Atividade microbiana e produtividade da soja em sistemas integrados de cultivo e manejo hídrico no solo

Abstract

Soybean production in sandy soils in areas with a history of water regime abnormalities, resulting from climatic factors, has been a major challenge for agronomic research. The objective of the present work was to evaluate biological and soil fertility attributes as well as soybean yield in integrated cropping systems of plants in sandy soils with and without water replacement. The experiment was carried out in soil classified as dystrophic Red Yellow Argisol with sandy texture. The average annual rainfall in the region is 1,500 mm. The experiment was carried out during two soybean harvests from May 2018 to March 2020. The experimental design was in a completely randomized split-range, with four replications. Each strip, with an area of 6 m x 30 m, was established by the soybean cropping system in the summer and cover plant species, constituting the following treatments: T1: Soybean, corn; T2: Soybean and Urochloa brizantha; T3: Soybean, corn intercropped with Urochloa brizantha; T4: Soybean, Urochloa brizantha with green manures - pigeon pea and sunn hemp. Each strip was subdivided into a 30 m² subplot and water was replaced. Soil chemical fertility in the 0-10 cm and 10-20 cm depths, and microbial activity in the 0-10 cm layer were evaluated. Nodulation, foliar nutrient contents and soybean yield were also analyzed. The production system with the cultivation of Urochloa and legumes intercropped, in the autumn and winter months, promoted an increase in nodulation, soybean productivity and microbial activity in the soil. The use of water replacement positively influenced soil microbiological attributes, specifically microbial biomass, metabolic and microbial coefficient and dehydrogenase activity. There were positive correlations between soil microbiological attributes, nodulation and soybean yield. Soil chemical fertility attributes and foliar nutrient contents in soybean were not influenced by treatments and water management.