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 […]

This experiment was carried out in Santa Barbara county, Minas Gerais State, Brazil to evaluate the effect of plant population (PP) on nutrient accumulation and distribution in Eucalyptus grandis. Plant population varied from 500 to 5,000 trees ha-1, laid out in a randomized block design with three replicates. The assessments were performed when the trees were 31 month-old, by sampling tissues from the above ground components of an average tree per plot, forest floor, and soil to the depth of […]

Information about availability of boron in the Brazilian semi-arid soils is scarce. A greenhouse assay was conducted with 29 superficial samples (0-20 cm) obtained from representative mapped soils of the State of Ceará, Brazil, using sunflower as an indicator. The experiment was performed in 2.5 kg pots containing soil, fertilized with two boron levels (0 and 1.5 mg kg-1) with three replicates per treatment. The boron availability in the soil was determined by hot water, 0.05 mol L-1 hydrochloric acid […]

The experiment was carried out in greenhouse at the Soil Science Departament – Federal University of Lavras, Minas Gerais, Brazil. The objective was to study the effects of different CaSO4/CaCO3 ratios on the movement of nutrients in soil and cotton growth. The treatments consisted of four CaSO4/CaCO3 percentage ratios (100/0, 75/25, 50/50, 25/75 and 0/100), in an equivalent basis. A control treatment, without application of either CaSO4 or CaCO3, was also established. Substantial calcium and sulfate movement downwards was observed […]

The kinetic constants Kmapp and Vmaxapp of phosphatase activity from a coastal tableland soil grown with orange trees, submitted to different base saturation levels (32.0; 45.0; 64.0 and 76.6%), were determined. These determinations were made in optimum pH values for alkaline and acid phosphatases and in the pH values obtained for each base saturation level. Phosphatase activity has followed Michaelis-Menten kinetics, regardless the soil base saturation levels or pH values used for enzymatic activity evaluation. Increases in the soil bases […]

The effects of the application of pure grade CaF2 and CaCO3 on the concentration of Al and other chemical elements in the percolated solution of acid soil samples, collected over an eight month period, were evaluated in a greenhouse experiment in Piracicaba county, State of São Paulo, Brazil. The pH values increased in the percolated solution of soil samples that received both CaCO3 and CaF2. The CaF2 treatments were more efficient than CaCO3 treatments on the withdrawal of Al from […]

The aim of this experiment was to evaluate the nitrogen of the microbial biomass under different soil management systems by the fumigation-incubation (FI) and fumigation-extraction (FE) methods. Soil samples were collected in four seasons, during one year, from a Paleudult soil in the Central Depression of Rio Grande do Sul State, Brazil. Soil microbial biomass N was analyzed in soil under three tillages systems (conventional, reduced and direct drilling) and two crop systems: oats (Avena strigosa) + vetch (Vicia sativa)/corn […]

An experiment was carried out in January of 1994 in the greenhouse at the Crop Science Department of the Universidade Federal de Viçosa, State of Minas Gerais, Brazil. The objective of this experiment was to evaluate the effecets of aluminum on P, Ca and Al concentrations in the plants and on the P and Ca efficiencies of utilization by nine coffee genotypes. Plants were grown with 0 and 0.296 mmol L-1 of aluminum in nutrient solution, in pH 4.0, for […]

The effects of soil preparation systems and doses of nitrogen on total dry matter, straw and grain production and on nitrogen accumulation by corn plants (Zea mays L.) cultivated under irrigation were evaluated in a field experiment in a Dark-Red Latosol (Oxisol), originally under cerrado vegetation, at EMBRAPA/CNPMS experimental station, Sete Lagoas, Minas Gerais State, Brazil, from November, 1995 to June, 1996. The soil preparation systems studied were: no till, conventional till with disk plow and conventional till with moldboard […]

The dispersive transport of solutes in soils is described by diffusive equations and by models that assume the existence of a causal relationship between physical characterisitcs of porous media, its water content and the macroscopic manifestation of processes that take place in it. The validity of this proposition, as a criterion in the formulation of process models that govern the transport of solutes in soils, is discussed heuristically. Based on indicators derived from a moment analysis of breakthrough curves (BTCs), […]