Influence of Soil Moisture Regimes, Amendments and Ageing on Cadmium Availability in a Sandy Loam Soil

Abstract

In a range of cadmium (Cd) spiked soil the effects of soil moisture regimes, amendments and ageing on Cd availability were assessed. A sandy loam soil was spiked with Cd @ 0, 10 and 25 mg kg-1 soil through its nitrate solution. Lime (5%), farmyard manure (20 t FYM ha-1) and zinc (25 mg Zn kg-1) were added as amendments. The treated soil samples were incubated at 35 °C for 1, 45 and 90 days at field capacity and submerged soil moisture regimes. Available Cd was extracted with 0.005 M DTPA extractant and determined by ICP-AES. The results revealed that there was a temporal decrease in the available Cd with ageing and was in the order of 90 days > 45 days > 1 day. The magnitude of decrease in Cd availability was higher with the addition of amendments in the order of lime > FYM > Zn > unamended soil. The decrease in available Cd was further pronounced under submerged moisture regime than under field capacity. An overall reduction in the per cent recovery of DTPA-Cd was observed under submergence compared to field capacity moisture regime in lime, FYM, Zn amended soils and unamended soil. Least percent recovery was obtained under submergence combined with lime amendment at 90 days of incubation. The results enable us to understand the effect of ageing coupled with different amendments under various moisture regimes on Cd availability.