HUMIC SUBSTANCES – 1

Overview

Try planting seeds in pure clay retrieved from the bottom of a 2’ deep hole. There is no plant growth here, no matter how much N-P-K is applied. It is not possible to grow a crop in soil in the complete absence of organic carbon (humus).

In the production of a fertile soil, organic substances play a direct part as they are the sources of plant nutrients which are liberated in available forms during mineralization. The rise in popularity and use of synthetic chemical/mineral fertilizers enabled growers to directly supply plant nutrients to the soil, and rapid growth in agricultural productivity occurred. As a consequence, the importance of soil organic matter was neglected. Humanity has yet to incur the full brunt of this consequence as population soars and food supply quantity dwindles, and the nutritional value of harvests decreases.

No Structure

Humus is a structureless (amorphic) colloidal material resulting from the decomposition (humification) of any type of dead organic matter (mostly plant residues and animal remains). It is a complex mixture including proteins, lignin (plant cell walls); fats, carbohydrates, and organic acids. These acids, humic acids and chelates, provide a storehouse of essential plant nutrients. It helps make some nutrients more soluble and available to plants. It provides high water absorption and holding capacity and contributes to good soil structure. It buffers the soil and protects plants from drastic changes in pH. Humus and soil life (microbes and larger creatures) work together for the benefit of all living plants grown in every type of soil.

Organic Carbon

Organic carbon is created from the breakdown of organic matter (usually in the form of crop residues) principally by diverse populations of bacteria, actinomycetes and fungi. The conversion and availability of all mineral elements in soil are related to, and regulated by, this natural system of decay on/in the soil.

This is the environment necessary for the decomposing micro-organisms to flourish. Crop residues are converted into carbon dioxide, carbonic acid and numerous mild organic acids (such as folic acid). These acids, stored in the humus complex, are necessary to convert, chelate, and release soil minerals. Everyone knows that plants need light, warmth and moisture, in addition to good fertile soil laden with the whole set of macro and micro elements, for plants to flourish (not just ‘survive’). But the real problem is that assimilation of those elements is impossible without some special organic substance, which science calls "humus". What you buy in a store bag is NOT humus, although it might contain a small amount.

The main compounds in humus are humic acids; which have originated during the decomposition of plant and animal residues by microorganisms, under mostly aerobic (but also in anaerobic conditions), usually in soils, composts, peat bogs, and water basins.

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Organic Matter

The importance of organic matter to make soil into dirt is not a recent discovery. Fertility of dirt (sol) in early agricultural systems was based on the recycling of organic wastes. Plowing stubble back into the earth. It was well-known that the addition of decomposed organic materials back into soil improved plant growth.

Besides eventually becoming a source of nutrients for the plant via microbial activity, organic matter has a fundamental effect on the physical properties of the soil (water-holding capacity) and determines to a large degree, such properties as the cation exchange capacity (CEC) and buffering or mediating other soil properties such as salts. These properties are of great importance, not only in controlling the uptake of nutrients by the plant and the retention of nutrients in the soil, but also in suppressing the deleterious effect of soil acidity and alkalinity.

Effect of Management Practices on Soil Organic Matter.

It is well-known now, that commercial agricultural cultivation of soils usually causes a decrease in the organic matter content and significant effects of erosion and pollution from using synthetic chemicals. For most soils, a high level of organic matter is maintained only by grass species. Conventional sources of applied organic matter such as farm manures or crop residues are not normally used due to lack of availability or prohibitive cost of spreading them or plowing them under after a poor harvest.

Other Sources of Humic Matter:

Some humate products for agricultural use are produced through mineral sand mining of ancient deposits. The end product contains a majority of organic material (concentrated humic acid) mixed with smaller amounts of mineral matter. Another product is compost ‘tea’ – the liquid “mirror image” of the compost it is derived from when fresh. If allowed to become anaerobic, microbe populations will decrease, but plant nutrition and humic content can remain viable for many months (even years) if stored properly.

Humate concentrates (such as compost tea from well-managed aged compost) provide many of the advantages of conventional organic matter sources with less handling problems, especially in situations where there is no feasible alternative to purchasing additional supplies of humus such as is found in aged/finished compost. Ancient humic acid deposits in Russia and New Mexico are dwindling, and no new deposits have been located in many decades.

Humates have been demonstrated to have very favorable effects on plant tissue nutrient balance, fertilizer uptake, both top and root growth, crop yield and quality, for a large variety of field and horticultural plants. If we defined humus as the base of fertility, we can define compost tea products as a concentrate of the vital strength of humus, produced by nature during evolution. The importance of organic matter in soil/dirt cannot be over emphasized. Soil life depends in large part on a steady supply of organic matter. The microbial and larger ‘critters’ in soil all depend, in some way, on the same decomposing organic matter.

© Robert C. Moore ~ All Rights Reserved

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COMPOST CONTAINMENTS
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