Temporal variability and the effect of fertilization on biochemical properties of grassland soils from Galicia (NW Spain).

The aim of this study was to analyze the effects of soil management, particularly inorganic fertilizer, and to monitor the temporal variability of soil biochemical properties in two grassland plots under contrasting management and located next to each other, trying to link climate and soil biochemical properties. We recorded the following biochemical properties: labile carbon, microbial biomass-C, soil basal respiration, net nitrogen mineralization, and catalase, dehydrogenase, CM-cellulase, b-glucosidase, invertase, casein-protease, BAA-protease, urease, phosphodiesterase, phosphomonoesterase and arylsulphatase activities. Soil microbial activity was higher in the unfertilized plot than in the fertilized plot. Seasonal patterns were identified for some biochemical properties, especially when they were expressed on an organic carbon basis. Additionally, an equation to assess soil quality showed that the unfertilized plot had better quality that the fertilized plot. Our data show that temporal variability should be taken into account when using soil biochemical properties as indicators of soil quality.