Nitrogen mineralization potential (No) for ten Rio Grande do Sul, Brazil, soils was studied with corn grown on 20 kg pots for 45 days, as compared with nitrogen mineralized in aerobic incubation for 32 weeks. No values ranged from 108.6 to 210.8 mg kg-1, being similar to the total nitrogen mineralized. Mineralization velocity was higher during the first four weeks, and overall mineralization rate varied from 0.2985 to 0.3181 week-1 among soils. The correlation coefficient between corn absorbed nitrogen and […]

Although periodically flooded ecosystems represent 25% of the total Amazon area, they contribute to 75% of timber production. Both periodically flooded and upland ecosystems are greatly diverse in species belonging to Leguminosae family. Some of these species are currently exploited, but the economic potential of the vast majority has been overlooked. The knowledge of the plant growth characteristics of these species under nursery conditions is the first step to understand their biology and establish artificial woodlands in deforested areas. This […]

Estimates of deforestation in the Brazilian Amazon, primarily for shifting cultivation and pastures, exceed the land area for the State of Rondônia. An experiment was conducted on a Xanthic Hapludox near Manaus, Brazil to establish soil nutrient depletion patterns and fertilizer and lime requirements for continuous cultivation after slash-and-burn clearing. Yield responses to N, P, K, Mg, S, B, Cu, Mn, Zn and lime were evaluated during eight years of cultivation. Seventeen crops were grown during the period from 1981 […]

The spatial variability of soil characteristics in the Planalto Médio region, State of Rio Grande do Sul, Brazil, was studied in six areas cultivated with soybean. Semivariance and variance analyses were applied to the data obtained by systematic soil sampling to confirm and detail results obtained by nested analysis of variance, and to estimate the variance of characteristics within soil mapping units and the range of its application for land evaluation. Field work was performed from December, 1989 to March, […]

A cartographic simulation in a Geographical Information System (GIS) was used to evaluate the environmental impacts of different forest management strategies on a watershed scale. The project was conducted in a small (2 km2) watershed located at northern coast of the State of Espírito Santo, Brazil, which is inserted in an area of eucalypt-clone plantation comprised by the agro-industrial complex Aracruz Celulose S.A. Potential impacts were assessed by applying the Universal Soil Loss Equation (USLE) in a GIS, where different […]

The application of a surface complexation model to determine the effect of the pH and the phosphate concentration in the soil solution on the adsorption of phosphorus in two acric soils, was evaluated. Surface and subsurface samples were collected from two Oxisols of Ribeirão Preto and Guaíra, northern of the State of São Paulo, Brazil, in 1993. The samples were incubated with increasing amounts of calcium carbonate and hydrochloric acid to change the pH. The adsorption curves were obtained by […]

A rotating-boom rainfall simulator, operating at a constant rainfall intensity of 64 mm h-1 for sufficient time to runoff reaches steady-rate, was used to investigate water erosion and other related parameters in three tillage systems. The experiments were carried out immediately following corn and wheat harvesting, in a sandy loam Red-Yellow Podzolic soil (Paleudult) with a 0.066 m m-1 average slope, in Eldorado do Sul, State of Rio Grande do Sul, Brazil, from 1992 to 1994. No-tillage, chiselling and disk-plowing […]

The aim of this study was to identify corn production systems using green manure crops showing characteristics of sustainability. The experiments were carried out on a Yellow-Red Podzolic soil, 5.5% slope, at Federal University of Santa Maria, State of Rio Grande do Sul, Brazil, from 1991 to 1993. Plot dimensions were 3.5 m by 22.0 m, as defined by the methodology of natural rainfall erosion plots. The treatments consisted of: (i) bare soil, (ii) black oat (Avena strigosa) + common […]

The soil erodibility (K-factor) determination by indirect methods has not been adequate for application in Brazilian soils. This paper aimed the development of K-factor evaluation methods depending on easily-assessed chemical, physical and morphological soil properties. Samples from A and B horizons of 22 Brazilian soils bearing argillic horizon were submitted to several chemical and physical analyses and the morphological description of the soil profile was considered. A stepwise multiple linear regression analysis was run, relating the results of those analyses […]

Litholic soils are characterized by moderate to high erodibility and low depth. Due to these attributes, litholic soils require effective conservation practices protecting their thin top soil layer from the high erosion rates in the semiarid regions of the State of Ceará, Brazil. While the consequences of erosion on these soils are well known, the long term effects of this conservation practice on the rate of soil losses and improvement of their properties have been scarcely studied. Mass of retained […]