The benefits of Organic Matter are widely misunderstood. Although dairymen regard cow manure as a waste, commercial farming operations value it as a soil amendment; while many growers value it only as a fertilizer. As a source of primary nutrients, though, Organic Matter offers much less, pound for pound, than inorganic fertilizer. So what are its benefits?
First, Organic Matter does contain primary nutrients -Nitrogen, Phosphate, and Potash – but in small amounts. For example, a grower would need 8 times as much horse manure as compared to a 5-10-10 fertilizer in order to supply a given amount of nitrogen. If you rely solely on manure to supply primary nutrients, you’ll need a pile! (literally.) Most growers supplement manure with other fertilizers.
Primary nutrients don’t supply all of the plant’s requirements, though. Secondary elements, such as; sulphur, calcium, and magnesium, are required in substantial amounts. Micronutrients; including zinc, boron, iron, and copper, are also needed in minute quantities. Organic Matter is usually an excellent source of these elements, as most inorganic fertilizers are not supplying them.
Not only does Organic Matter supply nutrients, it helps hold them in the soil. Particles of humus derived from Organic Matter carry a negative electrical charge which allows them to combine with many plant nutrients that carry a positive electrical charge. Sand is electrically neutral, which explains why it doesn’t hold nutrients well. Adding Organic Matter to sandy soil greatly enhances that soil’s ability to catch and retain nutrients and water.
The most important benefit of Organic Matter is as a soil conditioner. Mixing Organic Matter into a sandy soil is like introducing thousands of tiny sponges that help retain moisture. Organic Matter also helps loosen and aerofy a compacted clay soil.
Organic Matter also transport useful microbial hitchhikers. These living components of organic matter manufacture glues-like substances that cement soil particles into crumbs (aggregates). Crumbly soil is ideal as far as most plants are concerned because its structure allows it to hold both air and water. Thereby allowing roots to move easier through the soil profile and helping the plant conserve energy.
Once dissolved in water, most inorganic fertilizers are quickly available to plants. But slow release fertilizers, like Organic Matter, are also beneficial because they provide small amounts of nutrients over several years. When Organic Matter is applied each year, you’ll maintain a small reserve of nutrients that plants can draw on throughout their growing period.
Organic Matter does have some drawbacks though. Although, careful selection, handling and use can minimize these drawbacks will accentuating the benefits of Organic Matter use.
09 Feb 2007 The Organic Gardener