With the "new nemesis", the cadmium reduction rate of soil cadmium pollution can reach 85%.

Since the "cadmium rice" incident, Hunan has been constantly seeking and exploring effective technologies and methods to control cadmium pollution in soil. Many domestic scientific research institutes and related enterprises have also used Hunan as a test base to verify the effectiveness of products and technologies. A few days ago, the reporter first discovered "cadmium rice" in Hunan You County, the scene witnessed a "double salt chelation passivation technology" soil conditioner to control cadmium pollution effect.

October 15, in You County Fengtai rice planting cooperative more than 100 acres of "Hongling" brand soil conditioner improvement, repair soil demonstration film, the reporter saw, full ears of rice bent waist, the field a pleasant harvest scene. The expert group sampled and tested at many points on site, and the results showed that the cadmium content of rice samples was below 0.05mg/kg, far lower than the national standard of 0.2mg/kg. The expert group also sent rice samples to a third-party testing agency. The test report two weeks later showed that the cadmium content was 0.013~0.028mg/kg, which confirmed the cadmium reduction effect of this soil conditioner again.

"The original background cadmium content of the soil without remediation is 0.75mg/kg. From the current detection results, the cadmium reduction rate can reach more than 85%, and the effect is ideal." Lei Ming, a member of the expert group for on-site evaluation and professor of Zihuan College of Hunan Agricultural University, said.

Why is this soil conditioner effective in reducing cadmium levels? Lei Zhigang, chief expert of Hunan Hongling Agricultural Science and Technology Co., Ltd., told reporters that at present, there are "electrolysis methods","leaching methods" and "soil replacement methods" for acidic heavy metal polluted land in the south, but there are problems such as high cost and difficulty in operation. Our technology does not have to remove cadmium, but uses the original layered silicate and pyrophosphate "double salt chelation passivation technology" to fix cadmium in the soil so that it cannot be freely transmitted to rice. the problem of excessive cadmium in rice can be solved. This technology is not only effective for cadmium reduction, but also for heavy metals other than mercury.

Luo Zanxing, chairman of Hunan Hongling Agricultural Science and Technology Co., Ltd., introduced that the company has developed a series of comprehensive soil heavy metal treatment technologies with completely independent intellectual property rights and high-quality, high-yield and low-consumption rice planting technologies for several years, forming a three-dimensional prevention and control system for comprehensive treatment of heavy metals of "double salt chelation","in-situ separation","plant retardation" and "comprehensive metabolism", which has been tested in 69 experimental demonstration areas in 15 provinces and cities successively, and the effects have reached or exceeded the expected standards. In 2016, Hongling Company successively participated in the fifth phase of super rice 16 tons per hectare and the stability test of soil conditioner in different places of the Ministry of Agriculture. The soil background value was between 0.6~10mg/kg. Applying 200~600 kg of this technical product per mu could not only produce qualified agricultural products (cadmium content below 0.1 mg/kg), but also increase production by 10%~30%.

Luo Ximing, senior agronomist of Zhuzhou City Agricultural Committee, told reporters that at present, the methods to control soil cadmium pollution mainly include selecting low cadmium absorption varieties, flooding irrigation, adjusting pH value, deep tillage, using soil conditioners, using foliar resistance control agents, returning green manure to fields and other measures, but there are some agronomic measures farmers have not been able to adopt, so the government is also seeking easy to promote implementation, can complement the technology and products.

So is the cost of adopting this set of technology products high? In this regard, Luo Zanxing said, we are not a simple product, but a complete set of soil testing and improvement restoration programs. The state has soil improvement subsidies for heavy metal over-standard plots. In Hunan, the government grants 5000 yuan per mu for the restoration of problematic plots, and 15,000 yuan per mu in Shaoguan, Guangdong. Taking You County of Hunan Province as an example, we repaired 104 mu of land seriously exceeding cadmium standard, with a total investment of about 500,000 yuan, and the effect of one investment can reach more than 10 years.

The reporter learned that for the barrier soil in different areas, Hongling Company will combine experts and intelligent systems to scientifically detect the background value of the soil, implement the "soil testing formula", and then apply soil conditioners and scientific management methods to effectively improve and repair the soil. For healthy soil up to standard, crop waste can be returned to the field healthily through concentrated fertilizer production of straw, organic residues, livestock manure, etc., so as to reduce the application amount of chemical fertilizer and form a virtuous circle from soil improvement to crop residue treatment and crop safety production. reporter Wang tengfei