Soil nutrient status is an important indicator of farmland soil fertility. The fixed monitoring of farmland fertilizer input and soil nutrient levels can not only be used to guide the application of fertilizers in the surrounding farmland, but also the results of long-term monitoring can understand the trend of soil fertility evolution, analyze the problems of local farmland fertilization, and provide a basis for macroeconomic decision-making. The original soil fertility station of the Ministry of Agriculture began to monitor the country’s farmland fertility since 1985. By the end of 1997, there were 147 state-level monitoring effective points for more than three consecutive years, distributed in 80 counties in 16 provinces, autonomous regions, and municipalities, involving 16 soils. class. According to the cooked system, there are 34 in a mature area, 84 in the second mature area, and 29 in the Sanshen area. This paper analyzes and discusses the nutrient changes and nutrient input of arable land in China based on the monitoring results over 10 years, and puts forward suggestions for fertilizer application in the future.
The relationship between chemical fertilizer application and grain growth in China is a matter of common concern. In recent years, people have noticed that the increase in fertilizer consumption in China is much faster than the increase in grain production. The reason why it is still difficult to answer. The main reason is that China's current statistics on fertilizer consumption are generally total only, and there is no distribution of various crops. Therefore, it is difficult to make reliable statistics on the application of chemical fertilizers on food crops and their growth over the years. Although there are only 147 soil monitoring sites in the country, they cover a wide range of areas and have good representativeness. Most of them are grain fields. Most of the monitoring sites are equipped with soil nutrient detection instruments and other soil nutrient detection instruments, and fertilization in conventional fertilization treatment areas is provided. The situation represents the general level of the local area. Therefore, the changes in fertilization can reflect the changes in fertilization of food crops to some extent. The monitoring results show that the fertilizer application rate per unit area of ​​grain crops has been growing slowly in recent decades, which means that the proportion of increased chemical fertilizers used in food production is relatively small, which is consistent with some scholars' estimates.
The application of organic manure is an effective measure for fertilizing the soil. From the perspective of fertilization at the monitoring sites, the input of organic fertilizer has gradually decreased. Although the results have not shown a significant reduction in soil organic matter and available nitrogen content, this may be a global issue in the long run and will affect the stability of China's agricultural production.
The NPK nutrient input-output balance determines the rise and fall of soil nutrient content. Nitrogen has a tendency to increase after being applied to the soil. Simple calculation of the balance of payments will hardly reflect the increase and decrease of soil nitrogen content. The increase in phosphorus surplus has been reflected in the increase of available phosphorus content; the deficit of potassium is increasing in the north. While the south is slowing down, this is basically consistent with the change of soil available potassium content. Organic manure is an important source of soil potassium, and the reduction of organic manure consumption year by year will exacerbate the deficit of potassium. This is also an important reason for the importance of organic manure application.
For these situations, the following issues need to be noted in the future management and use of fertilizers:
1. The deficiency of potassium is a serious problem that is almost national, and it is imperative to pay attention to the study of potassium and the application of potash.
2. The reduction of organic fertilizer application did not result in a decrease in soil organic matter, but the effects of other characteristics of soil fertility, such as soil structure, soil microflora, and soil microecological environment, need further study.
3. The focus of farmers' fertilization has shifted from grain crops in Daejeon to cash crops such as fruit trees and vegetables. While paying attention to the research and application and promotion of field crop fertilization technology, attention should be paid to the research and application of fertilization techniques for economic crops such as fruit trees and vegetables.
4. Over-application of nitrogen fertilizer has attracted attention in some areas. From the monitoring results, it is necessary to study and attract sufficient attention to the possible effects of excessive application of phosphate fertilizer and accumulation of phosphorus in many areas.
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