Over 40 percent of China's arable land is degraded, caused by long-term high-intensity overuse
On the 17th, the Ministry of Agriculture released the "Communique on the Quality Grades of National Arable Land," the first time China has graded and classified its arable land.
According to the Communique, the quality grades of the nation's 1.826 billion mu of arable land (land data prior to the Second National Land Survey) are divided from high to low into grades one through ten.
⟦NL> Zeng Yande, Director of the Planting Industry Management Department of the Ministry of Agriculture, explained that in order to ascertain the soil baseline, the Ministry of Agriculture launched a nationwide arable land fertility survey and quality evaluation in 2002. After years of data accumulation, from 2013 to 2014 experts were organized to analyze arable land from multiple aspects including site conditions, tillage-layer physical and chemical properties, soil management, and soil profile characteristics, and to classify the quantity and distribution of arable land in grades one through ten.
According to the Communique, the area of arable land rated grades one through three is 498 million mu, accounting for 27.3% of the total arable land area. This portion of arable land has relatively high inherent fertility and basically no limiting factors, and agricultural production should be carried out in a way that combines use with conservation to ensure that arable land quality rises steadily.
The area of arable land rated grades four through six is 818 million mu, accounting for 44.8% of the total arable land area. The environmental and climatic conditions of this portion of arable land are basically suitable, farmland infrastructure construction has a certain foundation, and its yield-increasing potential is the greatest. It is estimated that by 2020, calculated on the basis of raising the average inherent fertility of arable land by 1 grade, this portion of arable land can achieve an additional comprehensive grain production capacity of more than 160 billion jin.
The area of arable land rated grades seven through ten is 510 million mu, accounting for 27.9% of the total arable land area. This portion of arable land has relatively poor inherent fertility and prominent production limiting factors, is difficult to fundamentally improve in a short time, and should undergo continuous construction of farmland infrastructure and intrinsic arable land quality.
What problems currently exist in China's arable land quality? Researcher Xu Minggang of the Ministry of Agriculture's Expert Steering Group for Arable Land Quality Construction and Management said: "Over these years, China's agricultural production has consistently adhered to a high-input, high-output model, and arable land has been subjected to long-term high-intensity, overloaded use, so arable land quality has shown a 'three large' and 'three low' situation."
Among these, the "three large" refers to a large proportion of medium- and low-yield fields, a large area of degraded arable land quality, and a large area of polluted arable land. According to surveys, among China's existing arable land, medium- and low-yield fields account for 70% of the total arable land area. Extensive farming methods, especially excessive application of chemical fertilizers, have caused the degradation of arable land quality. At present, the degraded area of China's arable land accounts for more than 40% of the total arable land area; soils in the south are acidified, the tillage layer of the North China Plain has become shallower, and the problems of salinization and desertification of arable land in the northwest region are also prominent; the rate of pollution exceeding standards at national arable land soil monitoring points has reached 19.4%; surface water eutrophication in the south and nitrate pollution of groundwater in the north, as well as relatively heavy residual agricultural film in places such as the northwest, are also issues.
The "three low" refers to low organic matter content, low grade of supplementary arable land, and low inherent fertility. For a very long period, the so-called "balance of occupation and compensation" for China's construction land referred only to a balance in quantity. Experts explain that, generally speaking, the fertility of supplementary arable land and occupied arable land also differs by 2 to 3 grades, and 1 grade is equivalent to a production capacity of 100 kg per mu.