Early Response of Soil Microbial Biomass and Activity to Biofertilizer Application in Degraded Brunic Arenosol and Abruptic Luvisol of Contrasting Textures

We tested agriculturally and chemically degraded Brunic Arenosol and Abruptic Luvisol of contrasting textures to establish the early response of soil quality to two different mineral fertilizers (Polifoska and urea) amended with microbes applied in optimal and reduced doses. The soil samples were collected from two fields under maize: one week (I(st)sampling time) and six months (II(nd)sampling time) after fertilization. The laboratory experiment included determination of: catalase activity, dehydrogenase activity, microbial biomass, and basal respiration; pH and dissolved organic carbon (DOC) were also measured. The silty Luvisol was characterized by higher biological activity than the sandy Arenosol. Biofertilizer addition to degraded soils increased the biological activity, even in reduced doses of additives used; however the responses of the tested microbiological indicators were different. Soil texture affected the positive biomass response to biofertilizers which was observed in samples from I(st)sampling time in silty soil, while from II(nd)sampling time in sandy soil. Based on our results, we propose that Polifoska with microorganisms (used in full dose) may be optimal for silty soil. Polifoska (in reduced dose) and urea (both in full and reduced dose) may be recommended for sandy soils. Increasing pH was a stronger driver of soil biological activity than DOC. Long-term field testing is suggested for validating our results.