The achievements of this project belong to agricultural science and technology/soil and fertilizer/soil pollution control technology. Farmland soil quality is directly related to the yield and quality safety of agricultural products. The "National Soil Pollution Survey Bulletin" shows that the rate of over-standard soil points in cultivated land in my country is 19.4%, and the situation of heavy metal pollution in farmland is severe. However, most mature remediation technologies suitable for site pollution cannot be applied to farmland soil remediation due to their high cost. In view of the current outstanding problems of lack of low-cost and efficient remediation technology for farmland soil and low bioremediation efficiency, the project is based on the needs of the country and society, aims at green, efficient and safe utilization, and has achieved achievements in the theoretical aspects of chemical passivation and bioremediation mechanisms of farmland soil. A series of breakthroughs have been built and promoted and applied a chemical-bioremediation technology system. The innovative results are as follows:

1)The control mechanism of chemical passivation remediation technology has been explored, and new high-efficiency passivators have been developed: the process and mechanism of organic fertilizers, sulfur fertilizers, etc. regulating the absorption and accumulation of heavy metals in crops has been explored, and the resistance of organic fertilizers and sulfur fertilizers on the absorption and accumulation of heavy metals in rice has been confirmed. control effect; A highly efficient passivator that can be used to repair typical heavy metals in farmland soil has been developed. The accumulation of heavy metals in passivator plants has been reduced by more than 50%. Field demonstration applications have shown that the application of passivator can simultaneously increase crop production. It is proposed that the application of high-efficiency passivator is an effective way to achieve the safe utilization of heavy metals polluted farmland.

2) A new bioremediation technology was created: plants with good potential for remediation of heavy metals were screened out, and nitrogen and cutting could enhance the extraction efficiency of heavy metals in Iris plants were proposed. Highly efficient Cr(VI) reducing bacteria were screened. Among them, two strains with better reducing effects were mixed application of bacteria Wn-1 and Ws-2, which reduced Cr(VI) in contaminated soil by up to 75.3%; A vector for plants to enhance their repair capabilities was created, independent intellectual property rights of heavy metal tolerance genes TtHMBP, MerT, and TrCRD2S were obtained, plants 'ability to resist heavy metals was enhanced, and an efficient genetic transformation system was successfully established; target genes for plant repair were proposed, and it was found that Iris metallothionein genes IlMT2a, IlMT2b, and cysteine enrichment gene llCDT1 can be used as target genes for soil Cu/Cd plant repair, providing theoretical support for improving bioremediation efficiency.

3) A chemical-biological joint remediation technology system has been established and promoted and applied: Based on the activation of soil organic chelating agents and the extraction of heavy metals from enriched plants, a chemical-plant joint remediation technology system has been initially established; Based on the distribution characteristics of crop roots and soil layers and cumulative differences in heavy metal absorption, a high-efficiency plant extraction technology that enriches heavy metals between plants/interplants is established, and combined with the application of high-efficiency passivators to build and apply a chemical-biological joint remediation technology system.

The project enterprises have demonstrated and promoted an area of 330,000 acres in moderately and mildly polluted rice fields in Hunan, Jiangsu, Shanghai and other provinces and cities, with a cumulative output value of 118 million yuan. The overall technology of the project can realize production and restoration of heavy metal-contaminated farmland. The project published 17 papers, including 9 SCI papers and 8 authorized invention patents. The direct economic benefits of the project are 118 million yuan; the cumulative benefits generated by application and promotion projects of other cooperative units are 766.4 million yuan. The project has significant economic benefits and significant social benefits. The project technology leads the farmland soil remediation industry to develop in an efficient, ecological and sustainable direction.