Researches evaluating the use of mulch has contributing to optimize soil management towards sustainability, and improving soil quality. The objective of this study was to evaluate the efficiency of mulching on the reduction of erosion in a soil with sorghum (Sorghum bicolor L. Moench) crops subjected to simulated rainfall and increased soil organic carbon. The experiment was carried out from August to December 2013 under field conditions, using a randomized block design with three replications. The treatments consisted of sorghum with mulch, using the local vegetation available in the area; and sorghum without mulch. Simulated rainfalls were performed in three different periods of the crop cycle (initial, intermediate, and final), using a rainfall simulator. The use of mulch in soils with sorghum crops was efficient in improving soil water retention in all phases of the crop, and maintaining soil moisture during the rainfall intervals used, resulting in the absence of plant water loss, and greater contribution to soil organic carbon.

The objective of this study was to evaluate the soil organic carbon fractions and the carbon management index (CMI) in a cohesive oxisol under different uses. Conventional cassava planting (CC), pasture (PP), and 7-and 12-year agroforestry systems (AF7 and AF12, respectively), were tested against secondary forest (SF). Soil samples of these areas were physically fractionated in order to determine total organic matter (TOC) as well as the labile-(LOC) and non-labile (NOC) fractions of the soil organic matter, as well as carbon management index (CMI). Total organic C ranged from 14.17 to 27.20 g kg -1 of soil, showing no differences in the surface layer among the land uses as compared to the secondary forest. No differences were found in the surface layer for LOC as well, except for the AF12 where LOC was higher. This condition accounts for higher microbial activity and nutrient cycling in the soil. This system also showed higher CMI values, pointing to a better response of soil quality under long-term agroforestry system. This system improved soil organic matter, regardless of the depth. On the other hand, conventional cassava and planted pasture systems reduced carbon in soil. In conclusion, the agroforestry system is the best choice of farmers, when they seek for better soil quality.

Objetivo: Verificar o efeito da luz e do corte do tegumento no processo germinativo de M. pubescens A. St.-Hl. Métodos: Para este estudo, analisou-se quatro tratamentos: T1: luz constante, com tegumento cortado; T2: luz constante, com tegumento intacto; T3: ausência de luz, com tegumento cortado; T4: ausência de luz com tegumento intacto. O experimento foi conduzido em delineamento inteiramente casualidade com 8 repetições contendo 10 sementes cada. As avaliações ocorreram a cada dois dias até o 10° dia, em que foi observado que não havia mais germinação das sementes. Por meio da contagem de sementes germinadas foram obtidas as seguintes variáveis: Percentagem de Germinação; Índice de Velocidade de Germinação e Tempo Médio de Germinação. Resultados: Não houve diferença significativas quanto a influência da luz no processo germinativo de M. pubescens, para quebra de dormência, observou-se que as sementes de tegumento intacto apresentaram o Índice de Velocidade de Germinação e Coeficiente de Velocidade de Germinação maiores quando comparadas àquelas que tiveram tegumento cortado. Conclusão: A luminosidade não influencia a germinação de M. pubescens e a quebra de dormência, por meio do corte do tegumento, promove a perda do vigor nessas sementes.

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