Addition of clay to sand: Effect of clay concentration, water content and bulk density on soil respiration

摘要

Two laboratory experiments were conducted to determine the effect of clay concentration, bulk density and water content on soil respiration. In Experiment 1, clay isolated from Vertosol subsoil was added at 50, 100, 200, 300 and 400 g kg(-1); 20 g kg(-1) mature wheat residue were also added. Cumulative respiration per g soil was significantly higher with >= 200 g clay kg(-1), per g soil organic C (SOC from residue + clay) it was not influenced by these clay concentrations, whereas it was reduced by 50 and 100 g clay kg(-1) In Experiment 2, clay was added at 50 and 300 g kg(-1) to sand, adjusted to three water contents (0.146, 0.163, 0.179 g g(-1)) and three bulk densities (1.3, 1.45, 1.6 Mg m(-3)). Cumulative respiration per g SOC was higher with 300 g clay kg(-1). Clay addition to sand decreased soil respiration per g C, whereas hulk density and water content have little effect.