"New Agricultural subsidy" helps to solve the soil crisis.

According to the news from the Fifth China Environmental Restoration and Development Strategy Forum held recently, the draft "soil pollution Prevention and Control Law" drafted by the Environmental assets Supervision and Administration Committee of the National people's Congress has formally solicited public opinions. According to the plan, the proposed draft of the law will be submitted to the standing Committee of the National people's Congress for deliberation next year and incorporated into the legislative plan.

At present, in the "three major battles" for the prevention and control of air, water and soil pollution in China, only the legislation on the prevention and control of soil pollution is absent. For many years, there are no legal norms for the prevention and control of soil pollution, there are not only the lack of "economic measures" at the practical level, but also differences related to specific treatment measures. All these reflect the complexity and arduousness of soil pollution prevention and control.

China has a large population and little land, and the problem of grain production is still prominent. A person engaged in grain trade in Guangzhou once asked the author for help: her rice, which was sold to customers and sold well, was complained about excessive cadmium. How should such soil be treated? By testing some soil samples she collected, the author found that the total amount of cadmium in the soil was only 0.2 mg / kg, which was lower than the limit of the current soil environmental quality standard in China (0.3 mg / kg). However, due to the low soil pH value, less than 5.0, the cadmium in rice exceeds the standard by more than twice. Since then, the author has come across many such examples one after another. Some farmers and organic farmers are full of confusion. How can the rice under hard work exceed the standard of cadmium in the arable land far away from pollution sources?

The emergence of this strange phenomenon is undoubtedly related to the great impact of excessive application of fertilizers and pesticides on the soil ecosystem in China. The main harm caused by the excessive use of chemical fertilizers and pesticides is the rapid acidification of soil and the weakening or even loss of the function of soil ecosystem. According to the research results published in Science in 2010 by Zhang Fusuo et al., since the 1980s, in the past 30 years, the pH of soil in China has decreased by 0.13-0.80 units, especially in agro-ecosystem. 0.80 units means that the acidity of the soil has increased as much as six times.

As the article points out, if this range is allowed to be accomplished by nature, it will take tens of thousands of years. It can be seen that the massive application of chemical fertilizer has a great impact on soil properties and soil ecological function. For some heavy application areas such as the Yangtze River Delta and the Pearl River Delta, the impact strength is even greater.

As a product of parent material, climate, biology, topography and time, soil is an ecosystem with high vitality. There are more creatures in a handful of soil than the population of the earth. In principle, there should be 10 trillion bacteria, 3000 earthworms, snails and a vertebrate in 1 square meter of soil. However, under the condition of high fertilizer and high medicine, it can be seen that the organisms have been lost, and the organisms invisible to the naked eye are also deeply impacted, and the normal biological functions such as soil nitrogen fixation, phosphorus release and potassium release can not be brought into full play. In addition, due to the destruction of the soil food web chain, some soil organisms are "dominant", resulting in unhealthy crops, such as root rot, root-knot nematode and so on.

Soil acidification directly leads to the release of heavy metals in soil minerals, the activation of heavy metals adsorbed on soil clay, and the inability of soil to "aging" foreign heavy metals, which leads to the improvement of the availability of heavy metals in soil. grain production exceeded the standard. Especially for cadmium, a harmful heavy metal that is easy to migrate in the soil-plant system, the activation effect of cadmium in soil acidification is more obvious, resulting in the establishment of the most stringent soil environmental quality standards in the world, but will still produce over-standard grain.

The "Reform Plan for establishing a Green Ecology-oriented Agricultural subsidy system" adopted on November 1 proposes to highlight the green ecological orientation, speed up the implementation of relevant agricultural subsidy policy reform, and shift the policy goal from quantitative growth to quantitative and qualitative ecology. The establishment of a green ecology-oriented reform scheme of agricultural subsidy system has undoubtedly injected a corrective driving force into agricultural production caught in a vicious circle. it is also a good institutional guide to restore unhealthy soil caused by excessive application of chemical fertilizers and pesticides.

China began to carry out all-round agricultural subsidies in 2004, mainly in the aspects of chemical fertilizer, agricultural machinery and farmland infrastructure. These subsidies undoubtedly play an important role in ensuring the steady increase of grain production and realizing the "twelve consecutive increases" of grain in our country. However, these measures have also promoted the excessive application of chemical fertilizers and pesticides, resulting in the fact that less than 10% of the world's land uses fertilizers accounting for 1% of the world's total; the average amount of chemical fertilizer application is 463 kg / ha, 3.5 times the world average of 131 kg / ha, and 1.93 times the usual warning line of 225 kg / ha.

Among the many soil-forming factors, the increase of human factors in agricultural soil has become the strongest influencing factor. It can be said that human factors (fertilization, pesticide application) greatly changed the soil biological factors in a short time, resulting in unhealthy soil. Therefore, it is certain that the establishment of a green ecology-oriented reform programme of agricultural subsidy system will contribute to soil health.

(author Chen Nengchang is a researcher of Guangdong Institute of Ecological and Environmental Technology)