Endogenous organic matter in soil mainly comes from animal, plant and microbial residues and excretory secretions, while exogenous organic matter mainly depends on manufactured organic fertilizer. Due to continuous cultivation and blind pursuit of yield, the organic matter content in China's land decreases year by year. Even in some places, the soil is compacted, salinized seriously, the soil fertility decreases year by year, and the fertile soil becomes barren and dead. China's agriculture lays particular stress on the application of chemical fertilizers, ignoring the harmful effects of organic fertilizer input, and is considering the development of China's sustainable agriculture. Therefore, it is proposed that in future fertilization, organic and inorganic fertilizers should account for seven points and three points. It is not harmful to nature and the earth. Only by nourishing the land can 1.3 billion people be fed.
Organic matter is an important indicator of organic fertilizer. How does it affect soil and plants in soil?
1. The transformation of organic matter in soil: Organic matter entering the soil undergoes complex transformation processes under the action of microorganisms, including mineralization and humification processes.
1. Mineralization process of organic matter: Soil organic matter is decomposed into carbon dioxide, water, ammonia and mineral nutrients (simple compounds or ions such as phosphorus, sulfur, potassium, calcium and magnesium) by various enzymes secreted by microorganisms, and energy is released at the same time. This process provides nutrients and active energy for plants and soil microorganisms, directly or indirectly affects soil properties, and also provides a material basis for the second process (humification process).
The mineralization process requires two functions of water and enzymes. On the one hand, water can wash out the soluble substances in soil organic matter. These substances include simple sugars, organic acids and salts, amino acids, proteins and inorganic salts. On the other hand, enzymes (oxidoreductase, invertase and hydrolase) are the motive force of organism metabolism, and they play a great role in the process of organic matter transformation. Organic matter is decomposed by microorganisms to produce various enzymes and organic acids. They promote plant growth and plant cell synthesis. Without enzymes, there will be no life. At the same time, enzymes are also an important medium for the transformation of organic matter into humus.
2. Humus process of organic matter:
The transformation of organic matter into humus in soil is a very complex process, which is to transform simple and single organic compounds into complex and stable organic compounds and become organic colloids. Soil organic colloid is an indispensable cementing material for the formation of water-stable aggregate structure, so it helps clay to form a good structure, thus changing the soil pore condition and water-air ratio. In addition, due to the dark color of organic matter, it is conducive to heat absorption and can increase ground temperature. It can conserve water and fertilizer and improve the buffer of soil to acid and alkali.
2. Organic Fertilizer in Soil
1. The main source of plant nutrients. Organic matter contains all kinds of nutrients needed for plant growth and development, especially nitrogen in soil. More than 95% of nitrogen is in organic state in soil. In addition, organic matter is also an important source of phosphorus, sulfur, calcium, magnesium and trace elements in soil.
2. Enzymes and humic acids produced during the decomposition of organic matter can enhance plant respiration, improve the permeability of cell membranes, enhance the absorption of nutrients, and promote plant growth and development.
3. Improve soil structure. Humus in organic matter is the main cementing agent of soil aggregates, which can promote the formation of good structure. Organic matter can also increase heat absorption capacity, improve soil fertility and create appropriate soil tightness.
4. Improve the ability of soil to retain water and fertility. Soil organic matter belongs to organic colloid, which has strong adsorption capacity and can absorb a large number of nutrients and water.
5. Promoting the activities of soil microorganisms. Soil organic matter supplies the energy and nutrients needed by soil microorganisms, which is conducive to the activities of microorganisms.
Soil with high content of soil organic matter has a high level of soil fertility, which not only provides abundant nutrition for crop growth, but also has a strong ability of water and fertilizer conservation. It can reduce the loss of nutrients, save the amount of chemical fertilizer and improve the utilization rate of fertilizer. Therefore, we should do everything possible to increase the application of organic fertilizers, improve the content of soil organic matter, so as to give full play to the yield-increasing benefits of chemical fertilizers.
In short, organic matter in soil can produce various benefits only through microbial decomposition, and the organic matter that can not be decomposed is invalid organic matter. Like lignite and peat, there are only indicators in the laboratory, but the soil can not be decomposed by microorganisms, that is, ineffective organic matter.
The decomposition of organic matter in fertilizers can not be separated from the role of enzymes. Enzymes are important media for mineralization of organic matter to inorganic salts, for transformation of organic matter into humus, and for inorganic transformation into nutrients to promote cell synthesis. So enzymes should be another important indicator of organic fertilizer. Organic fertilizer should contain organic matter and enzymes, so it should be called organic enzymatic fertilizer.
At the same time, it is hoped that the Ministry of Agriculture will revise the standard of organic fertilizer, not only requiring the content of carbon element in organic fertilizer, but also requiring the content of enzymes in organic fertilizer. Now many enterprises use weathered coal as organic fertilizer raw material, and even some enterprises use carbonized organic material raw material. In the process of organic matter decomposition, enzymes can not be produced, and can not be absorbed and utilized by crops. The environment is destroyed and the soil is delayed.
Only the fertilizer containing enzymes and organic matter can be a living fertilizer, a real organic fertilizer, and a soil that can breathe, metabolize and live on.