ABSTRACT Sequential crops may be affected by herbicide residuals in the soil. In corn crop there are reports of problems when the crop is sown soon after application of ACCase-inhibiting herbicides. The aim of this study was to evaluate safety intervals for the application of ACCase-inhibiting herbicides before sowing corn in different soils. Two experiments were conducted in a greenhouse, and in the field conditions. In both, the experimental design were completely randomized in factorial scheme 6x4+1 (6 periods of application x 4 herbicides + 1 control) with five replications. The treatments were: haloxyfop-P-methyl (124.7 g ha-1), clethodim – formulation 1 (192 g ha-1), quizalofop-P-ethyl (100 g ha-1) and clethodim formulation 2 (192 g ha-1) in applications at 15, 10, 5, 3, 1 and 0 days before sowing in sandy and clayey soil. In the greenhouse, formulations based on clethodim were more safety in both types of soils, and safety intervals for clethodim-based herbicides were 5 days and greater than 15 days for quizalofop-P-ethyl and haloxyfop. Haloxyfop should not be applied on day of sowing in clay soil. In the field none of the treatments compromised the development and yield of the crop, even when applied on the day of sowing.

RESUMO. A exploração dos recursos naturais, pelas atividades agrícolas ao longo do tempo resultou na necessidade de buscar medidas alternativas para recuperação do solo degradado. O cultivo de plantas de cobertura é uma alternativa que gera grandes benefícios aos sistemas agrícolas, viabilizando a exploração dos recursos naturais, água, luz e nutrientes e recuperação de solos degradados. O objetivo deste trabalho foi avaliar o percentual de taxa de cobertura, massa fresca e massa seca das culturas de cobertura de outono e inverno e a composição florística de plantas daninhas. O trabalho foi conduzido em condições de campo em solo classificado como Latossolo Vermelho eutroférrico, na região do município de Palotina, Estado do Paraná, Brasil. O delineamento experimental utilizado foi o de blocos ao acaso, com quatro repetições, os tratamentos foram constituidos por sete culturas de coberturas: nabo forrageiro, linhaça, triticale, centeio, canola, crambe, aveia; e área de pousio. As espécies que apresentaram os maiores valores de taxa de cobertura, massa fresca e massa seca foi o nabo forrageiro, canola e crambe. No levantamento florístico e fitossociológico, as espécies com maior incidência foram Amaranthus retroflexus, Commelina benghalensis L., Brachiaria plantaginea e Gnaphalium spicatum.

ABSTRACT. The long-term exploitation of natural resources by agricultural activities has resulted in the need for alternative measures to restore degraded soil. The cultivation of cover crops can generate great benefits for agricultural systems, enabling the exploitation of natural resources, including water, light and nutrients, as well as the recovery of degraded soils. This work aimed to assess the coverage rate, fresh mass and dry mass of cover crops from fall and winter as well as the floristic composition of the weeds. The work was conducted in field conditions in soil classified as eutroferric Red Oxisol in the region of the city of Palotina, Paraná State, Brazil, using a random block experimental design with four replications. The treatments consisted of seven cover cultures: wild radish, linseed, triticale, rye, rapeseed, crambe, oats and fallow. The species with the highest coverage rates and fresh mass and dry mass values were wild radish, rapeseed and crambe. In the floristic and phytosociological data, the species with the highest incidence were Amaranthus retroflexus, Commelina benghalensis L., Brachiaria plantaginea and Gnaphalium spicatum.