CONICET | Buscador de Institutos y Recursos Humanos

Studies of degraded semiarid regions have shown that organic-residue addition is a sound restoration alternative. We examined the effects of a single dose (40 Mg ha-1) of biosolids compost (BC) and compost of the organic fraction of municipal solid waste (MC) 6 yr after they were applied to a sandy soil of NW Patagonia. Results were compared with an inorganic fertilization (IF, 100 kg N + 35 kg P ha-1) and an unamended control. We measured plant cover, biomass, and diversity, and chemical, biological, and biochemical soil properties. We did not found any significant effect of treatments on plant attributes. However, effects on soil properties were significant and more persistent with composts than with IF, especially with BC, which had higher organic C and nutrients than MC. Total soil C and N were twice as high in the BC-amended treatment as in the control and IF. Soil extractable P was 4-fold and 2-fold higher in BC and MC treatments, respectively, than in the control, and even higher than in the IF treatment in response to BC. The highest β-glucosidase and acid phosphomonoesterase activities were found in the BC treated soil, related to higher C and P in the soil and to higher activities of both enzymes in the biosolids compost. The highest phenol oxidase activity was found in MC and in the MC treated soil. Potential respiration and K2SO4-extractable C were higher in the compost treatments, but there was no difference in microbial biomass C between the compost treatments and the control. Despite the fact that the soil was coarse textured and a single moderate dose of compost was applied, recovery of soil chemical, biological, and biochemical properties was long-lasting, indicating that application of urban compost is a feasible restoration practice in this semiarid region.