Effect of Straw Removal and Irrigation Systems on the Community of Growth-Promoting Organisms

Resumo

Introduction: The use of plant growth-promoting microorganisms in agricultural crops, such as sugarcane, has become a common practice to sustainably improve productivity. Organisms such as Bacillus subtilis, Trichoderma spp., and Azospirillum brasilense play crucial roles in promoting plant health, enhancing nutrient absorption, and suppressing pathogens. However, the interaction between these microorganisms and management practices, such as straw removal and different irrigation systems, is not well understood. Objective: This study aimed to investigate how straw removal and different irrigation systems affect the community of plant growth-promoting organisms in sugarcane cultivation areas. Methodology: The study was conducted in sugarcane fields in the Goianésia region, Goiás, Brazil. Areas irrigated by sprinkler, pivot, and rainfed systems were evaluated, with one and two years of straw removal, as well as areas without straw removal. The presence and abundance of Bacillus subtilis, Trichoderma spp., and Azospirillum brasilense were quantified using microbiological culture techniques and molecular analysis. Soil samples were analyzed for chemical and physical composition to correlate the microbiological data with soil conditions. Main Results: Areas with two years of straw removal showed the highest levels of Bacillus subtilis and Trichoderma spp., indicating that continuous straw removal favors the proliferation of these organisms. Pivot irrigation was associated with higher concentrations of Azospirillum brasilense, suggesting that this irrigation system creates more favorable conditions for its development. Furthermore, the presence of these beneficial organisms correlated with reduced pathogen levels and improved nutrient uptake by plants. Conclusion: Prolonged straw removal positively influences the presence of growth-promoting organisms such as Bacillus subtilis and Trichoderma spp., which play a crucial role in maintaining soil health and agricultural productivity. The irrigation system also affects the microbial community, with pivot irrigation favoring the development of Azospirillum brasilense. These results highlight the importance of an integrated management approach that considers soil microbiology for optimizing productivity and agricultural sustainability.