Volume 22, Number 3, 1998

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 […]

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 […]

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 study was carried out using soil samples collected from a Podzol grown with orange trees, at Estação Experimental de Umbaúba, Umbaúba-SE (CPATC-EMBRAPA), to evaluate the acid and alkaline phosphatases activities from a coastal tableland soil submitted to different base saturation values (32, 45, 68 and 76.6%) and the relationships between soil characteristics and these activities. Positive responses to the increment of base saturation were observed for pH, organic matter content, available phosphorus and acid and alkaline phosphatases activities, in […]

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 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 […]

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 […]

Acid phosphatase activity was evaluated in leaf extracts of four year old peach palms (Bactris gasipaes Kunth) in January, 1995. Plants from four progenies were field-grown under the combination of two levels of phosphorus (P1 = 0 and P2 = 200 kg ha-1 year-1 of P2O5) and two levels of nitrogen (N1 = 0 and N2 = 400 kg ha-1 year-1 of N). Potassium was applied at a rate of 200 kg ha-1 year-1 of K2O. The results of acid […]

An experiment was carried out in January of 1994, in the greenhouse of the Crop Science Department of the Universidade Federal de Viçosa, located in the Zona da Mata, State of Minas Gerais, Brazil (651 meter mean altitude) to evaluate the effect of aluminum on growth and development of nine coffee genotypes. Coffee plants with two pairs of fully expanded leaves were submitted to 0 and 0.296 mmol L-1 of aluminum in nutrient solution with pH 4.0 for 115 days. […]

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 […]