Reasons for the combination of organic and chemical fertilizers

The combination of chemical fertilizers and organic fertilizers is a scientific fertilization decision, which is determined by the nature and characteristics of organic fertilizers and chemical fertilizers. The characteristics of organic fertilizers and chemical fertilizers are now compared and analyzed as follows:

(1) Most high-quality organic fertilizers contain large amounts of organic substances. Applying high-quality organic fertilizers all year round can not only increase the content of organic matter in the soil, but also make the soil organic matter constantly renewed, thus improving the physical and chemical properties of the soil. The role of soil improvement: While chemical fertilizers do not contain organic matter, there is generally no direct effect of soil improvement. This shows that organic fertilizer is the basic material for building high-yield farmland.

(2) There are many kinds of organic fertilizers and they contain a lot of nutrients. People often call them complete fertilizers, but organic fertilizers have very low nutrient content. About 1000 kg of quality manure contains only 5 kg of nitrogen (N), while chemical fertilizers provide nutrients. The content is high. For example, 100 kg of urea contains 46 kg of nitrogen. According to 1000 kg, it contains 460 kg of nitrogen, 92 times that of manure. However, the disadvantage of chemical fertilizers is that it contains a relatively single type of nutrients. Take urea, it contains only nitrogen in the three elements of nitrogen, phosphorus and potassium, does not contain phosphorus and potassium, and superphosphate contains only phosphorus, nitrogen and potassium, alone can not meet the needs of the crop.

(3) The nutrients in organic fertilizers are mostly in organic state and need to be continuously decomposed by soil microorganisms before they can be converted into nutrients that crops can absorb and use. As a result, the fertilizer efficiency of organic fertilizers is slow, but it lasts for a long time and has an aftereffect; The nutrients contained in most chemical fertilizers are water-soluble and crops can be directly absorbed and utilized. Therefore, the chemical fertilizer has a rapid and effective fertilizer effect, and can provide more nutrients when the crop needs nutrients most, but its fertilizer effect is short and cannot be sustained. It can be seen that rational application of chemical fertilizers is a material guarantee for increasing the yield of crops.

(4) Organic fertilizers need to be decomposed and transformed to release nutrients for crop absorption. Therefore, organic fertilizers are not utilized in the current season. For example, the nitrogen utilization rate of decomposed organic fertilizer is only 20% to 30%, but it has less nutrient loss when decomposed and long time for supplying fertilizer; while the nutrient content in chemical fertilizer is high, most of them are available nutrient, and they easily pass through volatilization and leaching. Losses (especially nitrogen fertilizers) are lost, resulting in low utilization of fertilizers in the current season. For example, the nitrogen fertilizer utilization rate is generally about 35%, phosphorus fertilizer is about 10% to 25%, and potassium fertilizer is more than 40%.

By comparing the two, it is easy to see that organic fertilizers and chemical fertilizers have their own advantages and disadvantages, and some of the advantages of organic fertilizers are the drawbacks of chemical fertilizers, and some of the advantages of chemical fertilizers are the shortcomings of organic fertilizers. Therefore, the combination of the two can complement each other and give full play to their own characteristics. This is the necessity and scientific reason for the combined use of the two.