Effects of rapeseed straw incorporation on the availability of heavy metals in soil

Abstract

Straw return has been proven to be an effective method for disposing agricultural residues. However, the influence of straw return on heavy metal availability of soils has been rarely reported. In the present study, a series of 60-day incubation experiments was carried out to investigate the effects of rapeseed straw incorporation on the availability of heavy metals (Zn, Cu, and Fe) in soils. The results showed that the incorporation of rapeseed straw into soil significantly increased the availability of Zn, Cu, and Fe. Compared with the control, the highest diethylenetriaminepentaacetic acid (DTPA)-extractable Cu content (2.89 mg/kg) occurred on day 3, and the highest DTPA-extractable Fe content (124.64 mg/kg) occurred on day 6 with 6 g/kg rapeseed straw doses, respectively. The highest DTPA-extractable Zn content (4.19 mg/kg) appeared on day 30 with 20 g/kg rapeseed straw doses. Interestingly, rapeseed straw incorporation had an insignificant impact on soil pH, and the pH therefore played a minor role in controlling the availability of Zn, Cu, and Fe.