The effects of continuous sugarcane cropping on the properties of a clayey Yellow Latosol were studied in the region of the Low Coastal Tablelands of Alagoas State, Brazil. Four sites were selected at Caeté mill, São Miguel dos Campos, AL, involving a native forest (Tn) and sugarcane fields cultivated for periods of two (T2), eighteen (T18) and twenty-five (T25) years. The soils were morphologically characterized and undisturbed samples of the A, AB, and BA horizons of each profile were collected […]

The best measures of crop residue quality for soil protection against erosion are the percentage of soil cover and its persistence on the soil surface. These two variables, in turn, may be strongly affected by soil tillage. This study was carried out in Rio Grande do Sul State, Southern Brazil (30°06’S; 51°39’W). Crop residue mulch persistence was evaluated over a fallow period, following the harvest of a soybean crop. Three conservation tillage methods (chiseling, disking, and no-till) were used as […]

Aggregate size and the state of soil aggregation may be influenced by different soil management and cultural practices which lead to changes in soil organic matter content and biological activity. The objective of this study was to verify the relationship between organic carbon and the size and stability of soil aggregates in two planting systems (conventional and direct), three crop rotations (corn/wheat/corn, soybean/wheat/corn and soybean/wheat/soybean), under two soil sample preparation processes: use of 4 and 8 mm sieves before the […]

The implications of soil water availability on the growth of Hamlin variety orange trees were studied in a tableland topsequence in Bahia State. The topsequence consisted of a Podzolic Yellow Latosol, a Yellow Podzolic, and a Gray Podzolic. Soil samples were analyzed for texture and selected soil chemical characteristics. Rainfall data were also collected during the period of the study. Soil water content was measured weekly using a neutron probe to estimate water storage and water availability. Average values of […]

Salt-affected soils are characteristics of arid and semi-arid zones of the world. This study was undertaken at Açu valley region of Rio Grande do Norte State, Brazil, by means of a field experiment conducted from April/90 to January/91. The objective of this study was to evaluate the effects of subsoiling and amendment additions (gypsum, farmyard manure and Copernica cerifera straw), on chemical properties of saline sodic soil. Subsoiling treatment provided beneficial effects decreasing soil exchangeable sodium percentage (ESP) and pH […]

A gibbsitic Red-Yellow Oxisol with electropositive carater was used to study the effect of organic matter on electrochemical properties and dispersion mechanisms. Two organic sources were used, one characterized by non-humified compounds (cattle manure) and another by humified compounds (peat humic acids). The soil was incubated with 0; 7,5; 15,0; 22,5 and 30,0 g kg-1 of organic manure. Water dispersible clay, electrical conductivity, water and KCl pH, and the zero point of saline effect (ZPSE) and superficial electric potential (Ψo) […]

Four strains of Rhizobium leguminosarum bv. trifolii were screened for their use in inoculants for red clover (Trifolium pratense) in the Soil Microbiology Sector, Department of Soils, University of Rio Grande do Sul, Porto Alegre, Brazil, from January 1994 to March 1995. In greenhouse experiments, all four strains presented similar efficiency in nitrogen fixation. However, when mixed strains were used, the strain SEMIA 222 was more effective in nodule formation. In a yeast manitol sucrose medium, growth rate was higher […]

This study was carried out at the Center for Nuclear Energy in Agriculture (CENA), Piracicaba, State of São Paulo, Brazil, with the objective of obtaining information about the effect of different application levels of water/vinasse (100, 200, 400, 600, 800 and 1,000 m3 ha-1) on hydraulic conductivity of soil samples homogeneously packed in columns. A constant head infiltrometer and the instantaneous water profile method were utilized to determine saturated and unsaturated soil hydraulic conductivity, respectively. The increase of the vinasse […]

Soils from the Vale do Rio Doce region in Ipatinga, Nova Era e Guanhães counties, State of Minas Gerais, Brazil, under reforestation with Eucalyptus grandis, were studied. Eight forest sites with soils from different taxonomic classes were selected and detailed mineralogical characterization and evaluation for nutrient reserve potential were conducted in 1991. The soils studied were mineralogically classified as: Kaolinitic-non sesquioxidic (2 and 5); kaolinitic-sesquioxidic (1); gibbsitic-sesquioxidic (4, 6 and 7); hematitic (3) and gibbsitic (8). The main silicate clay […]

In general, farming systems have contributed to highly unstable conditions in agroecosystems, resulting in severe environmental degradation. The present study aims to verify the potential of green manure use in the São Carlos region (SP), as a complementary technique to cropping systems present in the region under investigation, with the objective of improving the quality of its agroecosystems. The region was delimited based on its climate, geomorphology and administrative characteristics, obtained from basic maps and handled through a Geographic Information […]