We at Watson Ranch pride ourselves on staying up to date on the latest Organic Research.  This page is for you to enjoy and to help you understand what Organics can do for you.

The Importance of Biological Life and it's Many Functions Within the Soil

The development of soils from original rock materials is a process in which biological activity plays on important role.

The soil aggregates are formed by both physical forces and by binding agents, principally products of the biological decomposition of organic matter.  The latter types are more stable and resist, to a greater degree, the destructive forces of water and cultivation.

Besides their role in soil-forming processes, soil organisms make an important contribution to plant growth through their effect on the fertility level of the soil.  Particularly important in this respect are the microscopic plants (microflora) which function in decomposing organic residues and releasing available nutrients for plant growth.

Some important kinds of microorganisms are bacteria, fungi, actinomycetes, and algae.  All of these are present in the soil in very large numbers when conditions are favorable.  A gram of soil may contain as many as 4 billion bacteria, 1 million fungi, 20 million actinomycetes, and 300,000 algae.  These microorganisms are important in the decomposition of organic materials, the subsequent release of nutrient elements, and the fixation of nitrogen from the atmosphere. 

Nitrogen does not exist in the soil in a natural mineral form as do other plant nutrients.  It must come from the air, which contains approximately 78% nitrogen.  This means that there are about 35,000 tons of nitrogen over every acre of land.  In order for crops to utilize this nitrogen, it must be combined with hydrogen or oxygen, which results in the formation of ammonia (NH3) or nitrate (NO3).  This process is called nitrogen fixation.  Inside the plant these substances are converted into amino acids, which are combined to form proteins.  Any unbalanced condition, either too much or too little, in the supply of nutrients will upset this process.

Many reactions involving nitrogen occur in the soil; most of them are the result of microbial activity.  There are two distinct types of bacteria symbiotic and non-symbiotic.

The symbiotic bacteria are those associated with leguminous plants.  In return for the food and minerals they get from the plant, these bacteria supply the plant with part of its nitrogen needs, generally not more than 50 to 75% at it.

The non-symbiotic bacteria live independently and without the support of higher plants.  There are two different types of non-symbiotic bacteria:  The aerobic, which requires oxygen, and the anaerobic, which do not need oxygen.  These bacteria can supply as much as 30 lbs of nitrogen per acre per month. 

Nitrogen is also returned to the soil in the form of organic materials, which are derived from former plant and animal life and animal wastes.  These materials are largely insoluble in water and are reduced by biological decomposition, oxidation, reduction, and are finally mineralized to nitrate nitrogen for plant use.  This recycling of nitrogen from organic matter to soil to growing plants is a part of the nitrogen cycle.

Soil bacteria are of special interest because of their many varied activities.  IN addition to the group of bacteria which function in decomposing organic materials (heterotropic  bacteria), there is a smaller group (autotropic bacteria), which obtain their energy from the oxidation of mineral materials such as ammonium, sulfur and iron.  This latter group is responsible for the nitrification process  (oxidation of ammonium to nitrate nitrogen) in the soil, a process which is vitally important in providing nitrogen for the growth of agricultural crops.

Nitrogen fixing bacteria also play an important role in the growth of higher plants since they are capable of converting atmospheric nitrogen into useful forms in the soil.  Nodule bacterial (rhizobia) live in conjunction with roots of leguminous plants, deriving their energy from the carbohydrates of the host plants, and fix nitrogen from the soil atmosphere.  Under most conditions, free living bacteria (azotobacter and clostridium) also fix atmospheric nitrogen, although to a lesser extent than the rhizobia bacteria.

Because of the important contributions made by the bacteria to the fertility level of the soil, life of higher plants and animals could cease if the functions of bacteria were to fail. 


Special emphasis should be given to soil bacteria because they are possibly the most important of all organic life in the soil.  They are the simplest types of plant life and also the most numerous.  They grow simply by doubling their length and dividing.  Under normal conditions a bacterium can divide in about 20 to 30 minutes.  It is possible under favorable conditions to get many millions of bacteria from only one bacterium in the course of 24 hours.  Soils contain hundreds of different varieties of soil bacteria.  They have a large variety of sizes and shapes.  Some are round, others, rod-like; still others may have tiny hair like projections known as flagella which permit the bacteria to move about in the soil solution.  Several billion bacteria may be found in one gram of soil.  Some varieties are aerobic while others are anaerobic.  The aerobic type needs oxygen from soil air, while the anaerobic types take their oxygen from chemicals containing oxygen (nitrate, NO 3).

Not only are bacteria important for decay purposes, that is, reduction organic matter into simpler compounds, but they are very important in such processes as nitrification, which is the changing of ammonia compounds into nitrates.  Nitrogen fixation, the forming of nitrates from nitrogen found in the soil air, is another important function carried on by the nitrogen-fixing types of bacteria.

Because of the importance of bacteria to the fertility level of the soil, higher plants and animals would cease to exist without them.

Source:  A & L Agronomy Handbook

Organic Farming Beats No-Till?
By Don Comis
July 10, 2007

Organic farming can build up soil organic matter better than conventional no-till farming can, according to a long-term study by Agricultural Research Service (ARS) scientists.

Researchers made this discovery during a nine-year study at the Henry A. Wallace Beltsville Agricultural Research Center (BARC), Beltsville, Md. BARC is operated by ARS, the U.S. Department of Agriculture's chief scientific research agency.

Plant physiologist John Teasdale, with the ARS Sustainable Agricultural Systems Laboratory in Beltsville, was surprised to find that organic farming was a better soil builder than no-till. No-till has always been thought to be the best soil builder because it eliminates plowing and minimizes even light tillage to avoid damaging organic matter and exposing the soil to erosion.

Organic farming, despite its emphasis on building organic matter, was thought to actually endanger soil because it relies on tillage and cultivation—instead of herbicides—to kill weeds.

But Teasdale's study showed that organic farming's addition of organic matter in manure and cover crops more than offset losses from tillage.

From 1994 to 2002, Teasdale compared light-tillage organic corn, soybean and wheat with the same crops grown with no-till plus pesticides and synthetic fertilizers.

In a follow-up three-year study, Teasdale grew corn with no-till practices on all plots to see which ones had the most-productive soils. He found that the organic plots had more carbon and nitrogen and yielded 18 percent more corn than the other plots did.

Read more about the research in the July 2007 issue of Agricultural Research magazine.

Source  USDA
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