秸秆移除对降低土壤镉含量的效果有限

秸秆移除是重金属中低污染农田安全生产广泛采用的措施之一,其目的是通过移除积累在秸秆中的重金属,逐步降低土壤重金属含量。本文通过对文献报道的数据进行模拟计算,以评估水稻秸秆移除对降低土壤镉(Cd)含量的效果。基于田间试验数据,水稻秸秆Cd含量与土壤Cd含量呈显著的线性关系。根据回归方程和秸秆平均生物量估算,在土壤总Cd含量为0.5～5.0mg·kg~(-1)范围内,单季水稻秸秆可移除的Cd占耕层土壤Cd总量的0.23%～0.37%(平均值为0.27%),秸秆和籽粒Cd总移除率的平均值大约为0.30%。研究表明,水稻秸秆移除对降低耕层土壤Cd含量效果非常有限。

Straw removal has a limited effect on decreasing cadmium concentration in soil

Straw removal is a widely used practice in low-moderately contaminated agricultural soils with the aim to remove heavy metals from the soils. However, there are few reports on the effectiveness of this practice. Here, we used field-based data reported in the literature to evaluate the potential of rice straw removal for reducing cadmium(Cd) concentration in soil. Straw Cd concentration correlated linearly and significantly with soil Cd concentration. The regression equation obtained and average straw biomass were used to estimate the amounts of Cd removal in straw from soils with 0.5~5 mg Cd·kg^-1. Straw Cd removal represents 0.23%~0.37%(mean 0.27%) of the total Cd in the plow layer. Including Cd removal in rice grain increases the removal rate to approximately 0.30%. The results suggest that rice straw removal has a limited effect on decreasing cadmium concentration in soil.