Volume 25, Number 1, 2001

The high risk of agricultural activities demands the adoption of risk-assessment methods based on the integration of climatic and pedologic parameters, thus allowing the establishment of state policies concerning crop insurance. Based on the Brazilian Land Evaluation System, a methodology was drawn to elaborate a pedoclimatic zoning of the lands in the State of Goiás and Federal District for the planting of rainfed rice (Oriza sativa L.) (110 days-cycle). Fertility deficiency was assessed in relation to the sum of bases, […]

Two toposequences on the coastal plain of Rio Guaratuba (SP) were studied to define the pedological and deposition/storage evolution by means of macromorphological soil analysis. The first sequence shows the change of a Podzol into organic soil on marine sandy sediments, whereas the second one shows the relationship of a Gley Soil on continental sediments with a Podzol soil on marine sediments. Marine sedimentation was found to form sandbanks with internal depression zones, which allowed the development of a Podzol […]

The effects of native semiarid vegetation deforestation on soil and water losses caused by erosive rainfall in Haplargid were studied. The data covering the period of 1983-1990 were obtained from the Experimental Station of Sumé (Paraíba, from Brazil) of the Universidade Federal da Paraíba (UFPB). The treatments consisted of two deforested runoff plots, two runoff plots with native semiarid vegetation, two deforested watersheds and two watersheds with native semiarid vegetation. The deforested runoff plots, had soil losses of 61.7 and […]

The direct consequences of inadequate soil management are erosion, reduction of productivity and loss of sustainability. The indicators of soil structure quality are important tools for evaluating sustainability of management systems. This study aimed to evaluate the aggregation of typic dystrophic Red Latosol (Oxisol) under different management systems at cerrado region in Sete Lagoas, Minas Gerais, Brazil. Among the studied management systems, no-tillage presented higher percentage of aggregates in the > 2 mm class, smaller percentage in the < 2 mm and < 1 mm classes, […]

This study analyses the correlations among erosivity parameters and soil losses, between June 24, 1979 and October 10, 1994, in an Oxisol from the Unidade de Execução de Pesquisa de Âmbito Estadual at Dourados – EMBRAPA, Southern Mato Grosso, Brazil. Rainfall erosivity, runoff, and rainfall-runoff parameters were analysed through simple and multiple linear regression and nonlinear regression, to: (a) define an erosivity parameter for individual storms, aiming to improve the use of the USLE at that site; (b) obtain the […]

A set of 874 erosive individual rainfall occurrences was selected from a continuous serie of twenty-three years of recording rain gauge data. All the selected rainfall occurrences were analized. The rainfall erosivity factor computed was 7074 MJ mm ha-1 h-1 y-1, which is expected to occur at least once every 2.33 years, with a probability of occurrence of 42.92%. The values of the annual erosivity indexes at that site expected for the return periods of 2, 5, 10, 20, 50, and 100 years, were respectively 6,696, 8,730, 10,076, […]

A field experiment was carried out from 1990 to 1994 in the experimental area of the Soil Department at the Federal University of Santa Maria, State of Rio Grande do Sul, Brazil, on an Hapludalf to evaluate the potential of some winter legumes as N suppliers to no-tillage corn. A completely randomized block design with split-plots was used, with the winter crops in the main plots and the N rates for corn in the split-plots. In the main plots, the […]

The direct consequences of inadequate soil management are erosion, productivity reduction and loss of sustainability. This study aimed to evaluate the resistance to penetration and permeability of soil to water under management systems used in the cerrado region. The study was conducted at Embrapa Corn and Sorghum, in Sete Lagoas (MG), using a cerrado phase, very clayey, typic dystrophic Red Latosol (Acrusthox). The native cerrado provided lower soil density, higher macroporosity, higher total volume of pores, and consequently, smaller resistance […]

Atrazine, an herbicide of the s-triazine group, was used in laboratory experiments to determine its mineralization and sorption on samples of a Dusky-Red Latosol under conventional and no-tillage systems. Atrazine ring-labeled 14C was added to the soil samples, with the 14CO2 being produced and atrazine-14C soil extracts analyzed by liquid scintillation. The results showed very low mineralization rates of atrazine, which were correlated with the total carbon and nitrogen contents, as well as with soil humic fractions. Atrazine mineralization decreased […]

Soil is an important component of the ecosystem. Its management affects air and water quality. Nowadays, the soil potential to sequester carbon and, therefore, mitigate global warming, is an emergent subject. The main goals of this research were: (a) to evaluate the potential of cover crops (black oat, blue lupine (priori to oat + vetch), velvet bean and jack bean) used in corn production systems to increase soil organic carbon (OC) and total nitrogen (TN) content in a sandy-loam typic Paleudalf, in […]