The key to zero growth in chemical fertilizer use is treating both the symptoms and root causes of cultivated land
“To achieve zero growth in chemical fertilizer use, it is still necessary to improve the fertilization structure. This can maintain stable and continuously growing agricultural productivity, stable and sustained soil fertility, a healthy and balanced ecological environment, and the sustainable use of resources and the environment.” Zhang Shuqing, director of the Industrial Extension Office of the Fertilizer Institute of the Chinese Academy of Agricultural Sciences, said this in a recent interview with a reporter.
It is understood that excessive use of chemical fertilizers first causes a decline in the quality of cultivated soil, pollution from heavy metals, pesticides and inferior chemical fertilizers; second, soil drought, desertification, salinization and acidification are serious, and there is a general lack of organic matter, medium and trace elements; third, continuous cropping of the same crops leads to worsened soil-borne diseases, decreased soil fertility, poor microbial activity and reduced productivity.
The effect of chemical fertilizer application on increasing yields has reached a “ceiling”
Meng Deli, a farmer from Huxin Village, Shuanghe Township, Keshan County, Heilongjiang, planted 1200 mu of land this year. Last year, most of it was soybeans; this year, in order to increase output, he switched to planting 700 mu of corn. Talking about chemical fertilizer input, he said: “In the past two years, chemical fertilizer input has kept increasing, and the amount of chemical fertilizer input per mu has had to increase by about 10 jin every year, otherwise I feel that grain output declines.”
When farming, farmers seem to have fallen into a prisoner's dilemma over whether to use less or more chemical fertilizer: using less reduces output, while using more does not raise output either.
Relevant experts analyzed that there are four major problems in chemical fertilizer application in China at present: first, the average application rate per mu is on the high side. China's average chemical fertilizer use per mu of crops is 21.9 kg, far higher than the world average (8 kg per mu), 2.6 times that of the United States and 2.5 times that of the European Union; second, unbalanced fertilization is prominent, with relatively high application rates in economically developed eastern regions, the lower reaches of the Yangtze River and suburban areas, and excessive fertilization is fairly common in higher-value economic and horticultural crops such as vegetables and fruit trees; third, the utilization rate of organic fertilizer resources is low. At present, the total nutrients in China's organic fertilizer resources are about more than 70 million tons, with an actual utilization rate of less than 40%; fourth, the fertilization structure is unbalanced, traditional manual fertilization methods still dominate, broadcasting and surface application of chemical fertilizers are fairly common, and mechanical fertilization accounts for only about 30% of the planting area of major crops.
Various experimental data show that the marginal benefit of chemical fertilizer input in China has declined markedly. Taking nitrogen fertilizer as an example, from 1998 to 2013, China's nitrogen fertilizer application rate for wheat increased by nearly 200%, but the yield level rose by only 50%.
This shows that chemical fertilizer application has reached a “ceiling”, and using more fertilizer has only a limited effect on increasing grain output.
Reducing chemical fertilizer requires building a green fertilizer system
In order to reduce chemical fertilizer use, relevant agricultural departments have already taken action, such as implementing soil testing and formulated fertilization projects, mechanized deep plowing, and integrated water and fertilizer measures.
Zhang Shuqing said: “We can learn from successful foreign experience —— build China's green fertilizer system. First, we must achieve green and high-efficiency chemical fertilizer products and realize increased efficiency and reduced application of chemical fertilizers; second, we must build the concept of integrated planting and breeding and realize reduced application through substitution of chemical fertilizers with organic fertilizers; third, we must popularize precision fertilization technology and mechanized and intelligent fertilization to achieve precise fertilizer input; finally, management must be legalized, gradually putting fertilizer input management on a legal track, and encourage farmers to use new environmentally friendly planting technologies by establishing scientific subsidy policies.”
⟦NL> For example, in recent years China's rapidly developing new fertilizers such as slow and controlled release fertilizers, water-soluble fertilizers and value-added fertilizers have met the needs of green environmental protection, safety and high efficiency. Taking value-added fertilizers as an example, these are fertilizer modification and efficiency-enhancing products produced by adding natural active substances such as alginic acids, humic acids and amino acids during fertilizer production. Efficiency enhancers such as alginic acids, humic acids and amino acids are all natural substances or plant-derived, can improve fertilizer use efficiency, and are environmentally friendly and safe.