The main functions of soil organic matter are:
1. Fertilizer and water retention is the carrier of water and fertilizer.
2. Carrier and energy source of microorganisms.
3. Promote the formation of soil aggregate structure.
Organic matter is a broad concept, and there are also subdivided branches
1. Original state, including protein, fat, starch, cellulose, hemicellulose, lignin, etc.
2. Semi-transformed state, that is, the state with a basic structure different from the original state.
3. Humus state, that is, the soil active substance generated by microbial transformation and physical and chemical action. The so-called activity is ion exchange, cohesiveness, and adhesion, etc.
Humus directly acts on plants, and the first two items must be converted into humus before they can be used.
This conversion requires decomposition by microorganisms. In the process of mineralization and humification, microorganisms consume 50%~70% (calculated as 60%) of the carbon element in organic matter. The weight of carbon in organic matter is 55%~60% (58% is generally used for laboratory testing).
Therefore, the weight of carbon lost by organic fertilizer that has not been humified and is slowly decomposed and converted into humus by soil microorganisms is 58%x60%=34.8%. The carbon here is the core value of the currently popular carbon fertilizer.
The proportion of humus in organic matter has become the core content of determining the cost-effectiveness of organic fertilizer
Folks can use a simple soaking method to judge the degree of humification. If it is soybean oil color (dark brown), it is good humification, and the darker the color, the better.
The main methods of increasing soil organic matter
1. Returning straw to the field
2. Growing grass and planting green manure
3. Applying organic fertilizer
The above methods ultimately increase soil humus. The different organic matter states of organic fertilizers of the same weight determine the amount of humus added to the soil.
How to increase soil organic matter by 1%?
The most common source of soil organic matter is photosynthesis. The other links are all transformations of form and consumption, which is impossible to increase. Therefore, no matter how exaggerated it is, organic matter will not appear out of thin air.
Whether it is grass or fallen leaves in nature, its contribution to soil organic matter will not exceed 0.1% per year. Taking into account the consumption of soil microorganisms and the use of plants, the actual added value is even smaller. Considering that the current general mode of increasing the application 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 the application of organic fertilizers. How to increase the organic matter in the soil by 1% by applying organic fertilizers?
Set the thickness of the tillage layer to 0.2 meters and the soil bulk density to 1.3, then the weight of one acre (667 square meters) of the tillage layer is 667×0.2×1.3=173.42 tons. The standard of organic matter in organic fertilizer by the Ministry of Agriculture is ≥45%. If we calculate it as 50%, the amount of fertilizer required to increase the organic matter by 1% per mu of soil is 173.42×1%÷50%=3.47 tons.
From this, we can see that there is no room for deception in increasing soil organic matter. There is no possibility that the so-called high-tech application of a few hundred kilograms can increase the soil organic matter by 1%.