Wood ash effects on C and N dynamics of a soil from a pinus pinaster plantation

Abstract

Effects of wood ash (loose and pelleted) on chemical properties and microbial activity in an Arenosol from a Pinus pinaster plantation were assessed through laboratory incubation. Wood ash was applied at a rate of 0, 4 and 8 g kg^-1 soil both alone or together with N. Loose ash significantly increased pH values and extractable nutrients from the soil. Net nitrification was stimulated by it application. Amounts of microbial biomass C were lower in soils with loose ash than in the control. Basal respiration was not affected by treatments. Effects increased with the increment of applied ash and when applied together with N. Application of pelleted ash produced smaller changes in soil chemical characteristics, net nitrification and C dynamic. Results suggest that, in N limited soils, wood ash should be applied in the pelleted form because changes in chemical soil properties are slower and the potential loss of N is much less as compared to the loose ash. Pelleted ash should be applied together with N fertilizer to improve soil N availability.