What are the technical paths for reducing chemical fertilizer use and increasing its efficiency?
On March 17 this year, the Ministry of Agriculture proposed striving to achieve zero growth in the use of chemical fertilizers and pesticides on major crops by 2020. The key to achieving this goal is to grasp well the "precision, adjustment, improvement and substitution": advancing precision fertilization, adjusting the structure of chemical fertilizer application, improving fertilization methods, and replacing chemical fertilizers with organic fertilizers. Based on the above requirements and practical experience, the author has organized and summarized the technologies for reducing chemical fertilizer use and increasing its efficiency, for the reference of the broad community of farmers.
Soil testing and formula fertilization technology
Soil testing and formula fertilization is based on the fertilizer requirements of crops, the fertilizer-supplying performance of the soil and fertilizer effects, and, on the basis of rational application of organic fertilizers, selects the application quantity, fertilization period and application methods of fertilizers such as nitrogen, phosphorus, potassium and medium and trace elements. Soil testing and formula fertilization technology supplements the nutrient elements required by crops in a targeted manner: whatever element the crop lacks, that element is supplemented, and however much is needed, that much is supplied, achieving balanced supply of various nutrients, meeting the needs of crops, and thereby achieving the goals of increasing crop yields, reducing agricultural production costs and protecting the agricultural ecological environment.
Mechanized deep fertilization technology
Mechanized deep fertilization technology mainly refers to the use of agricultural machinery during plowing, sowing and the mid-growth stage of crops to apply chemical fertilizers below the soil surface to a certain depth according to the type, quantity and fertilizer position effects required by agronomic practices. This mainly includes: deep application of base fertilizer, deep application of seed fertilizer (also called simultaneous sowing and fertilizing), and deep application of topdressing. Mechanized deep application can reduce chemical fertilizer losses, improve chemical fertilizer use efficiency, save costs and increase benefits.
Water and fertilizer integration technology
Water and fertilizer integration technology is a new agricultural technology that combines fertilization with irrigation. Through a pressure pipeline system and emitters installed on the terminal pipelines, it delivers fertilizer solution uniformly and accurately at a relatively small flow rate directly to the soil surface near the crop roots or into the soil layer, as an irrigation and fertilization method, and can supply water and nutrients directly to crops in fixed amounts and at fixed times according to crop growth needs. Its characteristic is that it can precisely control the amount of irrigation water and fertilizer, significantly improving water and fertilizer use efficiency. In terms of yield increase and efficiency improvement, compared with traditional technology, vegetables save 30%-35% of water and 40%-45% of fertilizer; orchards save 40% of water and 30% of fertilizer; vegetable yields increase by 15%-22%, and fruit yields increase by 9%-15%.
Mixed application of farmyard manure and chemical fertilizers
Organic fertilizers have many types, wide sources, are easy to accumulate and make, have low cost and are simple to apply, and are an important technology for developing high-quality, high-efficiency and low-consumption agriculture. Fully decomposed farmyard manure has relatively complete nutrient content, and its fertilizer effect is lasting and stable. Persisting in the mixed application of chemical fertilizers and farmyard manure can, first, improve the physical and chemical properties of the soil and enhance soil fertility; second, allow slow-release and quick-acting fertilizers to complement each other's advantages; third, reduce the volatilization and loss of chemical fertilizers, enhance fertilizer retention performance, and relatively quickly improve the fertilizer-supplying capacity; and fourth, improve crop stress resistance and quality, and have a significant effect on reducing environmental pollution.
Using straw decomposition agents to improve straw return technology
Straw decomposition agents can quickly decompose organic waste such as straw, turn the organic matter and elements such as phosphorus and potassium contained in straw into nutrients needed for plant growth, and produce large amounts of beneficial microorganisms, increase soil organic matter, reduce the amount of chemical fertilizer used, enhance plant stress resistance, improve crop quality, and realize sustainable agricultural development. Returning 200 kg of straw per mu to the field can reduce the application of phosphorus fertilizer and potassium fertilizer by 20%, that is, reduce the application of potassium chloride by 2 kg and calcium superphosphate by 5 kg per mu, saving 15 yuan in chemical fertilizer input per mu. In the early stage of straw return, a certain amount of nitrogen is consumed, so the amount of nitrogen fertilizer applied in the early stage should be appropriately increased and the amount of nitrogen fertilizer applied in the later stage should be reduced.
Making good use of biogas residue and biogas slurry to realize ecological circular agriculture
Biogas slurry and biogas residue are collectively called biogas fertilizer, and are the product of anaerobic fermentation of biomass in biogas digesters. Biogas slurry contains abundant nitrogen, phosphorus, potassium, sodium and tungsten nutrients. Biogas residue is composed of some undecomposed raw materials and newly generated microbial cells. Biogas residue contains relatively large amounts of humic acid, has an improving effect on soil, and can increase soil organic matter. Based on farmers' land resources and linked by new and efficient biogas, a benign agricultural circular system is formed in which agriculture promotes animal husbandry, biogas promotes agriculture, and supporting development occurs, which is conducive to improving the quality of fruits and vegetables, improving the comprehensive benefits of agricultural production, and realizing efficient use of agricultural resources.
Improving soil structure and raising soil fertility
Methods of soil improvement mainly include deep soil plowing, increasing application of organic materials, mulching cultivation, promoting microbial proliferation, and promoting earthworm proliferation. By improving the soil, the physical and chemical properties of the soil can be improved, soil microbial activity can be enhanced, and soil fertility and fertilizer use efficiency can be increased by more than 5%. Farmers should be guided to improve farming methods and implement rational crop rotation, intercropping and relay intercropping; implement rotation of paddy and dryland crops and rotation of grain and vegetables; carry out rotation, intercropping and relay intercropping of different types of crops and varieties of the same crop type from different families; and through plants' own regulation of soil nutrient components, improve soil fertility and reduce the amount of chemical fertilizer used.
Promoting new fertilization technologies
First, advocate the application of high-content multi-element compound fertilizers and reduce the application of low-content compound mixed fertilizers; second, actively trial high-energy organic-inorganic compound fertilizers; third, promote organic-inorganic compound mixed fertilizers; fourth, apply fertilizers that also serve as pesticides and are combined with high-content beneficial microorganisms; fifth, accelerate the application of new fertilizers such as high-efficiency slow-release fertilizers, water-soluble fertilizers, biological fertilizers and soil conditioners; sixth, apply chemical fertilizers precisely and avoid excessive use; and seventh, in places where conditions permit, use drip irrigation to apply liquid fertilizers evenly.