Effect of Addition of Farmyard Manure and Lime on Chemical Fractionation of Chromium in Soils and its Bioavailability to Maize

Abstract

Glasshouse experiment was carried out by growing maize crop in a tubewell water irrigated soil after spiking with different levels of chromium (Cr) in the presence and absence of amendments. The experiment was laid out in a completely randomized factorial design with three replications. Maize crop was harvested at 45 days of growth. The soil samples after harvest of maize were collected. To study the change in bioavailability of Cr to maize in the presence of amendments, soil samples collected after harvest were analyzed for transformations in Cr associated with different soil fractions namely, exchangeable + water soluble, carbonate bound, easily reducible oxide bound, organic matter bound, reducible oxides and residual fractions. The results revealed that with the increase in level of applied Cr, the content of Cr in maize shoot increased from 1.85 to 28.2 mg kg−1. The application of farmyard manure (FYM) decreased the Cr content by 2.6 per cent in maize shoot at 320 mg kg−1 of applied Cr in comparison to uncontaminated treatment. Application of lime also decreased the shoot Cr content by 11.5 per cent up to 160 mg kg−1 of applied Cr. It was observed that increase in levels of Cr increased the Cr content in each soil fraction with higher increase in more labile fraction and further transformation of Cr to relatively lesser available fraction. Addition of amendments significantly decreased the concentration of exchangeable + water soluble Cr, carbonate bound, easily reducible oxide bound fractions but increased the organic matter bound, reducible oxide bound and residual fraction of chromium.