The main functional performance of soil organic matter
1. Fertilizer and water retention are the carrier of water and fertilizer
2. Carriers and energy sources of microorganisms
3. Promote the formation of soil aggregate structure
Subdivided branches of organic matter
1. Primitive state, including protein, fat, starch, cellulose, hemicellulose and lignin, etc.
2. Semi-transformed state, that is, a state that is different from the basic structure of the original state
3. Humus, that is, the substance with soil activity generated by the transformation of microorganisms and physical and chemical action, the so-called activity has ion exchange, cohesiveness and adhesion.
It is humus that directly acts on plants, and the first two items must be converted into humus in order to be utilized
This transformation is decomposed by microorganisms, which consume 50%-70% (calculated at 60%) of the carbon in the organic matter during the mineralization and humification process. The weight of carbon in organic matter is 55%-60% (58% is generally calculated for laboratory testing). Therefore, the weight of carbon lost by soil microorganisms slowly decomposing humus is 58%x60%=34.8% of the carbon element that has not been humified, and the carbon element here is the core value of the current popular carbon fertilizer.
Therefore, in the same qualified organic fertilizer, the proportion of humus in organic matter has become the core content of judging the cost performance of organic fertilizer.
The main way to increase soil organic matter
1. Straw returning to the field
2. Grass and green manure
3. Apply organic fertilizer
The above methods ultimately increase the humus of the soil, and the different organic matter states of the same weight of organic fertilizer determine the amount of humus added to the soil.
How to increase soil organic matter by 1%?
The most primitive source of soil organic matter is photosynthesis, and other links are the transfer of form and consumption, which can never be increased, so no matter how it is said, organic matter will not be conjured out of thin air. Whether it is grass or leaf litter, its contribution to soil organic matter will not exceed 0.1% per year, and the actual added value is even smaller when the consumption of soil microorganisms and the use of plants are included. Considering that the current pattern of increasing the use of chemical fertilizers is plundering organic matter, in fact, organic matter is decreasing year by year.
Therefore, the most direct and rapid way to increase organic matter is to increase organic fertilizer. How can we increase the organic matter of the soil by 1% by applying organic fertilizer? If the thickness of the tillage layer is 0.2 meters and the soil bulk density is 1.3, then the weight of one acre (667 square meters) of the tillage layer is 667x0.2x1.3=173.42 tons. The standard of organic matter in organic fertilizer is ≥30%, and if it is calculated as 50%, the amount of fertilizer required to increase the organic matter by 1% per acre of soil is 173.42x1%÷50%=3.47 tons.