Long term effect of fertilizer application on cadmium uptake on oat (Avena sativa) plant

Abstract

Phosphate fertilizers contain varying amounts of Cd and other heavy metals as contaminants from phosphate rock (PR). Periodic applications of these fertilizers resulted in measurable accumulations of Cd in soils and in harvested crops. A long term field study for fourteen cropping seasons (1992-2006) was conducted on an experimental plot located at the Norwegian University of Life Sciences (Ås, Norway) to evaluate the effect of application of cadmium enriched phosphate fertilizer on soil solution dynamics of cadmium and Cd accumulation in Oat (Avena sativa). Treatments consisted of three NPK fertilizer sources containing 1, 90, 381 mg Cd kg-1 P and supplying 0.03, 2.7, 11.43 g Cd ha-1yr-1. Surface soil samples (0-20 cm) were collected after harvesting of plant in 1992, 1995, and 2006. Plant samples were analyzed for 1992, 1995, 1997, 2002 and 2006. Soil samples were analyzed for total and extractable Cd, pH, dissolve organic carbon (DOC) and PO4 3-. Analysis of plant samples was done for total concentration of Cd and plant uptake of Cd was calculated. A general trend of decrease in plant Cd with increased soil pH was observed throughout the experiment period except 1992 where plant Cd concentration did not significantly change with soil pH. Increasing the addition of Cd input through fertilizers only increased the Cd concentration in soil, but the Cd concentration in oat grain was not affected significantly. NH4NO3 - extractable Cd in the soil increased with increasing rate of Cd through different sources but the concentration of extractable Cd in the soil decreased with increased pH throughout the experimental period except in 1995 where soil pH did not show any consistent effect on extractable Cd. Plant Cd did not show any significant correlation with extractable Cd in soil. Hence the concentration of Cd in oat grain was not significantly affected by Cd input through fertilizers.