SUMMARYVegetable production in conservation tillage has increased in Brazil, with positive effects on the soil quality. Since management systems alter the quantity and quality of organic matter, this study evaluated the influence of different management systems and cover crops on the organic matter dynamics of a dystrophic Red Latosol under vegetables. The treatments consisted of the combination of three soil tillage systems: no-tillage (NT), reduced tillage (RT) and conventional tillage (CT) and of two cover crops: maize monoculture and maizemucuna intercrop. Vegetables were grown in the winter and the cover crops in the summer for straw production. The experiment was arranged in a randomized block design with four replications. Soil samples were collected between the crop rows in three layers (0.0-0.05, 0.05-0.10, and 0.10-0.30 m) twice: in October, before planting cover crops for straw, and in July, during vegetable cultivation. The total organic carbon (TOC), microbial biomass carbon (MBC), oxidizable fractions, and the carbon fractions fulvic acid (C FA ), humic acid (C HA ) and humin (C HUM ) were determined. The main changes in these properties occurred in the upper layers (0.0-0.05 and 0.05-0.10 m) where, in general, TOC levels were highest in NT with maize straw. The MBC levels were lowest in CT systems, indicating sensitivity to soil disturbance. Under mucuna, the levels of C HA were lower in RT than NT systems, while the C FA levels were lower in RT than CT. For vegetable production, the C HUM values were lowest in the 0.05-0.10 m layer under CT. With regard to the oxidizable fractions, the tillage systems differed only in the most labile C fractions, with higher levels in NT than CT in the 0.0-0.05 m layer in both summer and winter, with A produção de hortaliças em sistemas conservacionistas tem crescido no Brasil com reflexos positivos na qualidade do solo. Considerando que os sistemas de manejo alteram a quantidade e a qualidade da matéria orgânica, este trabalho teve por objetivo avaliar a influência de diferentes sistemas de manejo e cobertura vegetal na dinâmica da matéria orgânica de um Latosssolo Vermelho distrófico, cultivado com hortaliças. Os tratamentos avaliados consistiram na combinação de três sistemas de manejo de solo: plantio direto (PD); plantio com preparo reduzido (PPR); e preparo convencional (PC), e duas coberturas vegetais: milho e consórcio milho e mucuna. No inverno, foram cultivadas hortaliças; e no verão, cobertura vegetal para palhada. O delineamento experimental utilizado foi de blocos ao acaso com quatro repetições. As amostras de solo foram coletadas na entrelinha de cultivo da hortaliça em três profundidades (0,0-0,05; 0,05-0,10 e 0,10-0,30 m), em duas épocas de amostragem: em outubro, antes do plantio das culturas para formação de palhada; e em julho, durante o cultivo da hortaliça. Foram determinados o carbono orgânico total (COT), o carbono da biomassa microbiana (CBM), das frações oxidáveis, e o carbono das frações ácido fúlvico (C AF ), ácido húmico (C AH ) e hum...