Effects of straw and simulated root exudates on aggregate dynamics and aggregate-associated carbon in consideration of FACE condition

Abstract

In order to investigate the role of residue and root carbon inputs in soil carbon changes due to elevated CO2, soil sample weighted 500 g collected from field under elevated CO2 and ambient CO2 condition, respectively, were incubation for one year with addition of straw and chemical matters, and then examined the different aggregates fraction and aggregated-associated carbon in soil. The results showed that the soil carbon for macro- (>250 μm) and micro-aggregates (250-53 μm) increased by 8.8-73.1% due to the addition of straw and by 11.2-111.7% (p<0.05) due to the exudates. Conversely, soil carbon in the clay and silt-sized particles (<53 μm) was decreased by 12.3-22.1% (p<0.05) by glucose and decreased even further with the addition of straw, whereas it was increased only by 5.8-11.8% with phenol and organic acid. These results could help to understand deeply the effects of elevated CO2 on the dynamics of both soil aggregates and carbon in a field due to variations in the crop straws and root exudates forms. © Springer-Verlag Berlin Heidelberg 2013.