Organic matter waht does it makes to soil

With the application of organic matter, soils have everything to gain and nothing to lose. Indeed, it is probably unheard of that organic materials, even at high doses, ever harm soils. However, very few people are convinced of the benefits from organic matter. Why?

Maybe, one of the reasons is that many effects of organic matter are not immediate and easily discernible. The effects, particularly on crop yield, gradually builds up over the years and may not even show during the first cropping. Organic matter increases nutrient supply of soils and improves their retention and availability through dissolution of minerals and complex compounds, thus preventing their reaction with other soil elements. In acid soils, organic matter reduces the toxicity of aluminum ions. Likewise, organic matter triggers a frenzy of activity of beneficial soil organisms because organic matter is their source of energy and carbon. The benefits from all these chemical and biological effects are primarily made in the soil itself and takes a while before being reflected in crop yields.

The effects of organic matter on physical properties of soils are perhaps more easily seen. Being a binding agent, humus is the final product of organic matter decomposition. Humus promotes formulation and stability of soil aggregates, thus improving tilth or ease of cultivation. This correspondingly increases water absorption and storing capacity which can consequently reduce soil runoff and erosion. This ranulating effect is especially important for very sandy and heavy clay soils. Hence, the overall effects on physical qualities of soils are: (1) well granulated structure, (2) good aeration and drainage, (3) improved water absorption, (4) reduced run-off, (5) easier tillage and (6) better crop growth.

How do soils lose their organic matter content? As soon as soils are cultivated, the organic matter starts to decline due to its microbial oxidation. Such decline is accelerated by burning, erosion and leaching. However, high levels can be maintained by incorporating crop residue or through green manuring (plowing under of green plant material, usually legumes), cover cropping, mulching and crop rotation which sustain soil productivity. (I.B. Dimaporo)

Source: http://community.uplb.edu.ph