O processo erosivo é a principal causa de degradação dos solos, trazendo, como consequência, prejuízos ao setor agrícola e ao meio ambiente, com reflexos econômicos e também sociais. Este trabalho foi realizado com o objetivo de avaliar as perdas de solo e nutrientes em diferentes sistemas de preparo num Latossolo Vermelho-Amarelo ácrico típico. Foram instaladas cinco parcelas experimentais contendo os seguintes tratamentos: preparo convencional e cultivo morro abaixo (CMA); preparo convencional e plantio em nível (CEN); preparo com uma grade aradora e uma niveladora e plantio em nível (CNiv); preparo com duas gradagens niveladoras, plantio em nível (NA) e cultivo mínimo em nível (CMN). As perdas de solo foram determinadas pelo método direto durante o ciclo da cultura de algodão, de dezembro de 2005 a junho de 2006. A cada coleta foram retiradas amostras de solo para quantificar as perdas dos nutrientes N, P, K e carbono orgânico (C-org) nos sedimentos. A diminuição no revolvimento do solo proporcionou menores perdas de sedimento, nutrientes e C-org, destacando o CMN como o mais eficiente. As perdas de N, P, K e C-org nos sedimentos apresentaram tendências semelhantes às das perdas de solo, e N, P e K variaram conforme as adubações utilizadas. O C-org foi encontrado em maior quantidade no sedimento. A taxa de infiltração básica (TIB) expressou diferença entre os tratamentos na seguinte ordem em valores crescentes: CMA < CEN<img src="/img/revistas/rbcs/v33n3/a21apro.gif" align="absmiddle"> CNiv<img src="/img/revistas/rbcs/v33n3/a21apro.gif" align="absmiddle"> NA < CMN, demonstrando que os sistemas de preparo que minimizam a movimentação do solo e incrementam C-org aumentam a TIB e diminuem o processo erosivo.

The aim of this study was to evaluate the loss of water and nutrients by laminar runoff in different soil tillage systems subjected to natural rainfall. Five experimental plots were established for the cultivation of cotton in the city of Campo Verde-MT, with the following treatments: CTDP = conventional soil tillage and planting of the cotton in the direction of the slope; CTCP = conventional tillage and contour planting; CP = tillage of soil with a disk harrow and a leveling harrow, followed by contour planting; CoP = tillage by two passes of a leveling harrow followed by contour planting; MTCP = minimum tillage with contour planting. The losses of water by laminar runoff in were determined by the stored volume and samples were taken to quantify nutrient losses in water (nitrite, nitrate, phosphate and potassium). The losses of water by runoff were highest for the CTDP; intermediate for the treatments CTCP, CoP and MTCP, and lowest for the CP. Potassium (K) was the nutrient that had the highest concentrations and losses in water: the highest values were found in the CTDP and CTCP tillage systems, whereas the lowest were observed for the CP, CoP, and MTCP treatments. The concentrations and the losses by water erosion of phosphate (PO4 3-), nitrite (NO2-), and nitrate (NO3-) were low in all of the soil tillage systems compared to the losses of K in this study.

Family farming is important for the production of food for human consumption, but it lacks resources to invest in the soil fertility of its crops. The objective of this study was to analyze whether the use of green manures increases soil fertility in terms of the nutrients N, P and K with low environmental risk for family agricultural production. An experiment was set up in the State of Mato Grosso (Brazil), in randomized complete block design, with a 6 x 3 factorial scheme, four replications, corresponding to 6 types of plants and 3 doses of phosphorus. Leguminous green manure plants were: velvet bean, Crotalaria juncea, Crotalaria ochroleuca and dwarf pigeon pea, in addition to plots with pearl millet and weedy fallow control. Rock phosphate (i.e., reactive natural phosphate) was applied as a source of phosphorus at 0, 50 and 100 kg P2O5 ha-1. The species used as green manure were cut in full bloom and the levels of N, P, K and C in plants and soil were determined. Leguminous green manure plants, after mineralization, increased the stocks of N, P and K in the soil. Crotalaria juncea was the one that reached the highest N accumulation in its constitution, being recommended in the intercropping with species with C/N ratio > 30 to minimize risks of contamination with nitrate in the soil. This work concluded that the managements with green manure plants, especially Crotalaria ochroleuca, are recommended and environmentally safe technical alternatives for family farming.

The aim of this study was to analyze whether the use of green manures in association with rock phosphate rates can guarantee corn yields to family farmers. An experiment was conducted with six types of green manures: Mucuna cinereum, Crotalaria juncea, Crotalaria ochroleuca, Cajanus cajan, Pennisetum glaucum and a weedy fallow control treatment; and three rates of phosphorus (0, 50 and 100 kg P 2 O 5 ha -1 ) in a complete randomized block design. The management with Crotalaria juncea achieved the highest dry mass yield (39.3 Mg ha -1 ) and in year 2 (2016), with the water deficit during the corn cultivation, led to an increase of the root/shoot mass ratio, as well as presented the lowest water deficit sensitivity index (Ky), indicating that it can be an alternative for managing climate change. The highest corn yield (7510 kg ha -1 ) was obtained in the management with the Crotalaria ochroleuca, which defines it as a technically and economically viable alternative for family farming, with corn yield exceeding the average yield of the State of Mato Grosso and production cost lower than the average production cost of corn in the State of Mato Grosso.