportunistically for hay.
Types of hay
Hay may be made in several forms, according to the conditions, its intended use and the level of technology.
- Long hay, the traditional, age-old form of herbage, mown, turned and carted is the main subject of this book.
- Chopped hay is an option where conditions for drying are good and systems highly mechanized; it is less bulky and better for mechanical handling, but must be conditioned, windrowed and collected with a forage harvester.
- Baled hay. Originally baling was by hand (trusses or bottles), and then by stationary machines. It has been automated since the 1950s, with the introduction of the pick-up baler. Big bales which can be individually handled by a tractor-mounted front-end loader are now the main kind in large-scale farming; round bales are the simplest to make and most popular. Their shape sheds rain and resists water better than traditional bales.
- Hand-trussed hay is widespread in manual haymaking, often as a means of reducing shattering.
- Wafered and pelleted hay is dense and free-flowing, so it is easy to transport, handle and store. Field units are available, but expensive; they are used for high-quality legume hay in climates which allow rapid drying. Losses are lower than with baling.
- "Dried grass," i.e., herbage artificially dried at high temperatures, has been produced from time to time; the process allows conservation of a younger and higher quality material, but it is not currently economically attractive.
- Barn-dried hay. Equipment for fan-assisted drying (with or without additional heat) is now available, but is not widely used.
Principles
The drying process
Moisture-loss is rapid at first, especially from the leaves, as the stomata are open. As the herbage wilts, the stomata close and water has to find ways out through the waxy epidermis of the leaves and stems. The moisture inside the stems takes longer to get out. With the coarser forages, some mechanical conditioning at the time of mowing is necessary if the crop is to dry evenly and in a reasonable time. The rate of drying, of course, depends on the weather: sunshine, wind and the moisture content of the air are the main factors.
Drying should be done as quickly as possible to minimize losses. At mowing, the herbage will contain between 70 and 90% of moisture, and this will have to be reduced to between 12 and 20% before the hay can be stored safely. The safe moisture content will depend on a range of factors, including storage method; local climatic conditions; size of stacks or bales; where the hay is to be stored; and the nature of the crop. As a very rough guide, 25% moisture is recommended as a maximum for long loose hay; 20% for chopped hay and 5% for pelleted, cured hay.
The swath is the mown forage lying in the field; the windrow is either made by raking one or more swaths together or formed directly by a mower-conditioner or windrower. After drying in the swath, further drying in the bale, stack, barn or field may be needed. The harvesting method used should match the rate and total amount of drying that can be expected in a swath or windrow. The quality of hay can be roughly assessed in the field both visually and by handling, twisting a bunch if necessary. It should feel crisp and look bright. Bleached hay always indicates a badly weathered crop.
The drying process in the swath is reviewed by Jones and Harris (1979). The stomata close soon after the herbage is mown. The amount of water to be removed is "roughly equivalent to that transpired by the crop in one day under the conditions of May and June in the south of England." There are two types of limitation to water loss: (i) those which restrict movement of water from plant tissues to the air immediately surrounding the plant within the swath, and (ii) those which restrict the movement of water from the air within the swath to the ambient air. The most favourable conditions for drying are at the swath surface, where both radiation and air circulation are at a maximum. The requirements for drying are a supply of energy and a water vapour gradient decreasing from the evaporating surface to the ambient air; this varies throughout the swath. Within the swath, a microclimate develops which limits water loss. As drying progresses, the humidity gradient within the swath increases because density is reduced as water is lost, so more solar radiation can enter and air-flow is improved. Under British conditions, Jones and Harris (1979) recommend that if the weather is sunny the swath should be spread to get the full benefit of radiation; if conditions are dull but windy, then the swath should be set up for aeration. Again under British conditions, Clark and McDonald (1977) found that in July there was limited evaporation from the swath from dawn to 09:00, high evaporation from 09:00 to noon, a decrease from noon to 18:00 because of decreasing available energy and increasing swath resistance, and evaporation was almost zero after 18:00.
The main operations in haymaking
Haymaking methods vary depending on crop and circumstances, but the main operations are more or less the same in all cases:
- mowing, which may be combined with conditioning;
- artificial conditioning for rapid drying. (an innovation, and only sometimes carried out);
- turning and tedding to allow even drying of the swath, help dissipate heat and reduce the danger of mould development and fermentation;
- windrowing, i.e., putting the cut herbage into rows for further handling and collection, and sometimes also for protection at night. In hot arid conditions, windrowing protects the crop against shattering and bleaching;
- trussing or putting into cocks (small heaps) are intermediate stages of drying used in some manual systems; and
- carting and storage, with or without baling. In traditional systems the cured long hay is carted and stored in stacks or barns. Baling before storage is much more common in modern, mechanized systems.
Losses in haymaking
To keep losses and spoilage to a minimum, operator skill and experience is essential in giving the attention to detail which is necessary throughout the haymaking process. Much depends on the judgement and experience of the operator. The main way of minimizing loss is to dry the herbage as rapidly and as evenly as possible, and handle it with care thereafter.
Causes of loss include those considered below.
- Fermentation, with losses beginning as soon as the crop is mown. Enzymatic oxidation of the sap and the activity of bacteria and moulds on the crop surface cause losses, with generation of heat. If the crop is not aerated sufficiently to dissipate the heat, serious damage can occur. Turning and tedding must therefore be prompt and adequate.
- Mechanical leaf loss occurs during tedding and field handling.
- Leaching losses occurs if rain falls on the crop during the curing process. Re-wetting of partially dried hay is much more serious than rain on newly-cut herbage, and can cause both leaching and increased mould damage. Should rain be imminent on a partially-dried crop, it should, if possible, be gathered into bigger windrows or cocks.
- Further mechanical loss occurs during collection, transport and baling. Their severity depends partly on the skill of the operator.
- Spoilage in the stack or bale is particularly dangerous, and can lead to the loss of the entire harvest, usually as a result of storing material which is at too high a moisture content in over-large units or poorly designed stacks which allow rain penetration or do not allow some ventilation. The ideal moisture content for stacking or baling depends on the crop and the site, and experience and field judgement must be the general guide. The farmer must judge by feel and make a decision in the light of the prevailing weather: when the herbage feels crisp in the hand and does not show moisture when twisted, it is probably at 25 - 30% moisture and ready to bale. Moisture meters are not generally available nor convenient to use in the field, and taking a representative sample is not easy. Fine-leaved, thin-stemmed herbage dries most quickly; large coarse grasses with thick stems and nodes (e.g., Sudan grass) can still have a lot of juice in the stems after the leaves are quite dry. In extreme cases, the fermentation may raise temperatures to levels where spontaneous combustion occurs. Poorly cured or mouldy hay, apart from losses, will lead to poor intake or refusal by stock, and may contain mycotoxins. Mouldy hay gives rise to the human disease known as "farmers' lung."
- Wastage during utilization includes losses from opened stacks and poor feeding techniques. It is dealt with in Chapter X.
Hay preservatives
Several proprietary preservatives are now available; their purpose is to allow hay to be stored at elevated moisture levels that in the absence of preservative would result in severe deterioration or moulding. Hay of 40 - 50% can be stored. Propionic acid is one of the substances used. Anhydrous ammonia or urea treatment, which was originally developed for improving the digestibility of straw, has given good results in hay by improving its stability under anaerobic conditions, as well as improving its nutritive value. The ammonia, in addition to excluding air, has a fungicidal effect, and also increases the crude protein content of the hay. This is discussed in Chapter IX, where the treatment of straws and stovers is described.
Timing of harvest and stage of growth
Two main factors determine the timing of haymaking: the expected weather of the season and the stage of maturity of the crop. Usually the season will be pre-determined by potential availability of herbage and the likelihood of suitable haymaking weather. Pasture, natural or sown, will be managed, by grazing or taking silage cuts as necessary, so that the herbage reaches a suitable stage for curing when good weather is expected. Where sown forage is to be cured, the crop will be chosen and its cultivation organized to match good haymaking weather. If a farm intends to make a lot of hay, consideration must be given to growing a range of species and cultivars to extend the season during which the various crops will be in peak condition for haymaking, and thus make best use of the available equipment and labour.
All steps in haymaking should aim at producing as high a quality of product as possible, but the stage of maturity of the crop is the major factor determining the quality of the final product. Herbage quality drops off rapidly with increasing maturity, especially after flowering, but very young, leafy grass is less easy to handle than more mature herbage, and its yield is less. A compromise between yield and quality has to be made, and, usually, cutting at early to mid-flowering will give a reasonable product. Where tripod drying or barn-drying facilities are available, a younger product can be dried. In "good" haymaking climates, younger material can be cured more successfully than in areas with moist climates, or where there is danger of tropical storms. Cereals for hay are cut at a more mature stage than are pasture grasses, often when the grains are fully formed. Hay from natural pasture is more influenced by the natural growth cycle than are sown crops, and harvesting seasons are often traditional. Many hay meadows rely on natural fertility rather than applied fertilizer, so there is often only one period in the year when they carry sufficient herbage for haymaking.
The time of year depends on the availability of suitable herbage and the weather pattern. The rest of the farming cycle and availability of labour and machinery of course also have a determining role. The aim is always to have both high-quality herbage and a high probability of suitable haymaking weather coincide. Where there is an overall scarcity of forage, farmers may make hay even when the quality of the crop is poor. For example, in the monsoonal tropics and subtropics, a lot of hay is made from very over-mature herbage because the weather during the season when the grass is at its best quality is unsuitable for drying. The product is poor, but even hay which is no better than straw is highly valued. Examples are given in the case studies on Afghanistan, India, Pakistan and the Sahel.
The time of day to start is equally weather dependent, but if the day dawns fair, it is best to mow as early as possible. If the crop is very wet due to previous rain or heavy dew, it may be advantageous to wait an hour or two while the upper part of the crop dries somewhat, since standing grass will dry more quickly than a cut swath. Mowing should not, however, be put off too long, especially under tropical conditions, where afternoon showers are usual. If cut early, the crop can often be turned and windrowed in a morning, before the afternoon rain. Where the scythe is used for mowing, it is everywhere agreed that it is best to start while there is still dew on the herbage, since this greatly facilitates mowing. For haymaking by sickle, however, Skerman and Riveros (FAO, 1989) recommend waiting until the dew has dried. Early mowing allows the other operations, especially turning, to start early and increases the chances of having drying well advanced during the first day.
Deciding whether or not to mow on any given morning may be a problem. In arid areas and climates with a fairly definite dry season (e.g., making oat hay in the North African late spring, or irrigated fodder in arid areas) there is little difficulty. In uncertain climates, however, it is necessary to assess whether there will be a spell of good weather sufficient to allow the making of hay safely, or at least to be able to get it into large windrows. Local weather forecasts, as well as experience, will help, as the time required to cure hay varies greatly with site and climate. In good tropical and subtropical conditions, it can be cut and cured the same day; under humid temperate conditions, several days of good weather are required. In the UK, hay is rarely made in under three days. Delay once the crop has reached a suitable stage of maturity will, of course, reduce the likelihood of producing high-quality hay. Mowing when there is a possibility that poor drying weather will hamper curing may lead to slow drying, long periods in the field, rain damage and possible mouldiness. The final decision is one which requires all the farmers' experience and skill, but in a case of indecision it is probably better to mow than to put off.
The number of cuts per year varies greatly. On natural pasture, only one cut from the spring or summer flush is usually possible (unless the herbage is greatly modified by fertilizer). Sown pasture and fodder may provide several cuts. For pasture, alternate grazing and mowing (for either hay or silage) is often used, according to the needs of the herd and the weather at the time when a surplus to conserve is available. Hay can only be made when forage is available at the right stage and suitable drying weather is available! Irrigated crops in semi-arid areas have good haymaking conditions and cutting should be organized to maximize production while maintaining quality through frequent cuts. This is especially important for the major irrigated forage, lucerne, and details are given in Chapters III to VI. In warm, irrigated areas, cuts may be almost monthly.
Haymaking
Haymaking requires rapid action to take advantage of such good weather as is available, to make the best use of the equipment, labour and power available, and to synchronize and complete the multiple tasks involved. The amount cut should match the capacity for conditioning, tedding and baling, so that each part of the field is dealt with as it reaches the required moisture content.
General principles
All activities in haymaking must be done on time, from mowing, through turning, to windrowing and baling or stacking, otherwise the crop will spoil. At no point until it is won can mown hay be left. The amount mown daily must therefore correspond to the labour and machinery available for all the other activities that must follow. Mowing should be so organized as to minimize turning and "empty" time for the mower, and to facilitate subsequent operations. Whatever machine is used for tedding or windrowing, it is best to follow the mower round the field in the same direction when the swaths are first moved. If conditioning is done, it should be at, or immediately after, mowing, as should be the first turning to improve aeration and speed up drying.
Under good conditions, the made hay can be carted from the windrow after one or more turnings. The time involved varies greatly according to climate, weather and crop. In dry, warm subtropical conditions, hay can be trussed, baled or carted on the day of its cutting, and indeed may have to be in order to avoid undue leaf-loss through shattering.
Figure 3. Shaftal (Trifolium resupinatum) drying on a
rammed-earth surface. Note the local sickle; the brush is for recovering
shattered leaves (Ghazni, Afghanistan)
Practice and equipment
Agronomic details of crop installation and management are dealt with at length in Chapters III and IV, but it is worth repeating that careful land levelling, at sowing and where necessary between mowings, is essential. Where frosts occur, heavy rolling in spring of fields with stones and pebbles on the surface is very worthwhile for protecting mowers. Heavy applications of nitrogenous fertilizers are limited by increasing density of sward, which hinders drying and can cause lodging, with subsequent harvesting difficulties and losses.
Damage by wheel traffic can lead to severe reductions in stand production and life, either through soil compaction or, especially in lucerne, by damaging crowns and re-growth when field operations are delayed. The lightest equipment compatible with the task should be used; mown herbage should be removed as soon as its condition allows and unnecessary passage on the field avoided. Great longevity of lucerne stands is claimed in some small-scale farming areas (Afghanistan, northern Pakistan) where all operations are manual. Could this in part be due to absence of damage by wheeled implements?
Manual haymaking
Mowing
Until the middle of the nineteenth century, all hay was hand mown. There are two basic hand tools: the sickle and the scythe.
Sickles are designed for cutting cereals, but are poorly adapted to mowing hay, and very slow and laborious in comparison to the scythe. They are, nevertheless, widely used, especially in India and Pakistan, often in a blunt, saw-edged version. Where farms are very small and haymaking a secondary task, equipment is kept to a minimum.
The scythe is the traditional grass-cutting tool of northern Asia and Europe. It can mow at about five times the speed of the sickle. It requires a sward which is reasonably free from obstacles, must be kept very sharp by regular whetting throughout the day, and requires some skill to use. A scythe cuts wheat faster than a sickle, but it does not leave bunches ready to tie. Where the preference in cereal harvesting is for the sickle, small-scale farmers seem loath to acquire additional cutting tools for the minor hay crop.
Table 1. Time taken for haymaking operations in Cameroun
|
Activity
|
Per hectare
|
Per tonne of dry matter
|
Tractor size
| |||
|
Time (hours)
|
Fuel (litres).
|
Time (hours)
|
Fuel (litres)
|
(horsepower)
| ||
| Hand cutting with machete |
12.5
|
-
|
3.1
|
-
|
-
| |
| Scything |
6
|
-
|
1.5
|
-
|
-
| |
| Mowing - cutter-bar |
2.5 - 4
|
10 - 20
|
0.6 - 0.8
|
2.7 - 4.5
|
40 - 80
| |
| Mowing - disc |
2 - 3
|
12 - 18
|
0.4 - 0.6
|
3.0 - 3.6
|
40 - 80
| |
| Mechanical turning |
1 - 1.5
|
6 - 9
|
0.25 - 0.3
|
1.5 - 1.8
|
80
| |
| Windrowing - by pitchfork |
33
|
-
|
8.3
|
-
|
-
| |
| - by star-wheel |
1 - 1.5
|
6 - 9
|
0.25 - 0.3
|
1.5 - 1.8
|
80
| |
| Stacking by hand |
25
|
-
|
6
|
-
|
-
| |
| Baling |
1.5 - 2
|
9 - 15
|
0.4
|
2.2 - 3
|
80
| |
Source: Adapted from IEMVT, 1992, who quote Rippenstein, 1977.
Figure 4. Types of sickle
Source: FAO, 1969: 102.
In Africa, the machete (panga) is the all-purpose cutting tool and may be used for mowing. Data from Cameroun (Table 1) indicates that the scythe was only twice as fast as the panga for mowing but that may indicate greater familiarity with the local tool. The Argentine Chaco case study also mentions mowing with a machete.
Sickles come in a wide range of forms, and two types of blade edge: serrated or smooth. The blade may be semicircular, straight or slightly curved; it is usually inserted into a wooden handle by a tang; some have the blade attached to a metal shaft with a wooden handle. The section on fodder conservation in India mentions an unusual yak-horn sickle used in Ladakh. Cutting cereals with a sickle is very slow, but it allows careful reaping and avoids shattering of the ear; this, and its low cost, accounts for its continuing popularity with small-scale farmers. For mowing grass in substantial quantities, the sickle is slow and tiring, so it does not encourage any serious effort to cut forage and make hay in regions where it is the only available harvesting tool. It is a cheap, simple tool and is still very widely used all over the world. Sickle-cut hay is usually handled in bundles from the time of cutting, and is often carried to the homestead for final drying. The individual amounts are usually small, but, in aggregate, a great deal of hay is made this way, especially from irrigated lucerne in western and central Asia and from natural herbage in the monsoon zone. With a tool which is so clumsy, and often blunt, the herbage is usually pulled and cut at ground level; this damages some crops, especially lucerne, and every effort should be made to encourage cutting above the level of the young shoots which provide the next crop. Haymaking is very widespread in Afghanistan and the traditional sickle, used for clover and lucerne, is long-shanked and smooth-edged, often with a long handle. It is kept sharp and wielded one-handed with a scything motion, and works better and faster on lush legumes than would a grain sickle.
The scythe is essentially a grass-mowing implement, worked with two hands. It consists of a blade joined to a handle (the "snath" or "snead") by a ring connector. Two quite different types of blades are used: ground blades (sharpened on a grindstone) and hammered blades (sharpened with a hammer and small anvil). Both are finished off with a whet-stone, which is also used to keep the blade sharp in the field. Ground blades, the older type, are used in northern Europe and North America, whereas the hammered type, developed in Austria, are used in central and southern Europe, and have spread to Latin America. Whetting is the sharpening of the blade, in the field, by special stones (some require water if the herbage is dry) which are stroked over both sides of the blade, starting from the heel.
The blade, of mild steel, has a reinforced back, the end of which forms the tang for connection to the snead. Its length for mowing cereals and herbage is 75 - 100 cm (shorter blades are used for brush-cutting); longer blades require more skill in operation and a stone-free field surface. The width of the blade at the heel is 10 cm or less for mowing, but may be wider for dealing with thick-stemmed material. Sneads are traditionally of wood, although light metal tubes are now also used. The handle of the traditional type is long and has a grip in its middle for the right hand; some have a second grip at the top; an improved type used in Scotland has a Y-shaped snead with two grips.
Figure 5. Mowing by scythe
Source: FAO, 1969: 113.
Sneads vary considerably in design, but are designed to allow the operator to mow with outstretched arms and both hands on more or less the same horizontal plane so that the implement can be swung through a wide semicircle with the blade always parallel to the ground and without undue strain. The length of the snead and the position of the grip(s) should be determined by the height of the user. The blade is attached to the snead by a ring-connector which is fixed by a screw or wedge; this makes it possible to regulate the angle between the blade and the snead. The vertical alignment of the blade can be regulated, by a blacksmith, through modifying the angle of the tang to the blade-back.
Grass, especially thin stands of natural hay, is much easier to mow with a scythe in the morning when the dew is still on it. Scythes are frequently recommended in new areas where hay is being popularized, often with little success; the reason may be that the art of scything, in the western world, is largely forgotten and few technicians now have the necessary expertise to effectively demonstrate this arduous and skilled task, including scythe maintenance. Mowing with a scythe is a skilled job, and very different from cutting with a sickle. Forage crops are mown with wide cuts, advancing in a straight line and cutting away from the standing crop. A scythe cuts about 2½ times the length of the blade, so a 75 cm one will mow a swath 175 cm wide if the crop is not too heavy, with the width reduced in a denser crop. On good, level, stone-free ground, about 500 m2 can be mown per hour.
Turning and tedding
Like mowing, windrowing and turning was done by hand until relatively recently Various home- or locally-made wooden forks and rakes were used, and are still common. Turning by hand, without tools, is not uncommon, but very laborious. Metal-tined forks came in latterly. The fork is used for all manipulation of hay during loading and stacking. Herbage may be taken to the homestead for final curing, in a place where it is out of the way of livestock. There are several reasons for homestead drying, including the availability of suitable drying areas, convenience for turning and handling small quantities without having to travel to the field (which may be at some distance in the case of natural herbage in mountainous areas), and also the possibility of theft from the field. Examples of this fairly widespread system are given in the case studies on Afghanistan, Liaoning and Pakistan. Small quantities are often stored on rooftops, in trees and around farm buildings in traditional systems, often to keep it out of the reach of foraging livestock.
Where drying is slow and weather uncertain, the hay can be put into cocks by hand for several days; it may also be cocked when rain is imminent and then re-spread following the rain. Intermediate stacking in large cocks with a central wooden tripod for ventilation was once common in northern Britain for completing field drying before final stacking. Cocks and large windrows are also used in hot, dry areas to avoid shattering and sun bleaching.
Baling started as trussing - hand rolling into bundles - a practice still common in some areas where natural grass is traditionally mown. Small trusses are widely used for legume hay in semi-arid areas of Asia as a means of reducing leaf-loss. In the case studies, trussing is reported from Argentina as well as most countries in semi-arid Asia. Stationary hand presses were developed where hay and straw had to be transported over long distances; they are still used in some areas, as reported in the case study on the Argentine Chaco.
Figure 6. Hand-trussed lucerne drying on bunds (Herat,
Afghanistan)
Figure 7. Further drying of lucerne trusses in a loose stack
(Herat, Afghanistan)
Transport was the first operation in haymaking to be mechanized - long before mowing - and animal-drawn carts have long been used. In order to better carry the bulky loads, frames are added at haymaking in order to increase the carts' area. Pack-saddles are also used, as well as back-frames and ropes for porters, mainly on land too steep for or inaccessible to wheeled vehicles. When transported by cart, the hay is usually loaded by pitchfork and carefully built on the wagon: the corners should be laid down first, then the sides, and finally the centre, layer by layer, taking care to see that each forkful locks the previous one. Carting high, bulky loads on sloping land is not easy; if the land is at all steep it may be necessary to work with the slope, and this should be taken into account when windrowing the crop.
Haymaking using draught animal power
Mowing
Horse-drawn reciprocating-blade mowers were introduced in the early nineteenth century in the USA and soon became the main grass-cutting machine of large-scale agriculture. The mower has a main frame, with a seat for the operator, mounted on two wheels, from which power is transmitted through a live axle and differential gears to the cutting mechanism. The gears of the differential drive run in an oil-bath. The cutting mechanism is connected to the main frame by a double-jointed drag bar which allows adjustment of the cutter bar by levers. A crankshaft and connecting rod (pitman) transform rotary motion into reciprocation. The cutter bar is usually 1.25 m or more long, carrying ledger plates with "fingers" which form half the scissors. The cutting action is completed by the reciprocating knife bar with triangular blades. Knife sections are easily removable by punching out two rivets and inserting new pieces. There is a prolonged swath-board at the end of the bar to lay the mown herbage away from the standing crop.
These mowers are of relatively simple construction and can be maintained and repaired by elementary workshops, but require clean fields and the blades must be sharpened regularly. It is essential that the ledger plates of all fingers be in alignment so that the knife sections slide over them smoothly. The cutter bar is in proper alignment when the crank-pin, the knife head and the outer end of the knife are all in line. Cutter bars and knives are exchangeable. This type of mower has a power requirement of 1.5 kW per metre of cut, and forward speeds of 3 to 8 km/hr are suitable. It is the only type of mower which can be drawn by livestock.
The mower is usually drawn by two animals and enough will be mown at any one time to suit the rest of the handling equipment and labour. The swath should be turned by hand, or star-wheel rake if available, soon after mowing. Further handling will either be manual or by simple equipment. A dump-rake is very useful for forming windrows and gathering the hay for carting. Carting and stacking is as for manual haymaking (see above).
Swath manipulation
Turning and tedding is often by hand, although horse-drawn dump-rakes, sweeps and tedding machines were developed in parallel with mowers, and later adapted to mechanical traction. The dump rake (Figure 9) is the commonest and most useful implement; it consists of a large number of long, slightly curved teeth on a bar parallel to its axle, with a pawl and ratchet mechanism for tripping the rake, worked by a foot pedal by the operator sitting on a seat and guiding the horse. It is used for dragging hay into windrows and for cleaning hay and corn stubble.
Figure 8. Horse-drawn mower (Altai, Xinjiang, China)
Figure 9. Dump rake, windrowing newly-mown lucerne, (Altai,
Xinjiang, China)
Cocks, tripods and rack-drying
Where there is danger of re-wetting, which is very damaging, there is an intermediate stage where the partially-dried herbage is put into small heaps - "cocks" - to dry further with less danger of rain affecting the whole mass. Under sub-optimal conditions, the cocks may be built on wooden tripods to improve ventilation, or the hay may be put on drying racks - all labour-costly operations. They are also useful in hot dry areas where the best quality hay is made by putting it up in cocks, which reduces both shattering and weathering and produces a green, leafy hay high in carotene. Racks and tripods, however, require a cheap supply of poles, not always readily found. Fully mechanized systems attain a similar effect through careful swath handling and windrowing. IEMVT (1992) describe and recommend several drying structures for small-scale farming use. These include a "Canadian tent," which is built from two A-frames with a ridge pole and one or more poles on the sides; tripods; and a "Scandinavian fence" of posts and wire.
Figure 10. Hay being taken to market, above Lhasa, Xizang,
China. The climate of the plateau is too harsh for cultivated fodder but some
Pennisetum flaccidum reaches mowable height in protected places
Collection, loading and transport
Horse-drawn sweeps were developed to push several sections of windrow together for ease of collection, and some have a tumbling action so that they discharge easily. Cranes were also used for loading hay onto wagons or from wagon to stack, and in the field they were especially useful where intermediate on-field stacking was used. Such equipment was used on large farms, and these are now highly mechanized. In small-scale farming systems, loading is by fork and hay is transported on carts, which may be temporarily modified by the addition of frames to increase their base area to allow transport of a greater load of bulky material.
Simple mechanization
Small tractors are becoming increasingly common in developing countries, and often their owners do some contract work as well as tending their own farms. Old and simple techniques of mowing and sward handling can be introduced with a minimum of equipment and investment, but can speed up and improve haymaking a great deal. A mower, dump rake and some frames to expand the loading area of existing trailers will go a long way toward mechanizing the hay harvest. In the case study on Altai, for example, a centrally-run machine pool with heavy equipment proved less attractive than simple mechanization run by farmer-contractors with the kind of equipment mentioned above.
Mowing
When tractors came into use, reciprocating mowers were adapted to suit them; the first, trailed models worked from the ground wheels, and then mounted models evolved, driven from the tractor's power take-off (PTO). Of the PTO-driven models, mid mounted bars are by far the simplest to work with since the bar and control are in front of the driver and the drawbar is free for other equipment. The close-coupled arrangement allows square cornering. The reciprocating mower's power requirement is about 1.5 kW per metre of cut, and a forward speed of 3 to 8 km/hr gives a rate of 0.2 - 0.6 ha/hr for a 1.5 m cut. Over a season, the work will be about 50% of that "spot" rate.
Figure 11. Rear-mounted disc-mower (Altai, Xinjiang,
China)
Swath manipulation
Dump-rakes have been adapted to be drawn by tractors. Finger wheel machines are simple and light implements; they are gear-less. A number of independently mounted large diameter wheels with spring teeth arranged radially are set in an oblique frame. The wheels, which gain their motion from contact with the ground, are free to float and overlap each other. When the wheels are on a single bar, they act as a side-delivery windrower. On double bar machines, the wheels can be arranged in two banks, one before the other for swath turning.
Stationary ram-balers (powered by tractor or engine) were developed for use where hay or straw had to be transported. These have been replaced on larger farms by pick-up balers, but are still used in conjunction with animal drawn and other simple methods of haymaking. The case study on Pakistan mentions that straw is baled for transport to the large cities.
Modern systems
Many levels of equipment and sophistication are now available. With a light tractor, such as those commonly found in small-scale farming areas, and some simple raking or turning equipment, the system will be little different, although quicker, from haymaking by draught animal power. Where fields are large and heavy equipment available, specialized equipment will be used and the hay will usually be baled in the field and stored as bales. The mechanization of haymaking, baling and handling is now highly developed.
Mowing
The mower should be able to cut the forage to be handled in a day. A speed of 15 km/hr with a narrow cut of 1.8 m will cut 1.5 to 2 ha/hr. For high output, 2 to 3 m-wide cuts are possible, but the swath should be gathered to 1.6 m to allow passage between tractor wheels and match subsequent equipment; the drying rate is reduced by this thicker row. The mower should be capable of operating continuously, without blockage even in dense and laid crops. Less than 25% of the time should be taken up by turning, travel between fields, delays and adjustments. When there are stones, etc., adjust the mower to cut above them, say 4 cm above the soil. The traditional cutter bar mower was described above. The "finger-less double-knife" mower is less susceptible to blocking, but needs special sharpening equipment. They can work at 10 to 14 km/hr and mow 6 to 10 ha between sharpenings. Self-propelled mower-windrowers, with the cutter bar at the front, are now also available.
Disc mowers
Disc mowers, which have a cutter-bar fitted with two to six rapidly rotating discs, are a more modern tool and stand up much better to situations of poor field levelling and coarse herbage (Figure 11). Their action has a more bruising effect on the herbage than does the reciprocating knife, so the hay dries more quickly. With a power requirement of 7 to 15 kW per metre of cut (this power requirement can double when the machine is worn or cutters blunt) and a forward speed of 10 to 15 km/hr, a tractor of 35 hp (26 kW) is required for a four-disc model. Disc mowers are unsuitable for animal draught. Disc mowers are unlikely to block in laid or heavy crops. Knife maintenance is simple, and a set of knives will last 40 ha under reasonable conditions. Attention must be given to knife height as well as to the fore-and-aft setting of the cutter unit. Disc mowers can operate at up to 16 km/hr, but 10 to 13 km/hr is more practical. Their working rate is 0.5 to 1.5 ha/hr per metre of cut. Double-drum mowers are now widespread in western Europe.
Conditioners
The aim of conditioning is to reduce the period when the crop is at risk; it should not only increase the drying rate but should also encourage even drying. Conditioning is, of course, only really effective when conditions are suited to removing the moisture thus made accessible. Machine conditioning usually leads to some nutrient loss through breakage. Conditioning is most effective when done at cutting or immediately afterwards; it is usually achieved by either crushing or crimping. Crushing is done by passing the crop between plain or fluted rollers; crimping may crush, but also bends the herbage at 5 to 10 cm intervals and may bruise leaves. Modern equipment includes mower-conditioners that partially crush the sward, as well as cutting it, thus accelerating drying. Early mower-conditioners were designed for lucerne in the USA and comprised a mower followed by crushing or crimping rollers. They work well in a medium crop, but not in a heavy one under European conditions. In Europe, drum or disc mowers, 1.5 to 3 m wide, followed by intermeshing rollers, are used but, increasingly, overshot tedders which abrade the herbage against a concave as it passes are commonly used in conjunction with drum mowers.
Swath handling
Tedding immediately after mowing boosts the drying rate. Conditioning or crushing should be done within twenty minutes of mowing. Timing of swath handling is critical and, at a time of peak demand for traction and labour, it is desirable to have a machine with a high work rate and a low power demand. It should have a wide working width and follow the land surface well to ensure that the maximum of the crop is properly treated. Most modern machines use configurations of tines moving in a near-horizontal plane, and some have drums to deliver the crop to one side. If a large windrow is required, the machine can be driven in alternate directions to combine two rows together. Overshot tedders are increasingly used. They have a series of flails on a horizontal axis, which pick up and aerate the swath. Some machines combine several functions and can ted, spread or windrow, depending on the position of the crop-directing cage. Machines for pick-up in line with the tractor, such as balers, must have a swath of uniform cross section.
In cool, temperate conditions the swath has to be raised for aeration. Under hot, dry conditions, it may be beneficial to spread it over the greatest possible area to benefit from the sun. In most temperate situations it is necessary, however, to tease out, mix and turn the swath as drying proceeds. Unless the weather is warm and sunny, the swath should be set up to catch any air movement across the field. Both crimpers and conditioners are designed to set up the swath and assist air movement. If rain falls on a windrow prepared for baling, the windrow should be split into its original parts as quickly as possible, or drying will be very slow. In very hot, arid conditions, too-rapid drying of the leaves leads to shattering and bleaching, but windrowing will palliate this. Drying can be speeded up by collecting the half-dried hay into narrow, compact rows overnight, and spreading it out over all the ground once the soil between the rows has dried in the morning. The swath must always be collected into windrows for carting or baling. Speed of baling depends greatly on the type of windrow presented to the pick-up reel.
Bales and balers
Pick-up baling is now the norm in most mechanized haymaking. Two basic types of bale are made: the standard rectangular bale, which can be handled manually, and the, usually cylindrical, "big bale" of about 500 kg, which is handled using the tractor's front-end loader. A "standard" bale is nominally 36 cm ´ 46 cm ´ 90 cm, and weighs 15 to 25 kg, according to the density of the bale and the moisture content of the hay. It is suitable for manhandling and provides a hay ration for four to ten dairy cows. Such bales are useful when small quantities of hay are needed some distance from the store or in buildings not adapted for mechanized handling.
There are two types of standard balers. Most are of the slicing ram type, in which the reciprocating ram that compresses the forage in the bale chamber is fitted with a knife to slice through the herbage at the end of each stroke. If the knife is properly maintained and set, then slices which can be separated will be formed. Bale density can be adjusted from 80 kg/m3 to 220 kg/m3 by adjustment of spring-loaded plates. On most balers, the length of the bale can be adjusted over a range of between 1½ and 2 times the bale width. The swinging ram, or press baler, has a folding action in which the successive charges are not cut. Under similar crop and conditions, it produces a less tidy bale, usually of a lower density than does the slicing-ram baler. Such bales have an advantage, however, in that air can penetrate them more readily and give better ventilation, which is useful in handling a crop with high moisture content.
The pick-up of a baler should be wide enough to deal with a heavy crop; preferably able to take a swath of over 1.5 m width. A combination of narrowly spaced pick-up tines, a freely-floating pick-up wheel and a spring-loaded guide is most likely to pick up cleanly. The flow of the crop from pick-up to bale chamber must be free of obstructions. Easy adjustment of packers is necessary if well-shaped bales are to be produced. If the feed is uneven, the bale will curve away from the denser side and binding strings may become detached.
Knotters should be able to handle a range of twines. Full out-of-season maintenance of the baler, and its knotter, is very necessary.
The machine must be adjusted according to the type and moisture content of the hay, which will vary according to the time of day and position in the field, so continual operator attention is essential. Moist hay gives heavy bales, which may burst the strings if too dense and/or too large. Light, stemmy hay gives light bales with loose strings. Bales should be examined for moisture content and shape as they leave the chamber. In the UK, hay is baled at 20 to 35% moisture, with the higher levels intended for subsequent barn drying. High-moisture-content bales should be made shorter than dry ones. The output of balers varies between 3.5 and 10 t/hr, but is usually around 6 to 7.5 t/hr or 1 ha/hr. Mechanization of loading and handling is by trailing wagon, or systems which, for weather protection in the field, group bales into pyramids of 3 to 15.
The activities involved in handling standard bales are grouping, loading onto transport, unloading, and loading into the store. If carting directly from the baler to the store is possible, then that is ideal, but this is not often the case. Small stacks of bales are often made in the field for a holding period or under temporary cover; the hay is partially protected from the weather while the heat from oxidation and some moisture is dissipated. Field stacking separates the handling into stages in the event of labour scarcity. The shape and size of the heaps should be decided on as an integral part of the handling system, and must not reduce baler output. Stack size is related to field size and topography, as well as to building size and layout. It is necessary to estimate how much hay will have to be handled in unit time to avoid spoilage between baling and storage. Single bales can be picked up from rows and loaded directly on to trailers (180 bales per person per hour). Hydraulically operated swinging-arm loaders can tumble-load about 400 bales/hr. A team of three with such methods can haul and store up to 200 bales/hr, or 70 bales per person per hour, which is double the hand-loading rate. Extended chutes and throwers attached to the rear of the bale-chamber allow rapid clearing of the field, but require a lot of trailers. Stacking the bales on a trailer is hard work, and if the labour does not keep up, then baling is delayed. Turning time is greatly increased with such a long train of equipment.
Single bales, as dropped by the baler, are very susceptible to damage from heavy rainfall, and also interfere with the re-growth of the crop if left more than a few days. It is common to collect bales into groups, which are often made into small intermediate stacks in lines or on headlands. If the tops of the stacks are protected - such as by plastic sheeting, tarpaulin (Figure 12) or thatching - they can be kept safely in the field for some time. Plastic covers should be removed periodically to allow condensation to dissipate. Collection after the baler using manned sledges usually slows baler operation. Automated systems, such as random collectors and fully automatic bale collectors, which collect bales and form groups which can be picked up by the loader without further handling, eliminate the need to form them into units by hand. The simplest arrange bales into flat units of eight to ten.
Big bales
There are two main types of large round balers. Fixed-chamber balers have a chamber of a fixed diameter; in the initial stages hay is packed at random, then a rolling action starts when hay comes into contact with the bale-forming mechanism (rollers or chains and slats). This completes the bale with a spiral of compressed, roughly aligned crop. The outer layers of these bales are denser than the core, and bale size is predetermined by the size of the chamber.
In variable-chamber balers, the bale-forming mechanism expands with the bale, which is thus subjected to continuous rolling. Bale size can be determined by tying at almost any stage of the process.
Big balers come in sizes ranging from 0.9 m diameter by 1.2 m length, to 1.8 m diameter and 1.5 m length. Bale density is commonly between 110 and 120 kg/m3.
Figure 12. Standard hay bales covered by a tarpaulin, drying
in a humid climate (Alford, Scotland)
Figure 13. Big hay bales drying as they landed in the field,
but spoiling re-growth. (Dunecht, Scotland)
Big balers are relatively simple in operation and construction, but the shape and stability of the bales depends greatly on the shape of the windrow picked up and the skill of the operator. The crop to be baled should be drier than for standard baling, and preferably less than 18% moisture. Bales are wrapped with thin twine and then ejected, and the tying can take 30 - 40% of baling time. Their working rate is 6 - 10 t/hr, depending on the crop and bale size. Bales are left in the field to aerate before they are stored, as artificial drying is not easy. Big bales are greatly used as a means of storing straw, especially for later ammonia treatment. Big bales, which are handled at all times using the front-end loader, should be removed from the field as quickly as possible after baling to avoid damage to the crop, and placed, singly, on their sides in a suitable storage area with a space between adjacent bales. When storing bales, keep in mind the state of the site throughout the year, and not just at the time of harvest.
Storage
Hay can be kept for long periods if properly made and correctly stored; in contrast, it can deteriorate rapidly and even be lost by careless storage. The aim in storing hay is to keep it dry and to protect it from wastage due to rots, pests, stray livestock, fire or wind.
Storage areas, whether stack-yards or for bales, should have a dry foundation throughout the year, not only at the season of storage. They should be accessible all year round to the type of transport used, and protected from stray livestock and any fire risk. Where possible, it is better to store close to the point of use rather than in the field. Barn storage is ideal, of course, but is not always feasible.
Stacking
Stacks of loose material are the traditional method of storing large quantities of hay and, apart from barn storage, were the principal system on large as well as small farms until the introduction of the pick-up baler revolutionized commercial haymaking.
Once the hay has been field-dried to a suitable stage, it is carted to the stack-yard and built into stacks. The hay must be carefully built on to carts in the field and taken off in the same order as it was loaded. Under no circumstances should it be tipped off the cart if it has to be hand-forked to the stack, as random hay is very difficult to pull from the heap. Stacking is a skilled job and the quality and safety of the harvest depends heavily on the skill of the builder, especially in regions of moderate to high rainfall. Stacks may be cylindrical or rectangular in section, depending on the quantities involved and the condition of the hay. Often they are built on a base of loose stone for aeration, and in humid-temperate zones a central wooden tripod can be put at the centre of cylindrical stacks for aeration. Skerman and Riveros (FAO, 1989) recommend stacking on a base of hardwood poles, but this will depend on availability and price. When building the stack, the centre must be tightly packed, otherwise the stack will sag as it settles and rain may penetrate. The sides should slope outwards slightly to the eaves and the head thereafter rise gently to a point or ridge. Ropes or nets are used to protect the stacks against wind. Thatching with coarse grass or straw is common in areas where rain is expected during storage. This should not be done immediately, because it is necessary to allow dissipation of heat and moisture following stacking.
The yard must be kept tidy throughout stacking and storage, and vermin such as rats should be eliminated if possible. Apart from the damage they may do, rodents in stacks in warm areas attract snakes, which can be distracting to the labour when the hay has to be taken out for livestock feeding. Termites are another possible cause of damage. In areas subject to high winds, windbreaks, such as earth walls, have to be constructed, else it is not possible to store hay in the open. In severe cases, the stack may be no higher than the windbreak.
Mud-plastered stacks are traditional in areas where straw is chopped at the time of threshing, and are described in the case studies. This system does not appear to be used for hay. Storage of hay and straw in the forks of trees is widespread, especially for straw, in order to keep it out of reach of wandering livestock.
House-top storage is very common on smallholdings in semi-arid areas where flat-roofed houses are traditional; the house roof is often used as a drying area for other crops, as well as hay. In areas of negligible precipitation, this is an excellent storage method, but where there is rain the hay will be damaged by weathering. One reason for using the roof top is, of course, to keep the hay out of the reach of livestock around the homestead; another reason may be added insulation. This system has an inherent fire risk.
In parts of India and Nepal, terai wooden shelters are commonly constructed near the homestead for milch stock, usually buffaloes. Terai are flat-roofed and serve as storage platforms for straw and hay, as well as protecting the stock from the sun. Some have a protruding central pole to better retain the stored hay or straw.
Figure 14. Hay stacked behind a windbreak (Altai, Xinjiang,
China). In this arid climate, thatching is not needed, but low stacks and
protection from high winds are needed.
Fire Risks
Hay is easily set on fire, as are dry crop residues, so care must be taken in siting stack-yards and storage so as to minimize the risks. Stored hay may be accidentally ignited by household fires, by smokers' carelessness, by sparks from bush fires, and so on. Care in siting, cleanliness - including tidying up of loose hay which could carry fire - and avoidance of smoking or other sources of fire near or in the stack-yard will help prevent accidents. Where dry fodder is stored on or close to houses, extra care is needed. Spontaneous combustion can occur when hay is stored at too high a moisture content.
Arson is another risk: an interesting solution to arson of haystacks, in an area where such a means of settling scores is not uncommon, is given in the case study in eastern Turkey, where the authorities insisted on communal stack-yards - if one burnt all would burn!
Bale storage
Advances in mechanization have concentrated more on clearing the field than handling in the store. Elevators move bales from the trailer to the stack, but the speed of operation does not match field handling systems. A team of three is required to feed an elevator and stack the bales, and such a team will handle about 420 to 500 bales per hour. Where the building layout is suitable, front-end loaders are used for stacking in the store.
Fractionation of legume hay
Traditional ways of separating the leaves and stems of leguminous hays for different uses have been noted in China. The final drying of the hay is usually done in the house compounds, and once really dry, it is beaten lightly, the leaves fall and are separated from the stems. The leaves are high-quality feed and are often reserved for monogastric livestock. When the hay is lucerne, the stems will be used for ruminants (see the Liaoning case study (Case Study 5 in Chapter XI)). In very fuel-deficient areas of the Loess Plateau, both sweet clover (Melilotus spp.) and North China milk-vetch (Astragalus adsurgens) are treated in this way, and the coarse stems used as fuel. This is only done where there is plentiful family labour. A similar technique sometimes is used to collect the leaves of trees and shrubs while still green: the loppings are heaped in a well-ventilated and sunny place and turned, where the leaves fall, are collected and further dried for storage. The remaining branches are used as domestic fuel. Caragana spp. are sometimes treated thus on the Loess Plateau, as are Alhagi spp. in northern Afghanistan. Ziziphus spp. are coppiced and dried in parts of Rajasthan.
Source: http://www.fao.org/docrep/005/X7660E/x7660e06.htm
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