Influência de diferentes densidades de semeadura de adubos verdes na comunidade de plantas daninhas em sistema de plantio direto orgânico de milho

Abstract

Weed management stands out as one of the main challenges in organic agriculture due to the lack of alternatives to replace synthetic herbicides and manual labor for their removal. Green manure plants have been studied to assist in managing weed populations in agroecosystems. The objective of this study was to determine the influence of different sowing densities (0, 40, 80, 100, 120, and 160% of the recommended dose) of a green manure polyculture with black oats + hairy vetch forage radish grown in an organic no till system during winter on the phytosociological indices of spring-summer weeds. The field experiment was conducted in a randomized block design with four replications at the experimental area of the Federal University of Fronteira Sul (UFFS). Green manure plants were sown during the winter of 2022, followed by corn planting the following spring. Evaluated variables included the diversity and abundance of weeds, above ground biomass production of weeds, readily germinable seeds in the soil, and correlation estimation of these variables with corn yield. Data were subjected to normality analysis, analysis of variance, and, when applicable, regression analysis to fit models representing observed phenomena or multiple mean comparison test (p<0.05). Total dry biomass of weeds was affected by the treatments, with emphasis on treatments 80, 100, 120, and 160%. Different densities of the green manure polyculture affected the dry biomass of brachiaria, especially treatments 100, 120, and 160%. The treatments affected the phytosociological indices of the sampled plants in the area. but did not show a significant difference in the number of non-dormant weed seeds (m²). The treatment with 100% of the recommended dose showed higher productivity (kg ha-1), followed by treatments 120 and 40%, respectively.