Soil cover plants on water erosion control in the South of Minas Gerais

Water erosion is responsible for soil, water, carbon and nutrient losses, turning into the most important type of degradation of Brazilian soils. This study aimed to evaluate the influence of three cover plants under two tillage systems on water erosion control in an Argisol at south of Minas Gerais state, Brazil. The cover plants utilized in the study were pigeon pea, jack bean and millet, under contour seeding and downslope tillage. Experimental plots of 4 x 12 m, with 9% slope, under natural rainfall were used for the quantification of losses of soil, water, nutrients, and organic matter. One experimental plot was kept without plant cover (reference). Higher erosivity was observed in December and January, although a great quantity of erosive rainfall was detected during the whole raining period. Contour seeding provided a greater reduction of water erosion than downslope tillage, as expected. The jack bean under contour seeding revealed the lowest values of soil, water, nutrients and organic matter losses

Relationship between physical attributes, clay fraction mineralogy and aluminum forms in soil

O alumínio (Al) é um dos elementos mais abundantes em massa nos solos brasileiros, estando presente em diferentes minerais e formas. Considerando a carência de informações sobre a sua participação no comportamento físico do solo, buscou-se, no presente estudo, avaliar a relação entre a mineralogia da fração argila, formas de Al e atributos físicos de diferentes solos. Para tanto, foram coletadas amostras deformadas e indeformadas dos horizontes A e B de solos representativos das Zonas Fisiográficas Sul e Campos das Vertentes do estado de Minas Gerais. As amostras foram submetidas às caracterizações física, química e mineralógica. Estudos de correlação mostraram que os atributos físicos dos solos estudados estavam associados às diferentes formas de Al presentes e à mineralogia da fração argila: as formas de Al amorfas e menos cristalinas associaram-se mais aos atributos físicos relacionados com a agregação das partículas do solo, podendo esta associação ser atribuída à afinidade deste elemento com a matéria orgânica, enquanto os componentes cristalinos associaram-se mais aos atributos físicos relacionados com a organização estrutural dos solos._________________________________________________________________________________ ABSTRACT: Aluminum (Al) is one of the most abundant elements in weight in Brazilian soils, found in different minerals and forms. Considering the lack of information about its participation in the physical behavior of soil, the present study aimed to evaluate the relationship between the mineralogy of the clay fraction, different forms of Al and physical attributes of different soils. Disturbed and undisturbed samples of A and B horizons of representative soils from the South and Campos das Vertentes physiographic regions in the State of Minas Gerais were therefore collected. The samples were subjected to physical, chemical and mineralogical characterizations. Correlation studies performed with the resulting data from the different characterizations showed that the physical attributes of the different studied soils are associated to the different forms of Al and to the mineralogy of the clay fraction: the amorphous and less crystalline forms of Al were more associated to physical attributes related with particle aggregation, such association being ascribed to the affinity of this element with organic matter, while the crystalline components were more associated to physical attributes related with the structural organization of the soils