Aggregate stability and carbon distribution in Oxisol under no-tillage system in Uberaba, Minas Gerais State, Brazil | Estabilidade de agregados e distribuição do carbono em Latossolo sob sistema plantio direto em Uberaba, Minas Gerais

English. The use of no-tillage system (SNT) with cover plants improves soil aggregation. The aim of this study was to evaluate the stability of aggregates in water and carbon distribution in different aggregates class in Oxisol in no-tillage system, Uberaba, MG, Brazil. It was evaluated two areas in SNT: crop of corn + brachiaria and corn + crotalaria. An area adjacent to the savanna was taken as a condition of the original soil. It was collected samples of soil deformability 0-5 and 5-10 cm, soil depths which was evaluated the stability of aggregates stable in water, by means of indices of aggregation: mean weight diameter (MWD) and geometric mean diameter (GMD). It was also evaluated the distribution of the mass of aggregates and carbon per sieve class. It was found that, regardless of depth, the area of savanna showed higher values for DMP, DMG and carbon. Among the cultivated areas, the system of crop corn + brachiaria showed higher values of DMP and carbon of aggregates in detriment of the area corn + crotalaria. These results indicate that the crop in SNT of corn + brachiaria increases soil aggregation and carbon aggregates when compared to the system of corn + crotalaria.

Portuguese. O uso do sistema plantio direto (SPD) com plantas de cobertura melhora a agregação do solo. O objetivo desse trabalho foi avaliar a estabilidade dos agregados em água e a distribuição do carbono nas diferentes classes de agregados de Latossolo Vermelho em sistema plantio direto, em Uberaba, MG. Foram avaliadas duas áreas em SPD: cultivo de milho + braquiária e milho + crotalária. Uma área de cerrado natural adjacente às áreas foi tomada como condição original do solo. Foram coletadas amostras de solo indeformadas nas profundidades de 0-5 e 5-10 cm, sendo avaliada a estabilidade dos agregados estáveis em água, por meio dos índices de agregação: diâmetro médio ponderado (DMP) e diâmetro médio geométrico (DMG). Também foi avaliada a distribuição da massa dos agregados e carbono por classe de peneira. Verificou-se que, independente da profundidade, a área de cerrado apresentou os maiores valores de DMP, DMG e carbono. Entre as áreas cultivadas, o sistema de cultivo de milho + braquiária apresentou maiores valores de DMP e carbono dos agregados em detrimento a área de milho + crotalária. Estes resultados indicam que o cultivo em SPD do milho + braquiária aumenta a agregação do solo e o carbono dos agregados quando comparado ao sistema de milho + crotalária. Aggregate stability and carbon distribution in Oxisol under no-tillage system inUberaba, Minas Gerais State, BrazilAbstractThe use of no-tillage system (SNT) with cover plants improves soil aggregation. The aim of this studywas to evaluate the stability of aggregates in water and carbon distribution in different aggregatesclass in Oxisol in no-tillage system, Uberaba, MG, Brazil. It was evaluated two areas in SNT: crop ofcorn + brachiaria and corn + crotalaria. An area adjacent to the savanna was taken as a conditionof the original soil. It was collected samples of soil deformability 0-5 and 5-10 cm, soil depths whichwas evaluated the stability of aggregates stable in water, by means of indices of aggregation:mean weight diameter (MWD) and geometric mean diameter (GMD). It was also evaluated thedistribution of the mass of aggregates and carbon per sieve class. It was found that, regardless ofdepth, the area of savanna showed higher values for DMP, DMG and carbon. Among the cultivatedareas, the system of crop corn + brachiaria showed higher values of DMP and carbon of aggregatesin detriment of the area corn + crotalaria. These results indicate that the crop in SNT of corn +brachiaria increases soil aggregation and carbon aggregates when compared to the system ofcorn + crotalaria.