Aspectos produtivos da sucessão soja milho, resistência à penetração do solo e atividade enzimática sob diferentes estratégias de formação de palhada

Abstract

The objective of this study was to evaluate the agronomic performance of corn and soybean in different crop rotation systems. The research was conducted at the Experimental Farm of the Faculty of Agricultural Sciences of UFGD, in Dourados, MS, during the 2021/2022 and 2022/2023 growing seasons. The experiment was arranged in a randomized block design with 16 treatments and four replications. The treatments consisted of monocropping of corn, Urochloa brizantha cvs. BRS Marandú, BRS Paiaguás, BRS Piatã, BRS Xaraés, and Urochloa ruziziensis cv. Kenedy, as well as corn intercropped with each forage species, with or without suppression using nicosulfuron associated with atrazine. In both soybean seasons, plant height, first pod insertion height, number of branches per plant, number of pods per plant, thousand-grain weight, and yield were evaluated. For the corn crop, plant height, stem diameter, ear length, number of grains per ear, thousand-grain weight, and yield were analyzed. The amount of straw after forage management was also assessed, and in 2023, soil penetration resistance and the activity of the enzymes arylsulfatase and β-glucosidase were measured. The treatments did not influence soil penetration resistance or the activity of arylsulfatase and β glucosidase, whose values were considered high across all treatments. Additionally, no statistical differences were observed in soybean yield components or productivity in either production year. For corn, only yield in the second 2022 season was affected by the treatments, with the lowest yields observed in the unsuppressed intercropping treatments of corn with U. ruziziensis and corn with U. brizantha cv. Paiaguás, which negatively impacted corn production. Regarding straw production for no-tillage, no statistical differences were detected among treatments in either growing season. However, in the second 2021 season, low rainfall resulted in straw production below 6 Mg ha⁻¹ year⁻¹ in the monocropping treatments of corn, BRS Marandú, BRS Paiaguás, and BRS Xaraés, as well as in the intercropping treatments corn+Paiaguás with suppression, corn+Ruziziensis with and without suppression, and corn+Xaraés with suppression. The inclusion of tropical forages, either in sole cropping or intercropped with corn in the second season, is a viable strategy, as it does not compromise the productivity of the main crops.