China's Arable Land Quality Is Worrying, with Insufficient Inherent Soil Fertility

Arable land is the foundation of agriculture. Judging from a survey conducted by a China Economic Times reporter over more than half a month, at present, China's arable land has both a quantity problem and a quality problem. First, in terms of quantity, China's arable land area is 1.826 billion mu, less than 1.4 mu per capita, only 40% of the world average. Second, in terms of quality, the burden on arable land is increasing year by year, and regional degradation problems are becoming increasingly serious. Moreover, with economic and social development, especially the accelerated pace of industrialization and urbanization, while the trend of declining arable land quantity is difficult to reverse, the quality problem of arable land will also become increasingly prominent.

Arable Land Degradation Is Becoming Increasingly Serious

“There is less and less land, and the fields are getting harder and harder to farm. If it were not for chemical fertilizers holding things up, I am afraid our rice bowl would not be secure either.” During interviews at the grassroots level, many farmers and agricultural workers told China Economic Times reporters.

According to statistics from the Ministry of Agriculture, nationwide, arable land degradation caused by soil erosion, impoverishment, secondary salinization, and acidification has already accounted for more than 40% of the total area.

“The thickness of the black soil layer in Northeast China has dropped from 80—100 cm in the early period of reclamation to 20—30 cm. The average organic matter content of arable soil in the black soil region is 26.7 g/kg, a decrease of 12 g/kg compared with 30 years ago, a drop of as much as 31%; the plow layer thickness of the North China Plain is 15—19 cm, 3—7 cm shallower than the suitable 22 cm; soil acidification in the South and salinization in the Northwest remain prominent.” This is how it was stated in a document provided to our reporter by the Ministry of Agriculture.

Data from the Ministry of Agriculture's soil testing and formulated fertilization program show that in 14 provinces (autonomous regions and municipalities) in the South, the proportion of soil with a pH value below 6.5 expanded from 52% 30 years ago to 65%, the proportion with a pH value below 5.5 expanded from 20% to 40%, and the proportion with a pH value below 4.5 expanded from 1% to 4%. In the Northwest region, the salinized arable land area is 300 million mu, accounting for 60% of the national total. Among this, the area of secondary salinization of arable land is 21 million mu, accounting for 70% of the national total.

Insufficient Inherent Soil Fertility of Arable Land

According to Xu Minggang, a researcher at the Institute of Agricultural Resources and Regional Planning of the Chinese Academy of Agricultural Sciences, in European and American countries, 70%—80% of grain output depends on inherent soil fertility, and 20%—30% depends on water and fertilizer inputs, whereas in China the contribution rate of inherent soil fertility of arable land to grain output is only 50%, 20—30 percentage points lower than that of developed countries such as those in Europe and America.

Xu Minggang said that the long-term irrational application of chemical fertilizers not only leads to imbalances in soil nutrients and declines in soil fertility and organic matter, but also that heavy metals contained in certain chemical fertilizers are threatening human safety.

Data provided to our newspaper by the Ministry of Agriculture show that at present the average available phosphorus content in China's soil is 23.1 mg/kg, an increase of nearly 3 times compared with the Second National Soil Survey.

In addition, research by Shen Qirong, vice president of Nanjing Agricultural University, found that the soil biome of arable land is also continuously decreasing.

“Thirty years ago, there were on average 3000—5000 beneficial nematodes per kilogram of soil, but now there are only 500. Previously there were 10 grams of earthworms per kilogram of soil, but now in fields where organic fertilizer is not applied, earthworms are almost impossible to find.” Shen Qirong said.

“If it were not for chemical fertilizers holding things up, the inherent soil fertility of China's arable land would not be enough to support consecutive years of high grain yields.” Peng Shiqi, chief expert of the National Agricultural Technology Extension Service Center of the Ministry of Agriculture, said this when interviewed by a China Economic Times reporter.

The Problem of Arable Land Pollution Is Prominent

In addition, data from environmental departments show that at present more than 10% of the national arable land area is affected by heavy metal pollution to varying degrees. Among this, arable land polluted by mining areas is 30 million mu, arable land polluted by oil is about 75 million mu, pollution from solid waste dumping is about 750,000 mu, pollution from the “three industrial wastes” is nearly 150 million mu, and farmland irrigated with sewage is nearly 50 million mu.

Some surveys show that nearly 40% of farmland and vegetable plot soil in the Pearl River Delta has been polluted by heavy metals, and 10% of that exceeds the standard seriously. “White pollution” in farmland is also gradually worsening. Every year, 500,000 tons of agricultural film remain in arable land, forming a water-impermeable and air-impermeable hard-to-degrade layer in the 15—20 cm soil layer, posing a huge threat to arable land quality.

“Soil pollution has expanded from the original single inorganic or organic pollution to multiple and compound pollution, with diversified pollution types, diversified pollution pathways, and increasingly complex pollution causes.” An industry expert who was unwilling to be named told a China Economic Times reporter.