Volume 23, Number 3, 1999

Tensiometers were installed in a 25 m2 area plot, every 15 cm, at depths varying from 30 to 240 cm, with three repetitions, to determine the matric potential (φm) of a “Terra Roxa Estruturada Latossólica” soil. Its volumetric water content was also indirectly measured by using the soil water retention curve. The θ-method (Libardi et al., 1980) fitted the soil redistribution profiles (θ vs t) with determination coefficients (R2) greater than 0.98. The hyphotesis of a unit hydraulic gradient was […]

The association of conservation tillage with cover crops is an important tool for improving soil quality. When legumes are used as cover crops there is an increase in nitrogen (N) availability for the first crop in succession (immediate effect). However, the long term use of legumes as cover crop increases soil N availability (residual effect). This long-term experiment was carried out to evaluate the immediate effect and residual effect of cover crops on a Paleadulf from Rio Grande do Sul, […]

Organic matter is considered the soil attribute most sensitive to the changes triggered by the management systems. The objective of this study was to evaluate the effect of nine years using three soil tillage systems -conventional tillage, reduced tillage and no tillage- on soil chemical characteristics of a Humic Cambisol in southern Brazil. Soil samples were collected in September 1996 at depths of 0-2, 2-5, 5-10, 10-15, and 15-20 cm, and analysed for C and N contents in total organic […]

This work aimed to measure and analyze total rainfall (P), rainfall intensity and five-day antecedent rainfall effects on runoff (R); to compare measured and simulated R values using the Soil Conservation Service Curve Number method (CN) for each rainfall event; and to establish average R/P ratios for observed R values. A one-year (07/01/96 to 06/30/97) rainfall-runoff data study was carried out in the Capetinga watershed (962.4 ha), located at the Federal District of Brazil, 47° 52′ longitude West and 15° […]

Soil pans caused by tillage operation may restrict root growth thus reducing yield. Physical properties of soil such as bulk density and soil strength have been used as parameters for management decision in order to promote root growth. This work was carried out to evaluate the relationship among these soil parameters and root growth, in a 7 year field experiment with five soil tillage systems and soybean (Glycine Max L.). The tillage systems combined summer and autumn tillage with disk […]

Crop residue in direct contact with the soil surface is very effective in dissipating the energy of raindrop impact on soil, being also a physical barrier against interrill overland flow. The presence of these residues may strongly affect the interrill soil erosion process. A study was carried out with the objective of evaluating the relationship between interrill erosion and amounts of crop residue in direct contact with soil surface and to verify the differences in this relationship for corn and […]

The characterization and quantification of soil organic matter as water soluble carbon, labile carbon and light organic matter may be used to characterize the rehabilitation of degraded areas. Soil samples were thus collected on a hillside cut submitted to reclamation, presenting different types of vegetal covering during November 1994, in the district of Viçosa. The treatments consisted of areas of soils without vegetation, recovering areas with mainly legumes, recovering areas with mainly grass, soils under grass and soils under natural […]

A greenhouse experiment was carried out to evaluate the effect of urban waste compost on soil fertility and on total and extracted contents (DTPA 0.005 mol L-1 pH 7.3) of the elements Fe, Mn, Zn and Ni in a sandy Red-Yellow Podzolic soil (Ultisol). The yield of dry matter of Sorghum bicolor plants and the content of P, K, Ca, Mg, Fe, Mn, Zn and Ni were evaluated in plant tops as a function of compost rates of 0, 12.5, […]

This experiment was conducted in leaching tubes filled with soils classified as Typic Quartzipsament (AQ), Typic Hapludox (LV) and Rhodic Typic (LE). Sewage sludge was periodically added and incorporated to the soils in a total amount corresponding to 156,0 t ha-1 (dry weight basis), for an incubation period of 310 days. The soils were then treated with water and the following salt solutions: 0.9 mol L-1 KCl; 0.9 mol L-1 KNO3; 0.3 mol L-1 K2SO4 and 0.3 mol L-1 Ca(NO3)2. […]

This paper describes a technique that retrieves soil moisture from monopolarized SAR data. The technique uses SAR data obtained by the Japanese Earth Resources Satellite (JERS-1) and two empirical models. One relates the backscatter coefficient with the complex permitivity (Dubois’s model), and the other relates the complex permitivity with soil parameters such as soil moisture (Hallikainen’s model). First, the SAR data were calibrated to obtain the backscatter coefficient and the Dubois’s model was inverted to achieve the complex permitivity. The […]