Microbial Activity of Bacillus spp. in Soil as a Function of Liming and Gypsum Application in Pasture

This study hypothesized that the combination of limestone and gypsum could promote higher pasture yield and affect soil biological properties, such as microbial biomass and enzymatic activity, and alter the population of Bacillus within a pasture system with U. brizantha. A factorial design was employed with two treatments—without and with lime (0 and 1.6 ton ha−1)—and four gypsum doses (0, 0.5, 1.0, and 2.0 ton ha−1) in experimental field plots. Six successive cuts were made in the pasture, and at the end, soil samples were analyzed for microbial biomass, enzymatic activity, and the putative Bacillus spp. community. The association of gypsum application with liming modified soil microbial activity attributes. It was found that only the application of gypsum reduced the microbial biomass and increased the concentration of putative Bacillus spp. in the soil, which correlated positively with increased crop yield, especially with the higher gypsum dose applied. The combined use of limestone and gypsum did not alter the microbial biomass and showed the best performance in increasing yield with the lowest dose of gypsum applied. In both cases evaluated, with and without the use of gypsum in conjunction with liming, it may be possible to achieve significant increases in biomass accumulation in pasture.