How can fertilizer reduction avoid yield loss? Improving fertilizer efficiency is key
——Interview with Yang Fan of the Soil and Fertilizer Technology Division of the National Agricultural Technology Extension Service Center
Since the Ministry of Agriculture launched the action to achieve zero growth in chemical fertilizer use nationwide this year, reducing chemical fertilizer use and curbing the decline in arable land quality have gradually become a general social consensus. The action has progressed relatively smoothly and has achieved the expected goal of reducing chemical fertilizer application without reducing yield. Our reporter interviewed Yang Fan, deputy director of the Soil and Fertilizer Technology Division of the National Agricultural Technology Extension Service Center, on related issues.
Q: At the beginning of the action to achieve zero growth in chemical fertilizer use launched this year, some people worried that reducing chemical fertilizer use would affect grain output. Now that a bumper autumn grain harvest is a foregone conclusion, can this concern be dispelled?
A: After the action to achieve zero growth in chemical fertilizer use was launched, all parts of the country actively promoted various chemical fertilizer reduction techniques. Under these circumstances, our country's summer grain output maintained consecutive increases this year, and a bumper autumn grain harvest became a foregone conclusion, achieving "fertilizer reduction without yield reduction."
National-level data have not yet been compiled, but based on the data we have, under the premise of doing good deep plowing and subsoiling, soil testing and formulated fertilization, and scientific field management, the Huang-Huai-Hai region can still ensure grain output when nitrogen fertilizer is appropriately reduced.
Q: For many years, farmers have formed the belief that "more chemical fertilizer means more grain." Can they accept reduced chemical fertilizer application all at once?
A: Judging from our surveys, farmers' acceptance is relatively high. This is mainly due to the soil testing and formulated fertilization project implemented starting in 2005, which changed farmers' belief that "more chemical fertilizer means more grain," and their awareness of scientific fertilization has also been continuously improving. In addition, in recent years, the prices of phosphate fertilizer and potash fertilizer have fallen, and farmers have begun to reduce nitrogen fertilizer and increase phosphate and potash fertilizer, so the fertilization structure is gradually becoming more reasonable.
It should be noted that for cash horticultural crops, farmers are still very cautious about reducing chemical fertilizer application. This is mainly because such crops have high economic returns, farmers do not care much about input costs, and they worry about yield reduction and impacts on income. This requires agricultural technology extension departments to focus on it and provide more precise technical guidance.
Q: The purpose of the action to achieve zero growth in chemical fertilizer use is not only to emphasize reducing chemical fertilizer use; improving chemical fertilizer use efficiency is also an inherent requirement, right?
A: Emphasizing only the reduction of chemical fertilizer use is one-sided. To ensure that crops do not suffer yield reduction, it is also necessary to improve chemical fertilizer use efficiency. Technically, vigorously promoting soil testing and formulated fertilization, advancing precision fertilization, and changing surface application and broadcast application of chemical fertilizer to mechanical deep application, integrated water and fertilizer application, and foliar spraying can all improve chemical fertilizer use efficiency. In addition, promoting and applying new types of fertilizers, such as slow-release fertilizers and humic acid-containing fertilizers, can also improve chemical fertilizer use efficiency.
Q: What are the difficulties and priorities in further promoting the action to achieve zero growth in chemical fertilizer use?
A: The technical path designed by the action plan for zero growth in chemical fertilizer use is "precision, adjustment, improvement, substitution," namely advancing precision fertilization, adjusting the structure of chemical fertilizer use, improving fertilization methods, and replacing chemical fertilizer with organic fertilizer. Personally, I feel that the most difficult part is replacing chemical fertilizer with organic fertilizer, and it is also the most important. Making good use of organic fertilizer can, first, allow the nutrients in organic fertilizer to replace part of the nutrients in chemical fertilizer and reduce chemical fertilizer use; second, increase soil organic matter content and improve soil microbial activity and soil water- and fertilizer-retention performance, thereby improving arable land quality; third, solve the environmental pollution problems caused by discarded livestock and poultry manure and straw burning. It can be said to achieve three goals at once.
However, given our country's current actual situation, increasing organic fertilizer application faces great difficulties. The main issues are that commercial organic fertilizer is relatively expensive and has low available nutrient content. Considering only the point of organic fertilizer nutrients replacing chemical fertilizer nutrients, it is difficult for farmers to accept applying organic fertilizer to grain crops. Farmers composting organic fertilizer themselves face problems such as insufficient labor, lack of fertilizer sources, and limited space. How to solve these issues is something we are also trying in many ways, such as adopting the method of government purchase of socialized services.