The present situation of cultivated land quality in China is worrying about the lack of basic soil capacity of cultivated land.

Cultivated land is the foundation of agriculture. According to the investigation conducted by China Economic Times reporters for more than half a month, at present, there are both quantity and quality problems in cultivated land in China. First of all, in terms of quantity, China's cultivated area is 1.826 billion mu, less than 1.4 mu per capita, only 40% of the world average. Secondly, from the quality point of view, cultivated land load increases year by year, regional degradation problem is increasingly serious. Moreover, with the economic and social development, especially the acceleration of industrialization and urbanization, while the trend of reducing the number of cultivated land is difficult to reverse, the problem of cultivated land quality will also become increasingly prominent.

Growing degradation of cultivated land

"The land is getting less and less, and the fields are getting more and more difficult to plant. If it weren't for the fertilizer, I'm afraid we wouldn't have been able to keep our jobs." In grass-roots interviews, many farmers and agricultural workers told China Economic Times reporters.

According to the statistics of the Ministry of Agriculture, the degraded cultivated land area caused by soil erosion, impoverishment, secondary salinization and acidification accounts for more than 40% of the total area in China.

"The thickness of black soil layer in Northeast China has decreased from 80- 100cm at the initial stage of reclamation to 20- 30cm. The average organic matter content of cultivated soil in black soil area is 26.7g/kg, which is 12g/kg lower than that 30 years ago, with a decrease of 31%; The thickness of cultivated layer in North China Plain is 15- 19cm, 3- 7cm shallower than the suitable 22cm; Soil acidification in the south and salinization in the northwest are still prominent." In a material provided by the Ministry of Agriculture to our reporter, this is stated.

According to the data of soil testing and formula fertilization of the Ministry of Agriculture, the proportion of soil PH value less than 6.5 in 14 provinces (autonomous regions and municipalities) in southern China has expanded from 52% 30 years ago to 65%, the proportion of soil PH value less than 5.5 has expanded from 20% to 40%, and the proportion of soil PH value less than 4.5 has expanded from 1% to 4%. The salinization area of cultivated land in Northwest China is 300 million mu, accounting for 60% of the whole country. Among them, the secondary salinization area of cultivated land is 21 million mu, accounting for 70% of the whole country.

Insufficient basic soil fertility of cultivated land

According to Xu Minggang, a researcher at the Institute of Agricultural Resources and Agricultural Regionalization of the Chinese Academy of Agricultural Sciences, 70%-80% of grain output in European and American countries depends on basic soil fertility and 20%-30% depends on water and fertilizer input, while the contribution rate of cultivated land basic soil fertility to grain output in China is only 50%, which is 20- 30% lower than that of developed countries such as Europe and America.

Xu Minggang said that long-term unreasonable application of chemical fertilizers not only leads to imbalance of soil nutrients, decline of soil fertility and organic matter, but also heavy metals contained in some fertilizers are threatening human safety.

Data provided to this newspaper by the Ministry of Agriculture show that the average content of available phosphorus in China's soil is 23.1 mg/kg, which is nearly three times higher than that of the second soil survey.

In addition, Shen Qirong, vice president of Nanjing Agricultural University, found that the cultivated soil biome is also decreasing.

"Thirty years ago, there were an average of 3,000 - 5,000 beneficial nematodes per kilogram of soil, but now there are only 500. There used to be 10 grams of earthworms per kilogram of soil, but now there are almost no earthworms in the fields without organic fertilizer." Shen Qirong said.

"If it weren't for chemical fertilizer, the basic soil fertility of cultivated land in our country is not enough to support high grain yield year after year." Peng Shiqi, chief expert of the National Agricultural Technology Extension Service Center of the Ministry of Agriculture, said in an interview with China Economic Times.

The problem of cultivated land pollution is prominent

In addition, data from the environmental department show that at present, more than 10% of the country's cultivated area is polluted by heavy metals to varying degrees. Among them, 30 million mu of farmland polluted by Kuangqu, 75 million mu of farmland polluted by oil, 750,000 mu of farmland polluted by solid waste accumulation, nearly 150 million mu of "industrial three wastes" pollution and nearly 50 million mu of farmland polluted by sewage irrigation.

A survey shows that nearly 40% of farmland and vegetable soil in the Pearl River Delta has been polluted by heavy metals, and 10% of them are seriously exceeding the standard. The "white pollution" of farmland is also gradually aggravated. Every year, 500,000 tons of agricultural film remains in cultivated land, forming a water-impermeable and airtight refractory layer in the soil layer of 15-20 cm, posing a great threat to the quality of cultivated land.

"Soil pollution has expanded from single inorganic or organic pollution to multiple and compound pollution, with diversified pollution types, diversified pollution routes and complicated pollution causes." An industry expert who declined to be named told the China Economic Times reporter.