Soil enzyme activities and microbial community modulation after addition of poultry litter amendment enriched with Bacillus spp.

ABSTRACT The global consumption of mineral fertilizers has increased in the last 60 years. However, these fertilizers can negatively affect the soil and the atmosphere. The application of soil amendments focusing on sustainable farming practices can reduce the effects of mineral fertilization. In this study, we investigated the effects of increasing the dose of a commercial amendment using poultry litter enriched with Bacillus (SMARTGRAN) in different types of soils in Brazil under microcosm conditions. These different types of soils were classified as Nitossolo, Argissolo arênico, Argissolo alumínico, Latossolo distroférrico, and Latossolo distrófico. The biological activity in the soil was quantified by measuring the enzymes arylsulfatase, beta-glucosidase, and acid phosphatase. Additionally, bacterial diversity was evaluated by amplicon sequencing of the 16S rRNA gene and conducting phylogenetic analyses of three types of soils, which were selected because of their occurrence and fertility profiles. The results showed an increase in those enzyme activities under all conditions. The results of the analysis of the bacterial community in Nitossolo, Argissolo arênico, and Latossolo distrófico soil types showed a direct relationship between the bacterial composition in the soil and the increase in the amendment dosage. The alpha diversity indices decreased considerably because some plant-growth-promoting bacteria, such as Bacillus, Massilia, Paenibacillus, and Rhizobium, increased in relative abundance. The results indicated that an organic amendment enriched with Bacillus had a beneficial effect on different types of soil in Brazil.