P Pools in Barley Detritusphere Are Influenced by N and P Addition to the Soil

Abstract

The aim of this experiment was to determine the effect of soil amendment with inorganic N and P on nutrient availability in the detritusphere of low N and P crop residue. To a loamy sand (50% water holding capacity) without fertiliser, with inorganic N or P or both were added and then filled into two PVC caps incubated without (S N, S+P or S+NP) or with barley straw (10 g kg−1; B+N, B+P or B+NP). The open ends of the two PVC caps were covered by fine mesh. For barley treatments, barley straw was placed between the meshes. The open ends of the two PVC caps were pressed together and held tightly with rubber bands. Unamended control had no straw between the caps. After 14 and 28 days of moist incubation, soil at 0–1 mm distance from the surface (detritusphere) was collected. Compared to inorganic treatments alone and the unamended control, P pools and available P and available N in the barley detritusphere were lower whereas microbial biomass P and N were higher. In soil with inorganic P, the decrease of citrate P, HCl-P and resin P in barley detritusphere relative to soil only was greater than without P, but the increase in MBP was not affected by P addition. Microbes in this soil had a limited capacity to accumulate P, likely due to the spatial separation of soil and residues. P released from citrate P, HCl-P and resin P in detritusphere may have been transferred into the residues.