The Mechanism of Silkworm Excrement Organic Fertilizer to Reduce the Cd Availability in Paddy Soil

Abstract

Cadmium (Cd) contamination of agricultural soils is a global concern, as it can cause the accumulation of Cd in food. In this study, an incubation experiment was carried out to investigate the effect on Cd availability in paddy soil amended four kinds of silkworm excrements organic fertilizer (SEs). And the soil amended with chicken manure organic fertilizer (CM) and no organic fertilizer (CK) were as control. The SEs and CM were added to soil at the rate of 3% (w/w). The results showed that the available Cd content in soils decreased by 27.3–40.9% and 14.1–27.3% in treatments of SEs compared to the CK and CM after incubation 60 days. The potential mechanisms for reducing the availability of Cd were subjected, including: (i) high aromaticity of SEs; (ii) SEs improved pH and OM content of soil; (iii) XRD pattern proved that Cd in soil was mainly stabilized in the form of CdCO3 and Cd(OH)NO3 by adding SEs. In conclusion, SEs application was an effective method to decrease Cd availability in paddy soil.