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Organic Farming/Gardening Practice

Achieve Fertile, Balanced & Healthy Soil

Understand how soil affects the growth of crops and plants

 

Contents

Introduction
 
The solid part of the soil
 
Space for air and water
 
The soil community
 
Life in the root zone
 
Bacteria
 
Anion nutrients
 
Cation nutrients
 
Fungi
 
Connecting plants and crops to soil
 
Soil ph and fertility
 
Balancing nutrients

 

 

INTRODUCTION

In the times before the agricultural revolution, people lived by collecting what grew naturally where they were; there was no need to worry about replenishing soil fertility.

Until the nineteenth century, Justus von Liebig (a German contemporary of Darwin)demonstrated that the three "major nutrients" - nitrogen, phosphorus, and potassium - are of prime importance to plant and crop growth. These elements in chemically purified form are added to soil; rapid growth and high yields result. Justus von Liebig is credited with ushering in the age of 'scientific agriculture."

But now, due to scientific agriculture there is overwhelming evidence that there are too many unforeseen and ecologically destructive consequences to this worldview.

Criticism of the increasing industrialization of our food system often focuses on the alarming statistics that show widespread soil degradation. The harm resulting from modern, chemical-intensive soil management methods includes:

Increased soil erosion. This is largely caused by economic factors which discourage conservation measures such as terracing, cover cropping, and windbreaks.

Widespread pollution of surface and groundwater. Water pollution due to fertilizer nitrates and phosphates as well as pesticides and herbicides is becoming a real problem, especially in agricultural areas.

Loss of large areas of farmland from production. Many acres of land are no longer suitable for agriculture due to salt buildup resulting from irrigation practices.

Increased soil compaction, loss of tilth and reduced biological activity. Use of heavy equipment and chemicals that kill earthworms and other soil organisms cause these problems.

Overuse of synthetic fertilizers and pesticides. In many cases, the excessive use of energy-intensive petroleum-based fertilizers and pesticides has destroyed the biological fertility of the soil, so growers use ever-larger amounts of these materials to sustain crop growth.

Organic farming practices are more than simply a return to the old ways, because they are Concerned not only with current soil health and food supply but also with the future of these concerns.

Scientists have steadily accumulated evidence that the pest and disease resistance of plants, that is their ability to resist attack of pests and diseases, is strongly related to the fertility of the soil in which they grow, with the soil's humus content being of primary importance. Studies have demonstrated improvements in the health of animals whose feed was grown on biologically active soil free from chemical fertilizers. In comparisons between potatoes grown organically and those grown using artificial fertilizers, the organically grown produce has consistently shown superior storage qualities, Organically grown grains generally gave a higher content of dry matter, which improves their storage ability and nutrition.

"Feed the soil, not the plant" is fundamental to organic soil management but standard fertilizer recommendations are based only on plant responses to the fertilizers. They fail to consider such things as effects on earthworms and other soil organisms, groundwater pollution, pest and disease resistance, and quality of the harvest.

Studies have also shown that crops grown in healthy soil do not have to be sprayed with toxic chemicals to protect them from pest and diseases. And using fewer chemicals translates into both a reduction in the possibility of food contamination and the elimination of the exposure to these dangerous chemicals by factory workers, farmers, and home gardeners.

You can have productive, fertile soil without knowing anything about the fine points of soil Chemistry and mineral balancing, as long as you understand the importance of caring for the soil organisms. An astonishing number and variety of creatures - from bacteria and fungi to earthworms and moles - make up the soil community. These organisms are constantly growing, reproducing, and drying in every crumb of soil - billions in each gram of healthy topsoil.

To really understand how soil affects the growth of crops and plants, it helps to know a bit about some of its characteristics, such as what it's made of. The basic composition of any soil can be broken down into two major components: solids and spaces. The solids include soil minerals and organic matter, the spaces contain air and water. The exact proportions of these parts vary from soil to soil, and they can have a great influence on plant growth.

THE SOLID PART OF SOIL

About 90 percent of the solid part of soil is composed of tiny bits of rocks and minerals from which the soil was foamed. These particles are referred to as sand, silt, or clay, depending on their size. Most soils contain a mixture of these three types of particles. These components of a soil are largely unalterable - there's not much you can do to change them.

The remaining 10 percent of the solid part of soil is the organic fraction. This small part of the soil has a tremendous influence on the soils ability to support plant and crop growth. How you manage your soil has a profound influence on the amount and quality of organic matter it contains.

The organic fraction of soil is a dynamic substance, constantly undergoing change. This vital bit consists of living organisms, including plant roots and bacteria as well as dead plant residues and other wastes. The total weight of the living organisms in the top 6 inches of an acre of soil can range from 5,000 pounds to as much as 20,000 pounds.

The continual decomposition of organic residues results in the formation of humus and the release of plant nutrients. The fertility of your soil - its capacitor to nurture healthy plants and crops - depends on the health, vitality, and diversity of the organisms that live, grow, reproduce, and die in the soil. Through the activities of soil microbes, which can number in the billions in every gram of healthy topsoil, the basic raw materials needed by plant and crops are made available at the right time and in the right form and amount.

Soil health and humus are interrelated: Health is the vitality of the soil's living population, and humus is the manifestation of its activities. Humus is produced by bacteria and fungi as they consume organic material in the soil. These elements keep the soil healthy and easy to work, and help the soil to hold water.

The billions of organisms that make up the soil community are dependent on you for their health and well-being. If you provide for their basic needs and cultivate properly to avoid disturbing them too much, the soil organisms will thank you with a healthy, productive soil that your plants and crops will thrive in.

SPACE FOR AIR AND WATER

About half the volume of good soil is pore space - the area between particles where air and water can penetrate. The pore space generally contains an equal volume of water, which clings to the surface of soil panicles, and air. Keeping a healthy balance of air and water by maintaining a loose, open soil is critical for good root growth and the health of the soil community. All the fertilizer in the world won't solve the problems of dense, compacted soil that is deficient in pore space.

Air. Air is crucial for soil health, although certain bacteria can live without it. No amount of fertilizing can compensate for lack of air. Plant roots can't take full advantage of available nutrients if they are suffocating.

Water. Water is also strictly essential, but too much water can mean too little air The ideal biological environment consists of a thin film of moisture clinging to each soil panicle, with lots of air circulating between the particles. Rain and irrigation add needed soil moisture, but good soil structure is required to conduct moisture upward from reserves in lower soil layers.

THE SOIL COMMUNITY

The living part of the soil is just as critical to Plant growth as the physical soil structures. Soil microorganisms are the essential link between mineral reserves and plant growth. The cycles that pen nit nutrients to flow from soil to plant are all interdependently and they work only with the help of the living organisms that constitute the soil community.

Soil organisms, from bacteria and fungi to protozoans and nematodes, on up to mites, springtails and earthworms, perform a vast array of fertility-maintenance tasks. Organic soil management aims at helping soil organisms maintain fertility; conventional (non-organic) soil management merely substitutes a simplified chemical system to provide nutrients to plants. Once a healthy soil ecosystem is disrupted by the excessive use of soluble synthetic fertilizers, restoring it can be a long and Costly process. In many cases, the excessive use of energy-intensive petroleum-based fertilizers and pesticides has destroyed the biological fertility of soil, so growers use ever-larger amounts of these materials to sustain crop growth.

 

Like all living things, the creatures of the soil community need food, water, and air to carry on their activities A basic diet of plenty of organic material, enough moisture, and well-aerated soil will keep their populations thriving.

Soil creatures thrive on raw organic matter with a balanced ratio of carbon to nitrogen, about 25 to 30 parts carbon to 1 part nitrogen. Carbon, m the form of carbohydrates, is the main course for soil organisms. Given lots of it, they grow quickly scavenging every scrap of nitrogen from the soil system to go with it. That's why adding lots of high-carbon materials to your soil can cause nitrogen deficiencies in plants.

In the long term, carbon is the ultimate fuel for all soil biological activity and therefore of humus formation and productivity. A balance supply of mineral nutrients is also essential for soil organisms, and micronutrients are important to the many bacterial enzymes involved in their biochemical transformations.

LIFE IN THE ROOT ZONE

The health of plants, crops, animals, and people all begins with healthy soil. Each organism - above and below ground - has a role to play in the soil ecosystem. Here's what they do: Producers create carbohydrates and proteins from simple nutrient elements, almost always by capturing energy from sunlight through photosynthesis. Green plants, including blue-green algae are the producers for the soil community.

Consumers are just about everyone else: all organisms big and little, that depend on the food created by green plants.

Decomposers perform the critical function of bringing the basic chemical nutrients full circle - from consumers back to producers. They are primarily bacteria or fungi and are found almost exclusively in soil. Microbial decomposers account for about 60 to 80 percent of the total Soil metabolism. Without them, life would grind to a halt as we suffocated in our own wastes.

Some of the organisms we know that are critical to soil health include bacteria, actinomycetes, fungi, algae, nematodes? and earthworms.

Bacteria

Bacteria are the most numerous and varied of soil organisms. There ant anywhere from a few hundred million to three billion in every gram of soil. Under the right conditions, they grow at an astonishing rate and can double their population every hour. The top 6 to 8 inches of soil may contain anywhere from 200 pounds to 2 tons of live bacteria per acre.

Bacteria vary in their requirements for air, but most beneficial ones need some air to thrive. Bacteria need adequate calcium and a balance of micronutrients, which are essential to the enzymes used to perform their biochemical tasks.

Bacteria have a virtual monopoly on three basic soil processes that are vital to higher plants and crops: nitrif1cation, sulfur oxidation, and nitrogen fixation. Bacteria, which occur by the millions in each gram of soil, transform nitrogen and sulfur to a form usable by plants and crops.

 

Nitrification. Nitrogen occurs in several different forms in the soil, but some of them are unavailable to plants and crops until they are transformed by bacteria. Soil organic matter, for example, holds nitrogen in the form of complex proteins. Bacteria and other organisms help to break down these proteins into the form of ammonium.

 

Sulfur Oxidation Sulfur undergoes similar chemical and biological transformations in the soil. Specialized bacteria turn organic sulfur compounds into sulfates, the form most usable by plants and crops.

Nitrogen Fixation. Nitrogen-fixing bacteria transform elemental nitrogen from the atmosphere into protein and eventually make it available to other organisms. To make synthetic fertilizers, humans imitate this process at a high energy costly burning tremendous amounts of natural gas to synthesize ammonia from atmospheric nitrogen. Some nitrogen-fixing bacteria live in symbiosis with leguminous plants, and other nitrogen-fixing bacteria live free in the soil. Bacteria transform nitrogen from the atmosphere into a form usable by plants and crops.

Anion Nutrients

Reserves of anion nutrients are held in the organic portion of the soil and are released to plants and crops through the decay of organic matter or through air and water. Soil anions, which form acids in solution, continually change in form and quantity. As the major building blocks of proteins and carbohydrates, anions are required in larger quantities than are cation nutrients. Elements that form soil anions include nitrogen, carbon, phosphorus, and sulfur.

Nitrogen. Nitrogen tends naturally towards the gaseous state as its most stable and plentiful form. Although plants and crops cannot use atmospheric nitrogen directly, certain soil microbes such as the rhizobium bacteria are able to capture it from the air and transform it into a biologically useful form: the nitrate anion. The nitrate form, which is present in the soil solution, is extremely transitory and will fluctuate significantly from day to day and even at different times of the day.

Carbon. Carbon is the major constituent of plant (and animal) tissue. It is the food consumed by plants and crops more than any other mineral. Although abundant in the organic fraction of the soil, carbon is taken in by plants and crops almost entirely from the atmosphere as carbon dioxide. Some of the carbon dioxide reacts in the soil to produce carbonate and bicarbonate anions

 

Phosphorus. Although more mineral-like than other anion nutrients, phosphorus is easily immobilized ill the soil through its tendency to form insoluble compounds with calcium and other minerals. It is most readily available to plants and crops when released gradually through the decomposition of organic matter. Its relative mobility means that distribution of phosphorus throughout the soil is only accomplished through the movement of earthworms and other soil organisms.

Sulfur. Sulfur, an essential component of protein and fats, acts a lot like nitrogen in the soil ecosystem and is particularly important for nitrogen-fixing microorganisms. Sulfur deficiency is rarely a problem, especially where adequate soil organic matter levels are maintained. Acid rains containing sulfur compounds released by coal-burning industrial plants also adds sulfur to the soil

Cation Nutrients

Cation nutrients tend to be metallic mineral elements, important for both plant and microbial nutrition as components of enzymes. Canon nutrients are generally water-soluble and enter the soil either through the recycling of organic matter or by addition of mineral nutrient sources. Cations are called base elements because they form bases in solution. The major cation nutrients are calcium, magnesium, and potassium. These nutrients are essential for uptake and metabolization of the anion nutrients.

Calcium. Calcium is essential for nitrogen uptake and protein synthesis in plants and crops. It also has a role in enzyme activation and cell reproduction.

Magnesium. Magnesium is an essential part of the chlorophyll molecule. It's necessary for phosphorous metabolism and enzyme activation.

Potassium. Potassium is essential for carbohydrate metabolism and cell division. It regulates the absorption of calcium, sodium, and nitrogen.

Fungi

Molds, yeasts, and mushrooms are all fungi. Although they are classified as plants, they do not contain chlorophyll and so must depend on other plants for their nourishment. Yeasts are not common in soil, but molds and mushrooms play important roles. Molds may be as numerous as bacteria in soil. In fact, under conditions of poor aeration, low temperature, and acidity, molds outnumber bacteria because they tolerate these conditions more easily. Some molds are detrimental to plant growth. In the soil, molds are especially important for organic matter decomposition and humus formation.

Connecting Plants and Crops to Soil

There are many ways in which plant roots interact with the rest of the soil community. Most of the important soil process, especially nitrogen fixation and mycorrhizal associations, take place in the root zone. Roots serve as homes for nitogen-fixing bacteria and phosphate scavenging mycorrhizal fungi, which help enrich the supply of these nutrients for the whole soil community. Growing roots are also continually sloughing off dead tissue, an excellent food for mlcroorganisms.

Soil pH and Fertility

Monitoring soil pH can help you maintain proper mineral balances. The pH scale, from 1 to 14, is a measure of the acidity or alkalinity of soil, determined by the concentration of hydrogen ions in a water or salt solution. A pH of 7.0 is neutral. Acidity is indicated by a pH below 7.0, and pH values of over 7.0 indicate alkalinity.

The pH of your soil has a great effect on what nutrients are available to your plants and crops. The optimum pH range is t.8 to 8.3. This pH range is also ideal for many soil organisms, including earthworms and bacteria. Keeping your soil at a balanced pH is a major part of maintaining soil health and fertility.

BALANCING NUTRIENTS

Most commercial fertilizer labels include only the familiar three numbers, such as 20-10-10 that stand for three major nutrients - nitrogen (N), phosphorus (P), and potassium (K). These three numbers are commonly know as the NPK analysis of that fertilizer. You may sometimes see them called nitrate, phosphate, and potash: These terms refer to the same nutrients, but in different chemical forms - the forms in which they usually occur in synthetic fertilizer formulas.

If you compare the NPK numbers on a bag of chemical fertilizer with those on a bag of organic fertilizer, you may wonder why the organic bag's NPK numbers are so low. Most organic materials vary considerably in their composition. Their nutrients are low in solubility, so they are released slowly over time. While this is desirable from the soil's point of view, Commercial fertilizer labels may legally claim only the immediately available nutrient content.

Soil fertility requires nutrients to exist not only in sufficient quantities, but also in balanced form Too much of one nutrient may lock up or interfere with the absorption of another. The ideal proportion of anion nutrients is the balance that is found in humus - 100 parts Carbon: 10 parts nitrogen: 1 part phosphorus: 1 part sulfur. The ratio of nitrogen to phosphorus is important to proper plant nutrition because inadequate nitrogen slows the growth of roots and, therefore, their ability to reach phosphorus supplies.

New information is continually being discovered about previously unknown interactions between major and minor nutrients in the soil ecosystem. Micronutrient problems are often a result of imbalances. S Ma nitrogen, another for phosphorus, and yet another for potassium) can lead to soil imbalances and reduced availability of micronutrients. The best nutrient sources contain a balance of many different nutrients.

To reiterate, the billions of organisms that make up the soil community are dependent on you for their health and well-being. If you provide for their basic needs and cultivate properly to avoid disturbing them too much, the soil organisms will thank you with a healthy, productive soil that your plants and crops will thrive in.

"Feed the soil, not the plant" is fundamental to organic soil management, but standard fertilizer recommendations are based only on plant responses to the fertilizers. They fail to consider such things as effects on earthworms and other soil organisms, groundwater pollution, pest and disease resistance, and quality of the harvest.

Studies have also shown that crops grown in healthy soil do not have to be sprayed with toxic chemicals to protect them from pest and diseases. And using fewer chemicals translates into both a reduction in the possibility of food contamination and the elimination of the exposure to these dangerous chemicals by factory workers, farmers, and home gardeners.

Scientists have steadily accumulated evidence that plants, pest and disease resistance is strongly related to the fertility of the soil in which they grow, with the soil's humus content being of primary importance. Studies have demonstrated improvements Oil the health of animals whose feed was grown on biologically active soil free from chemical fertilizers. In comparisons between potatoes grown organically and those grown using artificial fertilizers, the organically grown produce has consistently shown superior storage qualities. Organically grown grains generally gave a higher content of dry matter, which improves their storage ability and nutrition.

MITY-GRO is a soil rejuvenation fertilizer, soil enhancer and soil conditioner all in one. It is environmentally safe non-chemical, non-toxic, and will not burn foliage or roots. MITY-GRO will produce substantial and beneficial changes in such areas as: Crop yield per hectare, length of time for crop to mature, average produce size of crop, cost per hectare to fertilize, and reduction of the need for water.