Biomassa microbiana e resistência do solo à penetração em função do consórcio de milho e Brachiaria spp. na produtividade da soja

Abstract

The benefits of introducing Brachiarias to the systems are due to the increased contribution of straw and roots to the soil that promotes improvements in the soil's physical, chemical, and biological qualities. In this context, the objective of this work was to determine the best alternatives for the production of soybeans, forage, and straw for soil coverage in the no tillage system by evaluating the microbial biomass of the soil and its mechanical resistance to penetration (RP), the productivity of Brachiarias and maize straw, and the subsequent soybean yield. The study was conducted based on an experiment installed in February 2014, located at the Experimental Farm of the Faculty of Agricultural Sciences of the Federal University of Grande Dourados (UFGD), in Dourados-MS, during soybean harvests in 2018/2019, 2019/2020, and 2020/2021; and second maize harvests in 2018, 2019, and 2020. The experiment consisted of 16 treatments and four repetitions, arranged in a randomized blocks design. The treatments dealt with soybean production in succession to maize, soybean in succession to Brachiarias brizantha: cvs. (Xaraés, Piatã, Marandú and Paiaguás), and Brachiaria ruziziensis, submitted to three cropping systems, as follows: a) single forage crops; b) forage intercropped with maize and with herbicide suppression, and c) forage intercropped with maize and without herbicide suppression. Straw yield and soybean yield assessments were performed on all 16 treatments. To examine the microbial biomass and RP, 11 treatments were chosen, which corresponded to soybean cultivation in succession to single maize, single forage, and maize intercropped with forage with herbicide suppression. In the treatments of B. brizantha cv. Marandú and cv. Piatã single, a higher accumulation of microbial biomass carbon (C-BMS) was verified. The highest soybean yield occurred when produced in the straw of B. brizantha cv. Marandú and cv. Piatã single. In the areas cultivated with B. brizantha cv. Piatã and cv. Paiaguás and B. ruziziensis single presented lower averages of RP in the layers of 0-10 cm and 30-40 cm. The lowest straw yield, the lowest soybean yield, the lowest accumulation of C-BMS, and the highest RP were shown in the single maize/soybean succession.