Mudanças na comunidade bacteriana do solo em função de sistema de cultivo da soja e formas de inoculação de Bacillus subtilis

Abstract

Integrated systems with soybean cultivation in the summer and pastures in the offseason, as well as the use of biological inputs, have been studied to maximize production and reduce environmental impact. The present study aimed to evaluate different forms of application of Bacillus subtilis in soybean crops in cropping systems already consolidated in the field and its effect on the soil bacterial community. The experiment was designed in a double factorial, during the 2023/24 harvest in an area with an integrated crop-livestock system established since 2017 using the cultivation systems: Soybean - fallow and Soybean - Urochloa ruziziensis. Within these systems, treatments were carried out with application of B. subtilis via sowing furrow, transport of the bacteria by organic compost and also with application in total soil, in order to evaluate microbial activity and changes in the microbiome both in the total soil and rhizosphere, as well as soil fertility attributes and soybean growth. The application of Bacillus subtilis caused changes in the frequency of bacterial genera of agricultural importance in the composition of the soybean rhizosphere microbiome when applied via seed furrow and compost. In total soil, the application was not sufficient to cause changes in the microbiome, but it caused changes in microbial activity attributes and also in greater phosphorus absorption by soybean. The application of the compost also stood out, increasing phosphorus and foliar nitrogen in the integrated system. The functionality of bacterial genes related to the nitrogen cycle was increased by the application of B. subtilis in the seed furrow and via organic compost.