Cadmium phytoavailability evaluation in rice-soil system using a field capacity-derived soil solution extraction: An entire growth period study in subtropical China

Abstract

While the evaluation of cadmium (Cd) phytoavailability in rice (Oryza sativa L.)–soil systems has attracted considerable attention in recent years, the results vary based on the evaluation method used. The objective of this work was to use field capacity-derived soil solution extraction (SSE) to evaluate the Cd phytoavailability in two typical paddy soils (purple paddy soil and red paddy soil) during an entire rice growth season. Compared to three conventional extraction methods diethylenetriaminepentaacetic acid (DTPA) extraction, toxicity characteristic leaching procedure (TCLP), and HCl extraction], field capacity-derived SSE resulted in the strongest correlation between extracted Cd and the Cd contents in different rice tissues (root, gem, leaf, ear, husk, and brown rice). When the data for the two soil types were combined, SSE was the best predictor of total accumulated Cd in rice, with linear correlation coefficients of 0.836, 0.831, 0.919, and 0.909 for the tillering stage, heading stage, filling stage, and mature stage, respectively. In contrast, TCLP was only suitable for predicting total Cd accumulation in the heading and mature stages (linear correlation coefficients of 0.813 and 0.931, respectively), while DTPA was only effective in the heading stage (linear correlation coefficient of 0.8306). These results demonstrate the potential of field capacity-based SSE to predict Cd phytoavailability in soil–rice systems with different soil types.