Transformations of native and added chromium among soil fractions by addition of amendments and different contact periods

Abstract

An experiment was carried out to study the effect of farm yard manure (FYM) and lime addition on the distribution of native and added chromium among various soil chromium (Cr-VI) fractions, namely exchangeable and water soluble (Ex + WS), carbonate bound (CARB), easily reducible oxides (ERO's), organic matter bound (OM), reducible oxides (RO's), and residual (RES) fractions of non-contaminated surface soil. The study was performed with three different treatments (FYM@1%, lime @1% and no amendment) and for eight contact periods (1, 3, 7, 21, 42, 63, 84, and 105 days). The overall trend in Cr fractions shows that a more significant proportion of native Cr was associated with the residual fraction, followed by reducible oxide and organic matter fractions. The lowest concentration of Cr was observed to be in the exchangeable fraction. The addition of different concentrations of Cr increased the Cr content in each fraction with a higher increase in more labile fractions (water-soluble + exchangeable) at a lesser contact period, and further transformation of Cr to relatively lesser available fractions was observed with the increase in the time of contact.