Intra-annual variation in biochemical properties and the biochemical equilibrium of different grassland soils under contrasting management and climate

In this study, the effects of different management practices on soil biochemical properties were evaluated in three pairs of grassland soils (unmanaged and managed) located in three areas of Galicia (NW Spain) where different types of climate prevail. Variations in soil biochemical properties were monitored throughout 1 year. Changes in soil temperature, soil moisture content, and particularly soil location and soil management affected the values of the biochemical properties. Comparatively higher levels of enzyme activity were observed in the unmanaged grasslands than in the managed grasslands, especially for β-glucosidase activity and the enzymes involved in the P and S cycles (phosphodiesterase, phosphomonoesterase, and arylsulphatase activities). A biochemical equilibrium index was used to evaluate soil quality. Although variations in the index were observed throughout the year, the values mainly depended on soil management and revealed that unmanaged grasslands were in a situation of biochemical equilibrium throughout the study period, while no such equilibrium was observed in managed grasslands for most of the studied period.