Soil erosion evaluation in a small watershed in Brazil through 137 Cs fallout redistribution analysis and conventional models

An investigation of rates and patterns of soil erosion on agricultural land cultivated with sugarcane was undert a ken using the 137Cs technique, USLE (Universal Soil Loss Equation) and WEPP (Water Erosion Prediction Project) model. The study was carried out on a representative catchment of a small watershed of the Piracicaba river basin, State of São Paulo, Brazil, called Ceveiro watershed, well known for its severe soil degradation caused by erosion. The results from the 137Cs technique indicate that most part of the studied area (94%) are eroded at erosion rates that go up to 59 Mg ha-1 y-1, with a weighted average rate of 23 Mg ha-1 y-1 . The weighted average rate of infield deposition and sediment retrieval that occurs in only 6% of the total area was estimated to be around 12 Mg ha-1 y-1 . These values led to very high net soil loss from the field, with rates of the order of 21 Mg ha-1 y-1 , which represents a sediment delive ry ratio of 97%. A linear correlation between soil erosion rate estimated by the 137Cs technique and the amount of available K in the top soil layer (0-20 cm) was observed. Based on this correlation the estimated amounts of net and gross K loss in the grid area due to soil erosion were of 0.2 and 1.52 kg ha-1 y-1, respectively. The erosion rate estimated by USLE was 39 Mg ha-1 y-1 and by WEPP model 16.5 Mg ha-1 y-1 with a sediment delivery of 12.4 Mg ha-1 y-1 (75%). The results are a confirmation that the soil conservation practices adopted in the area are very poor and can explain the high siltation level of water reservoirs in the watershed

Solid capillary support for fluid fertilizer: I. Residual effect experiment

Procurou-se avaliar o comportamento agronômico do Suporte Solido Capilar para Fertilizantes Fluídos (SC), que é um produto fertilizante experimental desenvolvido pela ULTRAFÉRTIL com comportamento potencial de Fertilizante de Solubilização Lenta. Procurou-se avaliar seu efeito sobre as plantas e sobre os solos além de compará-lo com fertilizantes convencionais, através de um ensaio de efeito residual. O SC não se comportou como Fertilizante de Solubilizaçao Lenta, igualando-se aos outros tratamentos. O K quando aplicado via SC é melhor aproveitado pelas plantas e a presença do SC no solo provoca variações nos teores de P, Ca e S - SO4-2 no solo.A residual effect experiment was conducted to evaluate the agronomic behaviour of the Solid Capilar Support for Fluid Fertilizer (SC). SC is an experimental fertilizer developed by ULTRAFERTIL and has possibilities as a slow Release fertilizer. Plants absorb K better when it is applied via SC, and the presence of SC in the soil changes, P, Ca and S-SO4-2 contents

Avaliação agronômica do suporte sólido capilar para fertilizantes fluídos: II. Aplicação de micronutrientes

The application of micronutrients in the soil, in a homogeneous way, with the least contact with soil particles may increase its agronomic efficiency. Storing a solution of fertilizers in a solid porous medium, which is used as a vehicle for application, links great homogeneity to low soil contact. The Solid Capillary Support for Fluid Fertilizers (SC) was used as porous solid medium. It is a compacted cylinder made of gypsum (CaSO4 2H2O), developed experimentally by ULTRAFERTIL. The SC was an efficient way in supplying micronutrients, resulting in similar or better yields in relation to direct application in the soil.A aplicação de micronutrientes no solo de maneira homogênea e com o mínimo de contato com as partículas sólidas do solo, pode aumentar sua eficiência agronômica. Armazenar uma solução de fertilizantes num meio sólido poroso, que é utilizado como veículo na aplicação, alia grande uniformidade e pouco contato com o solo. Como meio poroso utilizou-se o Suporte Sólido Capilar para Fertilizantes Fluídos (SC), que consiste de um cilindro de gesso (CaSO4 2H(2)0) compactado, desenvolvido em caráter experimental pela ULTRAFÉRTIL. O SC mostrou-se eficiente no fornecimento de micronutrientes via solo, proporcionando produções iguais ou superiores, em relação à aplicação direta no solo

Soil erosion evaluation in a small watershed in Brazil through 137 Cs fallout redistribution analysis and conventional models

An investigation of rates and patterns of soil erosion on agricultural land cultivated with sugarcane was undert a ken using the 137Cs technique, USLE (Universal Soil Loss Equation) and WEPP (Water Erosion Prediction Project) model. The study was carried out on a representative catchment of a small watershed of the Piracicaba river basin, State of São Paulo, Brazil, called Ceveiro watershed, well known for its severe soil degradation caused by erosion. The results from the 137Cs technique indicate that most part of the studied area (94%) are eroded at erosion rates that go up to 59 Mg ha-1 y-1, with a weighted average rate of 23 Mg ha-1 y-1 . The weighted average rate of infield deposition and sediment retrieval that occurs in only 6% of the total area was estimated to be around 12 Mg ha-1 y-1 . These values led to very high net soil loss from the field, with rates of the order of 21 Mg ha-1 y-1 , which represents a sediment delive ry ratio of 97%. A linear correlation between soil erosion rate estimated by the 137Cs technique and the amount of available K in the top soil layer (0-20 cm) was observed. Based on this correlation the estimated amounts of net and gross K loss in the grid area due to soil erosion were of 0.2 and 1.52 kg ha-1 y-1, respectively. The erosion rate estimated by USLE was 39 Mg ha-1 y-1 and by WEPP model 16.5 Mg ha-1 y-1 with a sediment delivery of 12.4 Mg ha-1 y-1 (75%). The results are a confirmation that the soil conservation practices adopted in the area are very poor and can explain the high siltation level of water reservoirs in the watershed

Multiperspective analysis of erosion tolerance

Erosion tolerance is the most multidisciplinary field of soil erosion research. Scientists have shown lack in ability to adequately analyze the huge list of variables that influence soil loss tolerance definitions. For these the perspectives of erosion made by farmers, environmentalists, society and politicians have to be considered simultaneously. Partial and biased definitions of erosion tolerance may explain not only the polemic nature of the currently suggested values but also, in part, the nonadoption of the desired levels of erosion control. To move towards a solution, considerable changes would have to occur on how this topic is investigated, especially among scientists, who would have to change methods and strategies and extend the perspective of research out of the boundaries of the physical processes and the frontiers of the academy. A more effective integration and communication with the society and farmers, to learn about their perspective of erosion and a multidisciplinary approach, integrating soil, social, economic and environmental sciences are essential for improved erosion tolerance definitions. In the opinion of the authors, soil erosion research is not moving in this direction and a better understanding of erosion tolerance is not to be expected in the near future

Asymmetries of cattle and crop productivity and e ciency during Brazil\u27s agricultural expansion from 1975 to 2006

Brazil has global importance for food production and conservation of natural resources. The country has plans to increase yields and commitments to decrease deforestation that require higher productivity. Plans and policies for the growth of Brazilian agriculture, however, have been made without an integrated analysis of the harvest and not supported by a universal metric regarding its e ciency. Applying methods to model ows of energy and matter along food supply chains for agricultural production from 1975 to 2006, we found that crop and cattle harvests and their productivity have increased during the last four decades in consolidated and deforestation frontier regions. Yet in 2006, crop protein production was 20 times larger than cattle protein, using an area 2.6 times smaller than pastures. Crop protein productivity was 0.25 ton.ha–1 with emissions of 2 ton GHG per ton of protein, while cattle productivity was 0.01 ton. ha–1 with emissions of 283 ton GHG per ton of protein. From 1975 to 2006, the portion of crop protein and energy going to feed increased while the portion going to direct human consumption decreased. Our ndings suggest that more e cient food systems would be achieved by a combination of intensi cation of cattle systems, optimization of feed-meat systems and an increase in the share of the consumption of crops as a source of protein. We suggest an initial road map to the expansion of the cultivated area and intensi cation of agriculture for zero deforestation, e cient and sustainable land use and food systems where cattle pasture intensi cation is a transition that will last until the expansion of crops replace all pasture present on suitable arable land. During this transition, pasture area will decrease until it is lim- ited only to marginal non-arable lands. Such change could be achieved by a robust strategy that combines penalties and incentives and prevents the risks of a rebound e ect for the intensi cation of agriculture

Environmental Costs of Government-Sponsored Agrarian Settlements in Brazilian Amazonia

Brazil has presided over the most comprehensive agrarian reform frontier colonization program on Earth, in which ~1.2 million settlers have been translocated by successive governments since the 1970's, mostly into forested hinterlands of Brazilian Amazonia. These settlements encompass 5.3% of this ~5 million km2 region, but have contributed with 13.5% of all land conversion into agropastoral land uses. The Brazilian Federal Agrarian Agency (INCRA) has repeatedly claimed that deforestation in these areas largely predates the sanctioned arrival of new settlers. Here, we quantify rates of natural vegetation conversion across 1911 agrarian settlements allocated to 568 Amazonian counties and compare fire incidence and deforestation rates before and after the official occupation of settlements by migrant farmers. The timing and spatial distribution of deforestation and fires in our analysis provides irrefutable chronological and spatially explicit evidence of agropastoral conversion both inside and immediately outside agrarian settlements over the last decade. Deforestation rates are strongly related to local human population density and road access to regional markets. Agrarian settlements consistently accelerated rates of deforestation and fires, compared to neighboring areas outside settlements, but within the same counties. Relocated smallholders allocated to forest areas undoubtedly operate as pivotal agents of deforestation, and most of the forest clearance occurs in the aftermath of government-induced migration

Influência do avaliador no resultado da classificação de terras em capacidade de uso.

Por sofrerem uma exploração agrícola descontrolada, recursos naturais como o solo e a água tendem ao seu esgotamento. Como conseqüência, problemas ambientais que afetam diretamente a qualidade de vida da população acabaram sendo uma constante. Para minimizar esta situação o planejamento de uso das terras tornou-se prerrogativa básica para o uso adequado de áreas agrícolas