Enzymatic activity as an indicator of soil quality in pastures under inoculation and nitrogen fertilization

Abstract

The degradation of native grasslands in Southern Brazil demands sustainable practices that support soil quality recovery. This study evaluated the activity of the enzymes β-glucosidase and acid phosphatase as indicators of soil biological quality in native grassland under microbial inoculation and reduced nitrogen fertilization. Β-glucosidase is related to carbon cycling, and acid phosphatase to organic phosphorus mineralization, both being sensitive indicators of microbial activity. The experiment was conducted in a native grassland area in curitibanos, santa catarina, using a randomized block design with five treatments and five replications. Treatments included a control (50% nitrogen fertilization) and four treatments with the same nitrogen dose combined with inoculation using Azospirillum brasilense, Bacillus subtilis, Pseudomonas fluorescens, or Rhizobium tropici. Soil samples were collected at the end of the pasture cycle (april 2024), at a depth of 0–10 cm. Samples were analyzed at embrapa soja using the colorimetric method described. The average enzymatic activities were 180.04 micrograms of p-nitrophenol per gram per hour for β-glucosidase and 1,209.77 micrograms of p-nitrophenol per gram per hour for acid phosphatase. The pr > fc values (0.22 and 0.98, respectively) indicated no statistically significant differences among treatments. Although the effects of microbial inoculation were not statistically significant, the high enzymatic activity levels suggest an active soil microbiota, with no harm to biological quality, indicating potential for use in sustainable systems.