The objective of this study was to assess the relative efficiency of single superphosphate (SS), partially acidulated rock phosphate (PARP) and fused magnesium thermal phosphate (MTP) as sources of P and other nutrients for eucalypt plantations in two soils of the cerrado region: an alic quartz-sand (50 g kg-1 of clay) and an alic dark-red latosol (230 g kg-1 of clay). Experiments were carried out under greenhouse conditions at the University of São Paulo, Piracicaba, State of São Paulo, Brazil, […]

A field experiment was carried out on a dark-red latosol (Oxisol) of the Centro de Pesquisas Novartis-Seeds, in Uberlândia, State of Minas Gerais, Brazil. The objective of this study was to evaluate the effects of irrigation, side-dressed application of urea, and urea partially substituted by ammonium sulphate on losses of NH3-N by volatilization in corn crop. The fertilizers were applied at 25 and 36 days after planting. The treatments, arranged in randomized complete block design, were: (i) control, (ii) urea, […]

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 […]