Actividad microbiana y enzimática en suelos forestales y agrícolas

Resumen

We characterized the microbial and enzymatic activity in upper mineral horizons under forest plantations and agricultural fields in the Ventania region, Province of Buenos Aires, Argentina. The pH in the soil of forest plantations was, on average, 1.2 units lower than in the adjacent agricultural fields. In the forest plantations, there were also significant increases in total organic carbon, and coarse particulate organic carbon (POCc), total N content, and the C:N ratio. The microbial respiration rate was higher in the forest plantations (17.8 ± 1.5 mg CO2 100 g-1 day-1) in comparison to the agricultural fields (10.2 ± 1.4 mg CO2 100 g-1 day-1). A close relationship between respiration and the POCc increase was observed. The enzymatic activity of sulphatase and chitinase was also greater in forest plantations, indicating greater mobilization of N and S. In both systems, the phosphatase enzyme activity was high as expected given the high phosphorus sorption rate (58 %) of the soils in Ventania. Forest and agriculture land use affected soil carbon and nitrogen dynamics in different ways. Microbial respiration is positively associated with coarse particulate organic carbon level. The results suggest that N and S mobilization was greater in forest plantations.