Vegetable production: rational use of organic fertilizer

The application of organic fertilizer in vegetable production can not only achieve the purpose of continuously supplying a variety of nutrients in the root layer of crops, but also gradually improve the organic matter and buffering capacity of vegetable soil, and reduce the important role of soil-borne diseases and continuous cropping obstacles. Therefore, vegetable production has always attached importance to the application of organic fertilizer. However, in the development of modern intensive high-yield, high-efficiency and high-quality vegetable industry, in addition to continuing to maintain the input of organic fertilizer, there is also a large amount of investment in chemical fertilizer and the interactive input of large water and large fertilizer. For the sustainable development of vegetable production, it is necessary to make a new evaluation on the problems and scientific strategies of organic fertilizer application under the new situation. At present, one of the problems in the application of organic fertilizer in vegetable field is that the amount of application is large and the input of nutrients is excessive, especially the excessive input of nitrogen and phosphorus, which leads to environmental problems in some areas. For example, due to the high salt content of manure, urine and food processing residue organic fertilizer, excessive application of organic fertilizer may lead to soil salt accumulation. Second, the type of organic fertilizer is single, mostly chicken manure, pig manure and other livestock and poultry manure. Taking chicken manure as an example, it contains more nitrogen and phosphorus, but the ratio of carbon to nitrogen is very low, which is insufficient for the regulation of soil structure. Third, the safety of application. For example, garbage organic fertilizer often contains heavy metals and radioactive substances and other pollutants; animal manure organic fertilizer, due to the residue of feed additives will also have a certain amount of heavy metals, such as zinc, copper, arsenic and so on; in addition, straw organic fertilizer often contains some pathogenic microorganisms, such as harmful bacteria and insect eggs. From the market survey, it is also found that some vendors add alkali to manure and urine fertilizer in order to expand the volume of organic fertilizer, which will affect the growth of vegetables and so on. Once these organic fertilizers are applied to the vegetable field, the harmful ingredients in vegetable products may exceed the standard, which may pose a threat to food and environmental safety. One of the countermeasures for the rational application of organic fertilizer in vegetable fields is that the fertilization strategy in vegetable production should be based on the principle of combination of organic and inorganic fertilizers. First of all, grasp the nutrient content of organic fertilizer, fully estimate the amount of nitrogen, phosphorus and potassium nutrients supplied to crops, deduct the amount of nutrients provided by organic fertilizer, and then apply chemical fertilizer supplement, but in the current production practice, vegetable farmers often do not count organic fertilizer nutrients as chemical fertilizer nutrients, resulting in the widespread problem of excessive fertilization. With regard to the appropriate ratio of organic and inorganic: to meet the annual nitrogen supply of vegetable crops as an example, some countries have proposed that the proportion of nitrogen from organic fertilizers accounts for 50% to 60%. The Food and Agriculture Organization of the United Nations has recommended that the ratio of organic nitrogen to inorganic nitrogen is 1 ∶ to determine the application amount of organic fertilizer and chemical fertilizer. Second, according to the quality characteristics of vegetable soil, different kinds of organic fertilizers should be selected, new vegetable fields should choose fermented organic fertilizers with high chemical nutrients and quick effect, such as feces and urine, green manure and cake fertilizer, and old vegetable fields should choose slow-acting organic fertilizers rich in straw and compost fermentation. Some old vegetable fields with serious continuous cropping obstacles have a good effect of straw biological reactor technology, that is, straw is used to improve soil physical properties and supplement sufficient carbon sources. Among the kinds of organic fertilizers, the selection of composting products including manure, urine, straw and solid waste can improve the resistance and root promotion effect of vegetable crops, improve soil pH and soil structure, increase the amount of soil organic matter, passivate the activity of heavy metals in vegetable fields, and reduce the risk of heavy metal pollution. Third, during the application period of organic fertilizer, the general principle is to apply it as base fertilizer or base fertilizer according to the slow effect of organic fertilizer, and apply it before sowing or planting. Do not use it as topdressing, but use chemical fertilizer as topdressing. For this reason, a reasonable proportion of base topdressing should be established, and for high-yield fruit and vegetable crops, the amount of base fertilizer should be reduced and the amount of topdressing should be increased. Finally, the input of fertilizer and water should be controlled in order to reduce the accumulation of nitrogen and phosphorus, leaching and runoff loss of vegetable land, and reduce non-point source pollution. In a word, in the current vegetable production, we should vigorously publicize the knowledge of scientific application of organic fertilizer, popularize the concept of quantitative fertilization, popularize the technology of composting and fermentation of organic materials, and help vegetable farmers to use organic fertilizer innocuously so as to achieve high yield, high quality and safety in vegetable production.