CARBONO ORGÂNICO E MICRORGANISMOS NO DESENVOLVIMENTO DA SOJA NOS ESTADOS DO MARANHÃO, PARÁ E TOCANTINS

Abstract

The use of beneficial soil microorganisms has emerged as a promising strategy to enhance plant development and reduce reliance on synthetic inputs, particularly in no-tillage agricultural systems. However, the effectiveness of these bioinputs may be limited in environments with low availability of labile carbon, which is essential for microbial growth and activity. This study evaluated the effects of a commercial inoculant based on Bacillus amyloliquefaciens, Bacillus subtilis, and Priestia megaterium, applied alone or in combination with a commercial product formulated with organic carbon, on root development, nodulation, and soybean yield in three tropical regions with dry winters: Tocantins, Pará, and Maranhão. The experiments were carried out in commercial fields, using a randomized block design with ten replicates. The variables assessed included plant stand, root length, number of nodules per plant, nodule weight, and yield. The results showed that the combination of the inoculant with organic carbon led to significant improvements in key variables, with increases of up to 41% in the number of nodules, 64.5% in nodule weight, 32.1% in root length, and 7.9% in yield, depending on the location. The most expressive response was observed in Maranhão, although beneficial effects were consistently recorded across all regions. It is concluded that the combined use of bioinputs and assimilable carbon sources enhances soil biological activity and improves soybean agronomic performance, representing a technically recommended practice for sustainable production systems.