Weight loss in relation to environmental factors during the decomposition of maize and wheat roots in a seasonally-dry tropical region

Abstract

Wheat and maize root materials showed differences in the magnitude of weight loss from bags with coarse (1 mm) or fine-mesh (3 μm pores) buried in soil. For maize, weight loss differed in these two types of bag at two soil depths (5 and 12.5 cm). The total weight loss from root bags were: maize roots (during 214 days), at 5cm depth, 79 and 50% in coarse- and fine-mesh bags, respectively, and for wheat roots (during 275 days), at 5cm depth, 72 and 45% in coarse- and fine-mesh bags, respectively. The CO 2 evolution rates from decomposing roots showed a significant positive relationship with weight loss. In all batches of the maize and wheat roots the relative decomposition rates (RDR) rapidly increased initially and subsequently declined. During the first 4 months the maize root RDR at 12.5 cm depth exceeded that at 5cm depth. Coarse-mesh RDR was always higher than that of fine-mesh bags. The two major environmental variables, temperature and soil moisture were positively related to the rate of wheat root decomposition, but negatively correlated with the decomposition rates of maize roots.