Organic Foods: Understanding Organic Food Labels, Benefits, and Claim

Organic food has become very popular. But navigating the maze of organic food labels, benefits, and claims can be confusing. Is organic food really healthier? Is it more nutritious? What do all the labels mean? Why is it so expensive? This guide can help you make better choices about which organic foods are healthier for you and better for the environment, and how you can afford to incorporate more organic food into your diet.

In This Article:

• What is organic food?
• The benefits of organic food
• Organic farming 
• Organic meat & dairy
• Understanding organic labels
• Cost of organic food 
• Enjoying the benefit of fish without harmful side effects

What is organic food?

Making a commitment to healthy eating is a great start towards a healthier life. Beyond eating more fruits, vegetables, whole grains, and good fats, however, there is the question of food safety, nutrition, and sustainability. How foods are grown or raised can impact both your health and the environment. This brings up the questions: What is the difference between organic foods and conventionally grown foods? Is “organic” always best? What about locally grown foods?

What does “organic” mean?

The term “organic” refers to the way agricultural products are grown and processed. Specific requirements must be met and maintained in order for products to be labeled as "organic".

Organic crops must be grown in safe soil, have no modifications, and must remain separate from conventional products. Farmers are not allowed to use synthetic pesticides, bioengineered genes (GMOs), petroleum-based fertilizers, and sewage sludge-based fertilizers.

What are Genetically Modified Organisms (GMOs)

Genetically Modified Organisms (GMOs) are plants or animals whose DNA has been altered. These products have undergone only short-term testing to determine their effects on humans and the environment.

In most countries, organic products do not contain GMOs.

Organic livestock must have access to the outdoors and be given organic feed. They may not be given antibiotics, growth hormones, or any animal-by-products.

Is organic food more nutritious than non-organic food?

The evidence is unclear. Some studies suggest that, on average, organically grown fruits and vegetables may contain slightly higher levels of vitamin C, trace minerals, and antioxidant phytonutrients than conventionally grown produce. However, other studies have found no nutritional differences between organic and non-organic foods.

The benefits of organic food

Organic foods provide a variety of benefits. Some studies show that organic foods have more beneficial nutrients, such as antioxidants, than their conventionally grown counterparts. In addition, people with allergies to foods, chemicals, or preservatives often find their symptoms lessen or go away when they eat only organic foods. In addition:

• Organic produce contains fewer pesticides. Pesticides are chemicals such as fungicides, herbicides, and insecticides. These chemicals are widely used in conventional agriculture and residues remain on (and in) the food we eat.

Why do pesticides matter?

• Children and fetuses are most vulnerable to pesticide exposure due to their less-developed immune systems and because their bodies and brains are still developing. Exposure at an early age can cause developmental delays, behavioral disorders, and motor dysfunction.
• Pregnant women are more vulnerable due to the added stress pesticides put on their already taxed organs. Plus pesticides can be passed from mother to child in the womb, as well as through breast milk. Some exposures can cause delayed effects on the nervous system, even years after the initial exposure.
• Most of us have an accumulated build-up of pesticide exposure in our bodies due to numerous years of exposure. This chemical "body burden" as it is medically known could lead to health issues such as headaches, birth defects, and added strain on weakened immune systems.

• Organic food is often fresher. Fresh food tastes better. Organic food is usually fresher when eaten because it doesn’t contain preservatives that make it last longer. Organic produce is often (but not always, so watch where it is from) produced on smaller farms near where it is sold.
• Organic farming is better for the environment. Organic farming practices reduce pollution (air, water, soil), conserve water, reduce soil erosion, increase soil fertility, and use less energy. In addition, organic farming is better for birds and small animals as chemical pesticides can make it harder for creatures to reproduce and can even kill them. Farming without pesticides is also better for the people who harvest our food.
• Organically raised animals are NOT given antibiotics, growth hormones, or fed animal byproducts. The use of antibiotics in conventional meat production helps create antibiotic-resistant strains of bacteria. This means that when someone gets sick from these strains they will be less responsive to antibiotic treatment. Not feeding animal byproducts to other animals reduces the risk of mad cow disease (BSE). In addition, the animals are given more space to move around and access to the outdoors, both of which help to keep the animals healthy. The more crowded the conditions, the more likely an animal is to get sick.

Organic farming and locally grown produce

Organic farming refers to the agricultural production systems that are used to produce food and fiber. Organic farmers don’t use synthetic pesticides or fertilizers. Instead, they rely on biological diversity in the field to naturally reduce habitat for pest organisms. Organic farmers also purposefully maintain and replenish the fertility of the soil. All kinds of agricultural products are produced organically, including produce, grains, meat, dairy, eggs, fibers such as cotton, flowers, and processed food products.

Essential characteristics of organic systems include:

• Design and implementation of an "organic system plan" that describes the practices used in producing crops and livestock products.
• Detailed recordkeeping systems that track all products from the field to point of sale.
• Maintenance of buffer zones to prevent inadvertent contamination by synthetic farm chemicals from adjacent conventional fields.

Organic vs. Non-organic Produce
Organic produce: No Pesticides Grown with natural fertilizers (manure, compost). Weeds are controlled naturally (crop rotation, hand weeding, mulching, and tilling). Insects are controlled using natural methods (birds, good insects, traps).	Conventionally grown produce: Pesticides used Grown with synthetic or chemical fertilizers. Weeds are controlled with chemical herbicides. Insecticides are used to manage pests and disease.

Locally Grown Fruits and Vegetables

What is local food? Unlike organic standards, there is no specific definition. Generally local food means food that was grown close to home. This could be in your own garden, your local community, your state, your region, or your country. During large portions of the year it is usually possible to find food grown very close to home at places such as a farmer’s market.

Why people buy locally grown food:

• Financial benefits: Money stays within the community and strengthens the local economy. More money goes directly to the farmer, instead of to things like marketing and distribution.
• Transportation issues: In the U.S., for example, the average distance a meal travels from the farm to the dinner plate is over 1,500 miles. This uses a lot of fossil fuels and emits carbon dioxide into the air. In addition, produce must be picked while still unripe and then gassed to "ripen" it after transport. Or the food is highly processed in factories using preservatives, irradiation, and other means to keep it stable for transport and sale.
• Fresh produce: Local food is the freshest food you can purchase. Fruits and vegetables are harvested when they are ripe and thus full of flavor

Small local farmers often use organic methods but sometimes cannot afford to become certified organic. Visit a farmer’s market and talk with the farmers. Find out how they produce the fruits and vegetables they sell. You can even ask for a farm tour.

Fruits and vegetables where the organic label matters the most
According to the Environmental Working Group, a nonprofit organization that analyzes the results of government pesticide testing in the U.S., the following 12 fruits and vegetables have the highest pesticide levels on average. Because of their high pesticide levels when conventionally grown, it is best to buy these organic:
Apples Bell Peppers Carrots Celery Cherries Grapes (imported)	Kale Lettuce Nectarines Peaches Pears Strawberries

Non-organic fruits and vegetables with low pesticide levels
These conventionally grown fruits and vegetables were found to have the lowest levels of pesticides. Most of these have thicker skin or peel, which naturally protects them better from pests, and which also means their production does not require the use of as many pesticides.
Asparagus Avocado Broccoli Cabbage Corn (sweet) Eggplant Kiwi Mango	Onion Papaya Pineapple Peas (sweet) Sweet Potatoes Tomatoes Watermelon

Does washing and peeling get rid of pesticides?

Rinsing reduces but does not eliminate pesticides. Peeling sometimes helps, but valuable nutrients often go down the drain with the skin. The best approach: eat a varied diet, wash all produce, and buy organic when possible.

Source: Environmental Working Group

Organic meat and dairy

Organic meat, dairy products, and eggs are produced from animals that are fed organic feed and allowed access to the outdoors. They must be kept in living conditions that accommodate the natural behavior of the animals. Ruminants must have access to pasture. Organic livestock and poultry may not be given antibiotics, hormones, or medications in the absence of illness; however, they may be vaccinated against disease. Parasiticide (a substance or agent used to destroy parasites) use is strictly regulated. Livestock diseases and parasites are controlled primarily through preventative measures such as rotational grazing, balanced diet, sanitary housing, and stress reduction.

Organic vs. Conventional Meat and Dairy
Regulations governing meat and dairy farming vary from country to country. In the U.S., these conventionally grown meats and dairy products were found to have the lowest levels of pesticides.
Organic meat and dairy: No antibiotics, hormones, or pesticides are given to animals Livestock are given all organic feed. Disease is prevented with natural methods such as clean housing, rotational grazing, and a healthy diet. Livestock must have access to the outdoors.	Conventionally raised meat and dairy: Typically given antibiotics, hormones and feed grown with pesticides Livestock are given growth hormones for faster growth. Antibiotics and medications are used to prevent livestock disease. Livestock may or may not have access to the outdoors.

What’s in American meat?

It is helpful to understand what the U.S. government allows in feed or to be used in conventional production:

• Dairy cows – antibiotics, pig & chicken byproducts, hormones (for growth), pesticides, sewage sludge
• Beef cows – antibiotics, pig & chicken byproducts, steroids, hormones, pesticides, sewage sludge
• Pigs – antibiotics, animal byproducts, pesticides, sewage sludge, arsenic-based drugs (growth hormones are prohibited)
• Broiler chickens – antibiotics, animal byproducts, pesticides, sewage sludge, arsenic-based drugs (growth hormones are prohibited)
• Egg laying hens – antibiotics, animal byproducts, pesticides, sewage sludge, arsenic-based drugs

Source: Meat, dairy, and eggs buying guide

Understanding organic food labels

What do the food labels such as “organic,” "natural," "free-range," and "non-GMO" really mean? Understanding this terminology is essential when you’re shopping for organic foods.

The most important point to remember is that "natural" does not equal organic. "Natural" is an unregulated term that can be applied by anyone, whereas organic certification means that set production standards have been met. These production standards vary from country to country—in the U.S., for example, only the "USDA Organic" label indicates that a food is certified organic. Similar certification labels are also offered on organic products in other parts of the world, including the European Union, Canada, and Australia.

USDA Certified Organic Food Labels in the U.S.

When you’re shopping for organic foods in the U.S., look for the “USDA Organic” seal. Only foods that are 95 to 100 percent organic can use the USDA Organic label.

• 100% Organic – Foods that are completely organic or made with 100% organic ingredients  may display the USDA seal.
• Organic – Foods that contain at least 95% organic ingredients may display the USDA seal.
• Made with organic ingredients – Foods that contain at least 70% organic ingredients will not display the USDA seal but may list specific organic ingredients on the front of the package.
• Contains organic ingredients – Foods that contain less than 70% organic ingredients will not display the USDA seal but may list specific organic ingredients on the information panel of the package.

Certified Organic Food Labels in other countries

European Union

Australian

Canadian

Meat and dairy labels: other terms you need to know

The organic label is the most regulated term, but when it comes to meat, we often see many other terms used. In order to make informed choices, it is helpful to know what some of these terms mean, although their use can often vary from country to country.

• Natural – In the U.S., this label means “minimally processed” and that the meat can’t have any artificial colors, artificial flavors, preservatives, or any other artificial ingredients in it. Animals can still be given antibiotics or growth enhancers. For example, this term can be applied to all raw cuts of beef since they aren’t processed.
• Grass fed – This term means that the animals are fed solely on a diet of grass or hay. These animals have access to the outdoors. Cattle are naturally ruminants that eat grass, so they tend to be healthier and leaner when fed this way. In addition, grass fed beef has been shown to have more of the healthy omega-3 fatty acids.
• Free range – Again the term “free range” means slightly different things in different parts of the world. Broadly, it means that the animals weren’t confined to a cage and had access to the outdoors. Unfortunately, in the U.S. at least, the animal density can still be very high and the animals may have only short periods outside in an area that’s quite small. Therefore, it is difficult to tell exactly what free range means when you see it on meat packaging in the U.S. You can contact the producer directly for clarification.
• No hormones added – In the U.S. and some other countries where the use of growth hormones is permitted, this term indicates that animals are raised without the use of any added growth hormones. For beef and dairy products it can be helpful, but by law, poultry and pigs cannot be given hormones, so don’t pay extra for chicken or pork products that use this label.

What does "Certified Organic" mean in the U.S.?

Keep in mind that even if a producer is certified organic in the U.S., the use of the USDA Organic label is voluntary. At the same time, not everyone goes through the rigorous process of becoming certified, especially smaller farming operations. When shopping at a farmers’ market, for example, don’t hesitate to ask the vendors how their food was grown.

Source: Organic.org

Tips for keeping the cost of organic food within your budget

Organic food is often more expensive than conventionally grown food. But if you set some priorities, it may be possible to purchase organic food and stay within your food budget. Purchase the organic versions of the foods you eat the most and those that are highest in pesticides if conventionally grown.

Venture beyond the grocery store. Consider the following ideas for finding organic food:

• Shop at farmers' markets. Many cities, as well as small towns, host a weekly farmers' market, where local farmers bring their wares to an open-air street market and sell fresh produce direct to you. Often you will find items for less than you'd pay in the grocery store or supermarket. Bonus: it's a great opportunity to socialize and get to know like-minded people in your neighborhood who might want to join a Community Supported Agriculture (CSA) farm or start a buying club with you.
• Join a food co-op. Find out whether there is a natural foods co-op, also called a cooperative grocery store, in your area. Co-ops typically offer lower prices to members, who pay an annual fee to belong. However, you do not need to be a member to shop at a food co-op.
• Join a Community Supported Agriculture (CSA) farm, in which individuals and families join up to purchase "shares" of produce in bulk, directly from a local farm. Local and organic!

Organic food buying tips

• Buy in season – Fruits and vegetables are cheapest and freshest when they are in season. You can also find out when produce is delivered to your market. That way you know you're buying the freshest food possible.
• Shop around – Compare the price of organic items at the grocery store, the farmer’s market and any other venue (even the freezer aisle!). Purchase the most economical ones.
• Remember that organic doesn’t always equal healthy – Junk food can just as easily be made using organic ingredients. Making junk food sound healthy is a common marketing ploy in the food industry but organic baked goods, desserts, and snacks are usually still very high in sugar, salt, fat, or calories.

Why is organic food often more expensive?

Organic food is more labor intensive since the farmers do not use pesticides, chemical fertilizers, or drugs. Organic certification and maintaining this status is expensive. Organic feed for animals can cost twice as much. Organic farms tend to be smaller than conventional farms, which means fixed costs and overhead must be distributed across smaller produce volumes. Most organic farms are too small to receive government subsidies.

Enjoying the benefit of fish without harmful side effects

There is a lot of confusion surrounding the healthfulness of seafood. Fish is low in saturated fat and can be a good source of high-quality protein, omega-3 fatty acids, and other essential nutrients. Yet common toxins such as mercury are also found in fish. What does this mean? How much is okay? Which fish are safe?

Each year dangerous quantities of mercury are emitted into the air (an aspect of widespread industrial pollution). When it rains, this pollution goes into our lakes and oceans where it contaminates the fish and shellfish that live there. Seafood can contain harmful chemicals such as mercury, PCBs, chlordane, dioxins, and DDT. This is a problem because eating fish contaminated with mercury, a poison that interferes with the brain and nervous system, can cause serious health problems. The top predators, such as sharks, contain the highest levels of these contaminants. Nursing mothers, pregnant women, women who may become pregnant, and young children have the highest risk, so are advised to avoid all large fish (shark, swordfish, king mackerel, tilefish, etc.).

In recent years there has been a huge decline in many species of fish, caused by unsustainable fishing and farming practices. This means that if changes are not made soon, many wild populations of fish may become extinct.

Sustainable seafood choices

Seafood can be part of a healthy diet if you know what type of fish to choose. There are a number of smartphone apps and downloadable wallet-cards for you to keep on hand to use in the grocery store or a restaurant. These guides are updated often and contain the latest information on healthful and sustainable seafood choices. Find links in the Resources section below.

Source: HelpGuide

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Hydroponics for Home Gardeners

By: J. Raymond Kessler Jr., Extension Specialist, Associate Professor; J. David Williams, Department Head and former Extension Specialist; and Robyn Howe, Undergraduate Student, all in Horticulture, Auburn University

For centuries, civilizations throughout the world have experimented with soilless gardening, from the ancient Babylonians to the Aztec Indians. Marco Polo spoke of China’s magnificent floating gardens, and there is documentation that the Egyptians practiced primitive hydroponics. It was not until the 1930s, however, that this “new” form of gardening began to receive notice due to the notable experimentation of Dr. W.E. Gericke of the University of California. Gericke, often called the “father of modern hydroponics,” coined the term hydroponics, which literally means “working with water.” Since that time, many developments have been made, and hydroponic gardening continues to grow and thrive in popularity and usage.

Hydroponics is, simply put, growing plants without soil. The discovery was made years ago that it was not the actual soil that plants need to grow is the mineral nutrients held by soil particles or those unleashed through the action of bacteria and worms. The nutrients slowly dissolve in the surrounding soil-water solution, and the roots then absorb the nutrients from the soil-water. All plants have the same basic needs whether they are grown in soil or not. When the plant’s nutritional needs are met, soil is no longer necessary. In fact, the soil may harbor pathogens and other organisms that could harm the plant. In hydroponics, all the nutrients are supplied in a water solution that passes over the roots or floods around them at regular intervals. Plants often grow faster in a hydroponic system because nutrients are immediately available and therefore can be assimilated faster.

When experimenting with hydroponics, as with all other gardening techniques, it is important that the gardener know the basic physiology of the plant that is, how the plant works. Plants use their roots to draw in water and minerals that are trans-ported upward into the leaves. They also take in oxygen and release carbon dioxide in respiration.

The leaves absorb energy during the day from sun-light and take up carbon dioxide from the air. The water from the roots, the carbon dioxide, and the light energy combine to form carbohydrates such as sugar. The plant then releases oxygen back into the atmosphere. These actions, aided by the nutrients gleaned from absorbed minerals, complete the process of photosynthesis, providing the energy and raw materials for growth. At night, the process reverses in the leaves. Carbohydrates break down, releasing the energy needed to create new leaves, stems, and roots, and carbon dioxide is released.

Plants, much like human beings and animals, re-quire water, air, food, light, and warmth in order to perform these essential physiological processes and, as a result, to grow and reproduce. The basic hydroponic system should fill the needs of the plant’s roots just as the earth would by providing support, oxygen and carbon dioxide exchange (via the substrate), and water and nutrients (via the nutrient solution). Adequate light and warmth complete the minimal requirements for successful hydroponic plant growth.

Substrate

In order to serve as a suitable replacement for soil, the substrate must be capable of supporting the root system and holding moisture and nutrients. It should be inert, free of insects and diseases, and not easily broken down. Also, the substrate should allow adequate aeration of the roots and have good drainage qualities. Plants need sufficient access to oxygen in the air in order to grow and take up water and nutrients. Poor drainage can lead to de-creased growth, stunting, wilting, and discoloration of the leaves and, in the worst cases, “drowning.”

Several commonly used substrates are coarse sand (ask for washed river sand), gravel, perlite, coarse vermiculite, and rock wool. Perlite and coarse vermiculite are good choices because they are sterile, uniform, and readily available in garden centers. Sand and gravel also work well but should be washed thoroughly before planting to remove lime or other impurities.

Water

Mature plants process a surprisingly large amount of water. For instance, a fully grown to mato plant may use up to 2⁄3gallon of water a day. An inadequate water supply is the most limiting factor to plant growth. Water deficiencies can cause the plant to spend all its available energy on developing an extensive root system, the result being a small, stunted shoot. For this reason, it is important that the media be flooded, and subsequently drained, one to three times daily or as often as necessary to keep the roots moist.

Light

The amount of light required varies from plant to plant. Most fruiting plants such as corn, tomatoes, and peppers need 8 to 10 hours of sunlight a day. If these plants are grown indoors, an artificial light must be used to provide high light intensity without causing the temperature to rise above acceptable levels. This situation may be difficult to achieve. On the other hand, many ornamental and foliage plants require less sunlight than fruiting plants do and therefore perform very well indoors. One common error in applying hydroponics is trying to grow plants in reduced light when full sun is required.

Temperature

Warm-season plants perform best when the temperature is between 70 and 80 degrees F during the day and 60 to 70 degrees F at night. Cool-season plants generally require temperatures approximately 10 degrees lower than those suitable for warm-season plants. Above or below this range, plant growth will slow dramatically. Therefore, it is important that these temperatures be maintained whenever possible.

Nutrients

The key ingredient in the recipe for successful hydroponic gardening is the nutrient solution. In traditional soil-based gardening, the plant receives fertilizer from the slow breakdown of organic materials and the release of mineral nutrients in the soil. Hydroponic systems provide readily available, water-soluble minerals directly to the roots in a complete and balanced solution, thus eliminating the need for soil.

There are sixteen elements needed for plant growth. Plants extract several of these elements, such as oxygen, carbon, and hydrogen, from water and air. The rest of the elements must be supplied through the nutrient solution.

The primary macronutrients are nitrogen (N), phosphorus (P), and potassium (K). The secondary macro-nutrients are calcium (Ca), magnesium (Mg), and sulfur (S). These distinctions are made based on how much of each nutrient plants need. Micronutrients, or trace elements, such as iron (Fe), manganese (Mn), boron (B), molybdenum (Mo), zinc (Zn), copper (Cu), and chlorine (Cl) are used in very small amounts by plants, hence the name micronutrients. Micronutrients are sometimes present as impurities in the water and in the solid substrate.

Nitrogen

Nitrogen is central to the development of new leaves and stems as well as to overall growth and performance. An overabundance of nitrogen causes soft, weak growth and possible delay of fruit and flower production. Symptoms of nitrogen deficiency are yellowing leaves and weak, spindly growth.

Phosphorus

Phosphorus is used by the plant in photosynthesis and in the production of flowers and seeds. It also encourages strong root growth. When phosphorus levels are low, the older leaves begin to turn deep green and develop brown or purple dis-coloration. Other symptoms may be stunted growth and chlorosis, or yellowing, of the lower leaves.

Potassium

Potassium is necessary during all stages of growth, particularly during fruit development. It is involved in the manufacture of sugars, starches, and chlorophyll. Potassium helps the plant make good use of air and water by regulating stomatal openings in the leaves and also helps build strong roots. Deficiency symptoms are mottling and yellowing of older leaves, generally along the margins, and flower and fruit drop.

Calcium

Calcium is used by the plant in the manufacture and growth of cells. It also acts as a buffer for excess nutrients in soil. Calcium deficiency is recognizable by the curling and stunting of young leaves and dieback of the shoot tip. Too much calcium can stunt the growth of a young plant.

Magnesium

Magnesium is fundamental in the absorption of light energy and is central to the structure of the chlorophyll molecule. Symptoms of magnesium deficiency include curled leaf margins, yellowing of older leaves (veins remain green), and, eventually, bright green coloration of the growing tips.

Nutrient Solutions

The elements needed for successful hydroponic growth are widely available in premixed form from gardening catalogs, garden centers, fertilizer companies, and hydroponic supply companies. Most hydroponics amateurs will rely on these commercially available mixes rather than preparing their own solutions at home.

However, for those enthusiasts who are willing to mix their own, the extra time and effort may offer more precise nutrient combinations for specific plants, as well as provide an opportunity for experimentation. Many nutrient solution recipes have been developed, some for general use and others for specific plants, and no one recipe is better for all plants than another. Hydroponic nutrient solutions contain several water-soluble, nutritive salts that can be purchased at fertilizer companies, green-house supply companies, and chemical companies.

The primary and secondary macronutrient salts are usually mixed in a large volume of water at a concentration ready to use on plants. The micronutrients are mixed as separate concentrated solutions that are then added in a measured amount to the macronutrient solution.

To make your own solution, mix 10 gallons of macronutrient solution according to the recipe in either Table 1 or Table 2. Nutrient solution No. 1 is more appropriate for slow-growing plants and plants growing under low light intensity, such as foliage plants. Nutrient solution No. 2 is more appropriate for rapidly growing plants and plants under high light intensity, especially vegetables. Next, mix the following two micronutrient solutions, and add each to the macronutrient solution.

• Mix 7.6 grams (11⁄4level teaspoons) of boric acid (H3BO4) and 0.6 grams (1⁄10teaspoon) of manganese chloride (MnCl2• 4H2O) in 1 quart of water.

Use 1⁄2cup of this solution for 10 gallons of macro-nutrient solution.

• Mix 3 grams (1⁄2level teaspoon) of chelated iron (NaFe EDTA) in 1 quart of water. Use 1 3⁄5cup of this solution for 10 gallons of macronutrient solution.

After mixing the nutrient solutions together, check the pH. (Meters for measuring pH can be purchased from garden and hydroponic supply companies.) Most plants grow well in a slightly acidic solution with a pH of 5.5 to 6.5. If the solution is too alkaline (pH greater than 7.0), add a few drops of white vinegar per gallon, stir, and recheck the pH. If the solution is to acidic, add a small amount of baking soda per gallon to increase the pH. Continue rechecking and making adjustments until the desired pH level is reached.

The nutrient solution can be reused for 10 to 14 days when applied one to three times a day. At the end of this period, flood the substrate with clean water and drain it several times to wash out any accumulated materials. Mix and add a new solution.

Simple Hydroponic Systems

The simplest hydroponic system for beginners is a non recycling system consisting of a well-drained container filled with an acceptable A larger-scale version of the recycling method involves using a container that has a hose and an outlet an inch or two from its base. The container must be raised off the floor and tilted so that the nutrient solution drains through the outlet into a receptacle. These simple hand-fed methods work best with small-scale systems. For larger systems, a submersible pump can be used to pump the solution back into the container from the receptacle substrate. The nutrient solution is mixed, and then it is applied one to three times daily, using a simple watering can. The excess solution drains away and is lost.

A more economical technique is the recycling method, which involves collecting and reusing excess solution. The simplest version of this technique involves placing a large dish under the plant container to catch the solution and then pouring the solution back over the plant at regular intervals.

In addition to the systems that require a substrate, there are non aggregate methods such as water culture and aeroponics. In water culture, the plant’s roots are kept submerged in the nutrient solution. The plants are supported by a grid of wire, rope, or string or by coarse screening. This method, however, introduces aeration problems and re-quires an aquarium pump to bubble oxygen into the nutrient solution.

One simple version of water culture for a single plant consists of using a pint- to quart-sized glass or plastic bottle or jar that has a stopper or lid with two holes in it. The stem of a young plant is passed through one hole so that the plant is held above the nutrient solution and the roots are in the nutrient solution. The plant’s stem is surrounded with cotton for support. The nutrient solution is aerated by an aquarium pump. The plastic tube from the pump is passed through the second hole in the lid and into the nutrient solution. The container is covered with aluminum foil to keep light off the root system.

In aeroponics, the plant’s roots are suspended in air and are regularly misted with a fine spray of nutrient solution. Misting must occur often enough to cover the roots with a constant film of nutrient solution at all times. The misting chamber must be kept dark so algae does not grow and compete with the roots. This method requires more mechanical and electrical sophistication than the previous methods do. The methods that use a substrate are generally less expensive, are easier to transplant from, and have fewer difficulties than the water or aeroponics methods do.

Getting Started

It is important that the beginner keep in mind that hydroponics is not the perfect solution to all gardening woes. There are pros and cons to both traditional soil-based gardening and hydroponics. One major disadvantage of hydroponics is the commitment of time and energy necessary for success. Soilless gardening is much more exacting than traditional gardening and may overwhelm the novice gardener if too complex a system is implemented.

Begin with a small project such as an herb garden to get a feel for hydroponics, and, as your knowledge and comfort increase, move on to a more elaborate system.

^{Source: Alabama Cooperative Extension System}

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Cultural Methods of Vegetable Disease Control

Most vegetables are susceptible to one or more diseases. You can, therefore, anticipate disease problems sooner or later in your vegetable garden. By following good cultural practices and taking preventive measures, your chances of garden failure due to disease problems can be reduced.

Garden site selection is important to pro-duce high yields of healthy vegetables. Trying to grow vegetables on a poor site is one of the main causes of garden failure. Although few people will have ideal garden sites, they should select the best site available.

Garden sites should not be within the drip line of large trees. Avoid planting near black walnut trees, since they produce a root sub-stance that is toxic to certain vegetables, especially tomatoes. The garden site should be slightly sloped to provide good water and air drainage through the soil.

Excess soil moisture can damage vegetable roots, as well as promote root diseases caused by certain fungi. Air movement through the garden is also important to help dry the foliage, thus reducing the chances of fungal and bacterial infections. Garden sites with good air drainage are less likely to be damaged by late frosts.

Most garden vegetables require full sunlight for maximum production. Sunlight also hastens drying of foliage. Soil tillage should be done early enough, prior to planting, to allow decomposition of raw organic matter such as manure or green plant material. This usually requires about six weeks under warm temperatures and longer at low temperatures. Organic material that has not decomposed can be a source of disease organisms and can also promote development of certain diseases such as root and stem rots. Applying nitrogen fertilizer before plowing or tilling green plant material into the soil will hasten its de-composition.

Crop rotation will help prevent the buildup of disease-causing organisms in the soil. Some disease causing organisms affect one vegetable or group of vegetables, but may not affect an-other. Several vegetables of the same family, such as squash, cucumbers and cantaloupes, may be affected by the same disease. Therefore, it is not a good practice to grow plants of the same family in rotation. Table 1 gives crop groupings for rotation to control soil-borne diseases. At least a three-year rotation is suggested for vegetable crops.

Sanitation is very important in controlling vegetable diseases. Many disease-causing organ-isms survive the winter in plant debris, cull fruit or plant stubble left in the garden. Any practice that will eliminate these overwintering sites for fungi, bacteria, viruses and nematodes will reduce the occurrence of disease problems the following year. Removal or plowing-under of crop stubble and trash helps destroy overwintering populations of disease organisms. Some disease-causing organisms are able to survive the off season on contaminated equipment or containers. Equipment that has been used in disease-infested vegetable gardens or containers used in handling diseased vegetables should be disinfested before being used again.

Disease-free seed and transplants are a must in vegetable production. Seed should not be saved from diseased plants. Always buy seed from a reputable dealer, since you normally cannot tell from their external appearance if seed are contaminated with disease-causing organisms.

Certain geographical areas, such as the arid western states, can produce disease-free seed because of climatic conditions. Seed from these areas should be stipulated in your seed orders. Gardeners starting their crop from transplants should, likewise, insist on disease-free plants.

Seed treatments vary, depending on the crop as well as the disease to be controlled. Some disease-causing organisms are carried on the surface of seed and can be controlled by a simple fungicide treatment. Fungicides are not effective against those organisms carried beneath the seed coat.

Fungicides applied to seed also give young seedlings some protection from soil-borne disease organisms as they germinate and emerge. Such treatments, however, do not control organisms that attack the plant after the seedling stage.

A seed treatment is usually applied by the company from which the seed is purchased. Home-grown seed can be treated at home with relative ease. Thiram or Captan fungicides can be used as seed treatments on most vegetable crops. Use these protectant fungicides according to instructions on the label. For small quantities of seed, such as packets, apply sufficient fungicide to coat the seed surface. Simply place a small quantity (comparable to the size of a match head) in the packet, reclose and shake to coat the seed with the fungicide.

Planting dates can be an effective tool in reducing diseases of vegetables. Okra, for in-stance, requires warm soil for good germination and growth. If planted when the soil is still cold, the seeds will rot, or if they do germinate, they will probably develop damping-off or stem rot. Some crops, such as corn and beans, should be planted as early as the weather permits to escape severe virus infections. Aphids that transmit viruses are usually at lower population levels early in the season.

Mulches can be used to conserve moisture, keep fruit clean and prevent diseases. Mulches reduce fruit rot on crops, such as strawberries, tomatoes, squash, cucumbers and melons by preventing direct contact with the soil. Mulching will reduce splashing of soil onto lower fruit and foliage by rain.

Staking or trellising tomatoes, pole or half runner beans and cucumbers will prevent soil contact with the foliage and fruit. Air circulation will be better if these plants are trellised, thus promoting better drying of foliage and reducing diseases. Pesticides can be more effectively applied to trellised plants.

Watering can influence the development and severity of many foliage diseases. Wet foliage is favorable for the development of most diseases. To reduce infections, apply irrigation water to the soil rather than the foliage. If water must be applied to the foliage, then it should be done in late morning or mid-afternoon to allow the foliage to dry before evening.

Maintaining uniform soil moisture can re-duce problems such as blossom end rot of pe-pers and tomatoes. Excessive soil moisture can result in increased root and stem rot diseases. It is best to work in the garden when the foliage is dry to reduce disease spread. Bacterial diseases of tomatoes, beans and other crops are readily spread on hands and clothing of workers when the foliage is wet.

Use of resistant varieties is one of the most economical ways of controlling vegetable diseases. Resistant varieties should be used in areas where diseases are present or where the soil is known to be infested with disease-causing organisms. Resistant varieties should be used even when rotation is practiced.

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Knowledge and Agriculture

Education, the cornerstone of a knowledge economy, is given a low priority in developing countries. This is because of the vested interests of powerful but corrupt parliamentarians who find it in their interests to keep the masses subjugated and enslaved. Education brings understanding and awareness, and frees the minds to question those in power. Distorted forms of democracy in which there is no accountability of the rulers have been set up in many developing countries. Such democracies only serve a few corrupt leaders who loot and plunder at will.
The attempt in 2010 to destroy the Higher Education Commission (HEC) was the brainchild of some politicians with forged degrees who felt threatened by a high quality, merit-based organisation operating like an oasis in a sea of corruption. It was saved by the intervention of the Supreme Court of Pakistan on an appeal (filed by the Atta-ur-Rahman, Ms Marvi Memon and Azam Swati) that gave a judgment that the attempt to shred the HEC was unconstitutional. Now, however, some evil minds are plotting the death of the HEC again.
With their eyes on the Rs44 billion annual grant of higher education, some “honourable” parliamentarians have recently moved a bill in parliament that will take away the control of the funds from the HEC and give it to a federal ministry. At present the funds are controlled by a 17-member commission that includes the provincial secretaries of education, eminent educationists and respected citizens. India, by contrast, has decided to close down its University Grants Commission and establish an organisation similar to the HEC. The Indian cabinet approved the establishment of the National Commission on Higher Education and Research (NCHR) in December 2011.

HIt is time for the political parties in Pakistan to unite, rise up once again and kill the vile attempt by the corrupt to take control of the Rs44 billion annually made available to the HEC for the operational and development needs of the universities in Pakistan.
By the year 2000 the gap between rich and poor countries had reached 500:1 (World Bank) and it continues to increase with every passing day. While some countries such as Japan, South Korea, Singapore, Taiwan and, more recently, China have managed to narrow this gap between the rich and the poor, most other developing countries, including Pakistan, are lagging far behind. Knowledge and technological innovations are identified as two essential capabilities for bridging this gap. Since no country has all the resources to achieve technological competence in all fields, most countries have concentrated on finding one or two areas of specialisation for comparative advantage. For Pakistan, this advantage at present, according to our study, lies in the agriculture sector.
The agriculture sector in Pakistan supports two-thirds of the rural population and remains the largest income and employment generating sector of the economy but accounts for only 22 percent of the total gross domestic product. Pakistan has not been able to exploit its immense agriculture potential due to under- investment in human resource development and agriculture research. According to the Consultative Group on International Agricultural Research (CGIR), public expenditure for agriculture research in Pakistan as a percentage of agricultural GDP is only 0.29 percent, whereas India and Bangladesh spend 0.36 percent and Mexico and Kenya spend 1.21 percent and 1.30 percent, respectively.
The 15-year agriculture reform and development vision for Pakistan was prepared under the supervision of one of us (Dr Atta-ur-Rahman). It involved research scientists, industrialists, farmers association and economists and identified critical skills, technology, management and public policy gaps in all fields of agriculture including major grain crops, horticulture, fisheries, animal husbandry, rangelands and forestry. Research areas, technological inputs and better operational practices needed in soil, seed, fertilisers, pesticides and water management as well as the transport, grain storage and cold chain infrastructure required for prevention of 40-45 percent of post harvest losses have been identified.
It was observed that 75 percent of Pakistan’s agriculture potential remains untapped. Crop yields on average are lower by 31-75 percent of the productivity level achieved at local research stations and lower by 50 percent to 83 percent in developed countries. These productivity gaps can be addressed through increased inputs in human resource development, research, technology and extension services and through improved management of resources and inputs. Improved access to institutional credit and access to local and international markets are essential prerequisites. Pakistan has all the basic ingredients to excel and eventually lead in agricultural innovation at regional level.
Most of the agriculture research organisations. however, are poorly managed and remain ill-equipped with modern machinery, library and information infrastructure and qualified staff. There are no incentives for scientists to innovate and there are weak linkages between stakeholders (i.e., researcher, farmers, entrepreneurs and policymakers) due to a weak extension services system. In order to carry out reforms of the system and to increase agriculture productivity an investment of Rs1078 billion will be required over a period of 15 years. This investment is expected to generate Rs2,368 billion as net benefits with an internal rate of return close to 108 percent (PIDE 2003).
At their initial stages of development most developed countries invested in agriculture innovations to eliminate rural poverty and to bridge the income inequality gap between rural and urban populations in their societies. China’s agriculture reform programme has not only lifted millions out of poverty but generated enough income for investment in industrial innovations. The successful programme, which began in the early 1980s, is premised on providing flexible, demand-driven packages of services, not just technology but also information, technical assistance, marketing and developing supply networks and supply chains.
In 1986, the Chinese ministry of science and technology initiated the nationwide “Spark” Programme (derived from the Chinese proverb “A single spark can start a prairie fire,” meaning that the spark of science and technology will spread over vast rural areas of China). Its overall objectives were to help transfer managerial and technological knowledge from more advanced sectors to rural enterprises and to help increase productivity and employment.
We need to learn how countries such as China, Egypt and India have modernised agriculture and are using it to tackle poverty and transition to a knowledge economy. Simultaneously we must resist continuing attempts by crooked minds to destroy the HEC.
Acknowledgement: We are grateful to Bilal Mirza, PhD Fellow, United Nations University-MERIT, the Netherlands, for his valuable input
Prof. Atta-ur-Rahman is former federal minister for science an technology and former chairman of the Higher Education Commission
Dr S T K Naim is an expert on STI policy and a consultant at COMSTECH, Islamabad.
Courtesy: The NEWS

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Challenges to Biotechnology in Pakistan

By  Sayyar Khan Kazi

We are living in an age, where almost all aspects of human life have been revolutionized by the highly sophisticated and advanced technologies.  In recent years, we have witnessed on print and electronic media, several scientific endeavors to target innovations and discoveries beyond the boundaries of our planet Earth. Technologically advanced countries such as the USA, European Union, Japan and emerging powers like China and India are beating one another to have speedy access to the mysteries of other planets.

In the quest of unraveling scientific mysteries, several missions from these countries have been launched to Moon, Mars and other planets in order to lead and dictate the terms upon which the human future will rely. Overall, there has been unpreced- ented progress towards industrialization that revolutionized every aspect of human life including medical and health care, aviation, urbanization, infrastructure and agriculture. 

This off course presents a bright picture of the evolution of human civilizations as a result of thousands years of transformation from living in an age of stone to highly civilized societies equipped with social and scientific tools to govern this planet Earth.

Like other scientific disciplines, Agriculture science has received much importance due to the growing needs of expanding populations for more food, feed, fiber and alternative energy resources. In this connection, the advent of modern biotechnology and genetic engineering tools has enabled scientists to manipulate the genetic material of organisms in order to exploit its hidden enormous potential.

In the past two decades, biotechnological tools have brought a paradigm shift in the orthodox and traditional ways and means of improving our various industries, health sciences, environment and agriculture.

For example, in agriculture, since 1995, there has been a sudden boom in the production of transgenic varieties of agricultural crops with enhanced protection from insect pests and diseases. Farmers around the world have gained maximum economic gains from the adoption of these improved crop varieties.

The wide adoption of these improved crop varieties by farmers around the world has resulted a huge economic benefit and positive effects on the environment by less pesticide application.

After the successful production and adoption of disease resistant crop plants, agriculture biotechnology is entering into a new phase of developing second generation transgenic crops that will be able to grow on marginal lands with high water and soil salinity and drought stresses.

It is anticipated that the development of these crop varieties will help to feed the growing populations, particularly in regions of Sub-Saharan Africa and Asia, where majority people are facing hunger, poor quality and malnourished food.

Keeping in view the promising role of biotechnology for securing the future of our coming generations, increasing number of countries, public, private sectors and multinational companies have joined the race and invested billions of dollars for research and development activities.

In some areas, scientists have excelled and accomplished significant targets like crop disease resistance as mentioned above and development of accurate laboratory tools for genetic dissection, diagnosis and research on human genetic diseases.

Pakistan, a developing country is facing multi-faceted challenges including energy crisis, food security, rapid urbanization and declining fresh water resources in the wake of increasing population and the more global phenomenon of climate change.

Like other countries, Pakistan also took a bold step towards adoption of modern biotechnology and started to establish biotechnology centers across the country. In all key national science and technology policies, the role of biotechnology as a potential tool for the growth and socio-economic development has been well acknowledged.

In National science and technology policies launched in 1997 and later in 2009, biotechnology was emphasized one of the priority areas. Pakistan also contributed and pioneered the establishment of an International Center for Genetic Engineering and Biotechnology (ICGEB), initially proposed to be built in Pakistan but later on jointly built in India and Italy.

Despite the initial recognition and quick response, biotechnology did not take roots as an emerging source of socio-economic development in the country. For example, we started research on insect resistant transgenic cotton varieties back in 1995 and developed some transgenic lines but it took almost 15 years to launch legal commercial cultivation of these varieties in 2010.

The other leading cotton producing countries namely USA, China and India adopted and commercialized transgenic cotton varieties in 1996, 1997 and 2002 respectively and farmers in these countries earned huge economic gains.

In addition, we are also lagging behind other countries in development of second generation transgenic crops with improved tolerance to environmental stresses and crops for bio-energy production. The dependency on fossil fuels as energy sources is on the decline because of the enormous potential of bio-feed stocks (crops, trees and grasses) to produce bio-energy products such as ethanol, biodiesel, butanol and petroleum on industrial scale.
Source: The Frontier Post

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Ban imposed on release of inland subsidy on sugar export

MUSHTAQ GHUMMAN

Caretaker Minister for Commerce and Textile Industry, Maqbool H H Rehmatoola has reportedly imposed a ban on release of inland subsidy on export of sugar as well as the subsidy under the Strategic Trade Policy Framework (STPF) 2009-12 and 2012-15, well informed sources told Business Recorder.

The Economic Co-ordination Committee (ECC) of the Cabinet, under the three-week long leadership of former Finance Minister, Saleem Mandviwalla, approved billions of rupees of financial incentives for politically influential sugar industry under the guise of inland subsidy on a summary moved by the Commerce Ministry.

However, the decision, considered questionable could not be implemented; several decisions taken by Saleem Mandviwalla are currently being heard by the Supreme Court of Pakistan. "Commerce Minister believes that the amount of inland subsidy can be used in elections, which is why he imposed a ban on the release of the amount under this head," the sources added.

Likewise, processing of cases of release of subsidy to exporters as announced in STFP is to be discontinued by the Trade Development Authority of Pakistan (TDAP). The Minister feels that TDAP should not release any amount under that head as it would be considered against the directives of Election Commission of Pakistan. The officials in TDAP and Trading Corporation of Pakistan (TCP), who intended to expedite cases of sugar mill owners and exporters for release of subsides were likely to be disappointed with that decision, said an official on condition of anonymity.

The sources said ECC in its meeting on March 6, had approved inland subsidy of Rs 1.75 per kg on 1.2 million tons of sugar. Earlier, the ECC meeting presided over by former finance minister Abdul Hafeez Shaikh had approved Rs 8 billion incentives on export of 1.2 million tons of sugar on summaries prepared by the Commerce Ministry and the Federal Board of Revenue (FBR).

However, SRO issued by the FBR favoured only sugar mills of Sindh zone. According to sources, Punjab produces 60 percent and KP 10 percent of overall sugar output in the country. The exclusion of both provinces has been strongly lamented by the industry as the SRO only favours one province. This SRO is being challenged in the court as discriminatory in nature and the major quantum of growers'' payments relates to Punjab. If KP and Punjab mills try to export through Karachi Port for destinations other than Afghanistan and CIS, it costs over 20 dollars in terms of haulage and it is practically impossible to export. According to sources, Secretary Finance Dr Waqar Masood has decided that the issue of release of inland subsidy should be left to the new elected government.

^{Source Business Recorder}

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Dry seeded rice technology

By Zuhair Hasnain

Dry seed rice cultivation on the mechanical lines is the linkage of past practice with throughput technology, becoming indispensable to address problems like drudgery, high production cost, low quality, low crop intensity and above all water and labour scarcity.
The sowing of dry seeds into dry or moist, non-puddled soil has many advantages over traditional transplanting and is a principal method of rice growing in many parts of the world including Philippines, Vietnam, Thailand, Korea, America, Japan and the sub-Saharan Africa.
In Pakistan traditional dry seeding in rice is reported only in few acres across Punjab and a big space exist for both research and extension wing of the agriculture department for its standardisation, popularisation and adaptation. With the recent developments in rice production technology across the globe, there should be flexibility in opting for the prevailing patterns and latest trends to achieve self-sufficiency and resource conservation.
Dry seeded rice, a simple approach, is beneficial for farmer. The foremost principal underlying this theory is water saving, cost benefit ratio, efficient land utilisation and better management practices. Water situation in the country and its scarcity need not be elaborated. In dry seeding of rice 30 per cent of water can be saved by eliminating puddling and if
intermittent irrigation (alternate wetting and drying concept), a new method of irrigation, is used additional 15-30 per cent of water can be saved and that can be a big achievement.

Beside, about 40 per cent of labour cost can be saved by dry seeding method. Dry seeding also implies time saving, quicker land preparation in effective manner, and maximised yield.
Going ahead, if one more step is taken by clubbing the dry seeding rice cultivation with mechanised farming, it can reward the farmers more by generating the idea of intensification, higher yield with low input, reduced tillage and efficient utilisation of nutrients (proper placement and time).
Mechanisation will lead the growers to resource use efficiency and sustainable agriculture while muting the voice of environmental pollution.
The biggest challenge to this practice is weed manifestation. Various pre- and post-emergence chemicals have been introduced to fix it. Besides this, research is going worldwide over this system of cultivation for best management practices under innovative ideas by agronomists in regards to response of new breeding lines, adaptation to different soils and climatic conditions, and effective use of mechanisation concept.
Finally, this change in sowing pattern is expected to have a big impact on Asian rice production efforts and on the region’s economies. This is because one of the main forces driving such changes has been shrinking resources in the region, especially available land and water.
Pakistan should be a part of knowledge sharing and applied research centers working round the world. This way one can succeed in the achievement of mutually agreed benefits such as serving humanity, coping food security and fighting for the cause of hunger.
Effort in the direction of increasing output at the least cost is more important as the world population is going to increase to nine billion by 2050, which will require more than doubling the current food production. Asia grows 90 per cent of rice of the world which is mostly consumed by its population.
Each hectare of rice-producing land at present is providing food for 27 people. By 2050, because of growth in population and increasing urbanisation, each hectare will have to feed at least 43 people. This means that yields must be enhanced by at least 50 per cent over the next 40 years to prevent mass malnutrition among the 700 million Asians.
The writer is a PhD research scholar at The International Rice Research Institute, Los Banos, Philippines.

z.hasnain@irri.org

Courtesy: The DAWN

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Agriculture: Soil Microbiology

Soil Microbiology Until fairly recently, the living soil has been considered as a functional black box that is intrinsically too difficult to be unravelled into its core components. However, this concept has changed with the advent of the modern methodologies. The intricacies of microbial life in soil has been impacted by the advanced, mainly molecular-based, approaches that have been unleashed on the soil habitat in recent years.

The application of molecular and other advanced methods (cultivation-independent analyses) has provided exciting new insights into microbial life in soil. Soil is an extremely diverse and complex habitat containing many microsites and gradients that form a range of different biogeochemical interfaces. Depending on the proportion of sand, silt and clay, the surface area in soil can vary from 11 cm2 up to 8 million cm2 per gram of soil read more.

The aggregates formed by minerals, soil organic matter, fungal hyphae, roots and plant debris offer a range of potential niches for microorganisms with different lifestyles. The architecture of the soil pore network essentially defines the habitat colonized by the microorganisms and the pore space strongly influences the nature and extent of the interactions between the organisms inhabiting the soil. The latest news, research, and developments in energy technology from the technology Truenergy melbourne Save water. Save Energy. Save Money. Ecovantage improves the sustainability of your home and your budget.

The heterogeneous physical structure of soil affects the spatial distribution of water, oxygen and nutrients, which in turn influences the composition and activity of the microbial communities themselves. As an example, the spatial distribution of bacteria in topsoil and subsoil was found to be different, but lateral variations in spatial distributions are also likely to occur. Soil is the surface layer of earth on which the human civilization depends for its existence. Actually soil represents the loose upper crust of the earth surface distinctly different from the underlying bed rock.

Its depth, colour, composition vary from place to place, but all soils are common in consisting of inorganic (mineral) and organic matter, water, and gaseous phases. Every soil is made up of a succession of layers, collectively known as soil-profile, reaching down to the parent material. The soil-profile consists of two or more horizontal layers, called horizons. The soil horizon may vary in thickness, mineral composition, and structure; they are indicated by the letter A1, A2, A3, B1, B2, B3, C1, etc. A1 horizon is the uppermost or surface layer of the soil and its fertility level is very important from viewpoint of an agriculturist.

Soil fertility depends not only on the presence of inorganic and organic substances, but also on the

presence of various species of

Courtesy:Restoration Soil

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Role of Potassium in Crop Yield

Potassium is vital to many plant processes. A review of its role involves under-standing the basic biochemical and physiological systems of plants. While K does not become a part of the chemical structure of plants, it plays many important regulatory roles in development.

Enzyme Activation

Enzymes serve as catalysts for chemical reactions, being utilized but not consumed in the process. They bring together other molecules in such a way that the chemical reaction can take place.

Potassium “activates” at least 60 different enzymes involved in plant growth. The K changes the physical shape of the enzyme molecule, exposing the appropriate chemically active sites for reaction. Potassium also neutralizes various organic anions and other compounds within the plant, helping to stabilize pH between 7 and 8...optimum for most enzyme reactions.

The amount of K present in the cell deter-mines how many of the enzymes can be activated and the rates at which chemical reactions can proceed. Thus, the rate of a given reaction is controlled by the rate at which K enters the cell.

Stomatal Activity (Water Use)

Plants depend upon K to regulate the opening and closing of stomates...the pores through which leaves exchange carbon diox-ide (CO 2), water vapor, and oxygen (O2) with the atmosphere. Proper functioning of stomates is essential for photosynthesis, water and nutrient transport, and plant cooling. When K moves into the guard cells around the stomates, the cells accumulate water and swell, causing the pores to open and allowing gases to move freely in and out.

When water supply is short, K is pumped out of the guard cells. The pores close tightly to prevent loss of water and minimize drought stress to the plant. If K supply is inadequate, the stomates become sluggish – slow to respond – and water vapor is lost. Closure may take hours rather than minutes and is incomplete. As a result, plants with an insufficient supply of K are much more susceptible to water stress.

Accumulation of K in plant roots produces a gradient of osmotic pressure that draws water into the roots. Plants deficient in K are thus less able to absorb water and are more subject to stress when water is in short supply.

Photosynthesis

The role of K in photosynthesis is complex. The activation of enzymes by K and its involvement in adenosine triphosphate (ATP) production is probably more important in regulating the rate of photosynthesis than is the role of K in stomatal activity.

When the sun’s energy is used to combine CO2and water to form sugars, the initial high-energy product is ATP. The ATP is then used as the energy source for many other chemical reactions. The electrical charge bal-ance at the site of ATP production is maintained with K ions. When plants are K deficient, the rate of photosynthesis and the rate of ATP production are reduced, and all of the processes dependent on ATP are slowed down. Conversely, plant respiration increases which also contributes to slower growth and development.

In some plants, leaf blades re-orient toward light sources to increase light interception or away to avoid damage by excess light, in effect assisting to regulate the rate of photosynthesis. These movements of leaves are brought about by reversible changes in turgor pressure through movement of K into and out of specialized tissues similar to that described above for stomata.

Transport of Sugars

Sugars produced in photo-synthesis must be transported through the phloem to other parts of the plant for utilization and storage. The plant’s transport system uses energy in the form of ATP. If K is inadequate, less ATP is available, and the transport system breaks down. This causes photosynthates to build up in the leaves, and the rate of photosynthesis is reduced. Normal development of energy storage organs, such as grain, is retarded as a result. An adequate supply of K helps to keep all of these processes and transportation systems functioning normally.

Water and Nutrient Transport

Potassium also plays a major role in the transport of water and nutrients throughout the plant in the xylem. When K supply is reduced, translocation of nitrates, phosphates, calcium (Ca), magnesium (Mg), and amino acids is de-pressed. As with phloem transport systems, the role of K in xylem transport is often in con-junction with specific enzymes and plant growth hormones. An ample supply of K is essential to efficient operation of these systems.

Protein Synthesis

Potassium is required for every major step of protein synthesis. The “reading” of the genetic code in plant cells to produce proteins and enzymes that regulate all growth processes would be impossible without adequate K. When plants are deficient in K, proteins are not synthesized despite an abundance of avail-able nitrogen (N). Instead, protein “raw materials” (precursors) such as amino acids, amides and nitrate accumulate. The enzyme nitrate reductase catalyzes the formation of proteins, and K is likely responsible for its activation and synthesis.

Starch Synthesis

The enzyme responsible for synthesis of starch (starch synthetase) is activated by K. Thus, with inadequate K, the level of starch declines while soluble carbohydrates and N compounds accumulate. Photosynthetic activity also affects the rate of sugar formation for ultimate starch production. Under high K levels, starch is efficiently moved from sites of production to storage organs.

Crop Quality

Potassium plays significant roles in enhancing crop quality. High levels of avail-able K improve the physical quality, disease resistance, and shelf life of fruits and vegetables used for human consumption and the feeding value of grain and forage crops. Fiber quality of cotton is improved. Quality can also be affected in the field before harvesting such as when K reduces lodging of grains or enhances winter hardiness of many crops. The effects of K deficiency can cause reduced yield potential and quality long before visible symptoms appear. This “hidden hunger” robs profits from the farmer who fails to keep soil K levels in the range high enough to supply adequate K at all times during the growing season. Even short periods of deficiency, especially during critical developmental stages, can cause serious losses.

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