Recently, the Innovation Team of Fertilizer and Fertilization Technology of the Institute of Agricultural Resources and Regional Planning (IARRP) of the Chinese Academy of Agricultural Sciences (CAAS) has discovered that mixed-planting different green manures increased the iron plaque content in rice root and modified the soil dissolved organic matter (DOM), leading to controlling the absorption of cadmium (Cd) in rice. The findings were published in the journal "Environmental Research" on March 14, 2024.

Mixed-planting different green manure species is a common technique to enhance the effect of green manures in paddy fields. However, it has not been clear whether mixed-planting green manures is more effective in controlling Cd compared to single planting.

Cao Weidong, the corresponding author of the paper and the professor at the IARRP, said, "The study found that compared to winter fallow conditions, both single planting and mixed-planting of green manures significantly reduced the Cd content in different parts of rice. Specifically, the Cd content in rice grain was decreased by 76.6% to 97.0%. In comparison to single planting of milk vetch or rapeseed, mixed-planting of milk vetch, rapeseed, and ryegrass showed better effects on reducing the Cd content in rice."

Further research revealed that mixed-planting and turning over green manures effectively increased the iron plaque content in rice root and improved the content of soil DOM, resulting in more effectively controlling the Cd uptake by rice.

"This means that the application of green manure is a suitable measure for safely utilizing Cd-contaminated soil, and mixed-planting green manures is a more effective practice in controlling the Cd uptake in rice. The findings showed that the safe production of rice is practicable in Cd-contaminated paddy fields by using green manures in south China," Cao said.