This experiment was carried out in the Department of Soil Science of the Federal University of Viçosa, Minas Gerais State, Brazil, with the objective of evaluating the effect of P concentration and the duration of the P-omission period on three different fractions of P in Eucalyptus seedlings: i) total soluble P (TSP); ii) inorganic P (IP); and iii) organic P (OP). A solution containing high amount of phosphorus (8 mg L-1 of P) was added to five species of Eucalyptus […]

Utilization of soil erosion models requires data on soil canopy cover and crop height. Equations to describe the relationship of aboveground biomass to soil canopy cover and height of the corn, cotton, dry bean, potato and soybean crops were developed from data collected at farm plots in several municipalities of the State of Paraná during the 94/95 crop year. Canopy cover and height, and aboveground biomass were collected at fifteen-day intervals. Yield was determined by manual harvest. The relations utilized, […]

Increase in soil pH by liming has been considered sufficient to assure Mo availability for crops. In soybean, the high response to liming might be related to additional demand of Mo for nitrogenase complex activity, in relation to other non-nitrogen fixing crops. Therefore, this research planned to study lime-Mo interactions for soybeans and sorghum crops, in a Red-Yellow Podzolic soil from the Mococa Experimental Station, Instituto Agronômico, State of São Paulo, Brazil, during the period 1985 to 1989. The treatments […]

This research was conducted from May to September, 1995, in order to evaluate liming criteria for rice plants on flooded soils of Minas Gerais State, Brazil. The effects of increasing CaCO3 + MgCO3 dosis on dry matter production were evaluated in a greenhouse pot trial. The experimental matrix was a complete factorial with ten lowland soils and five levels of liming. The soil characteristics which significantly affected the lime levels recommended were: titrable acidity at pH 7,0 (H + Al), […]

Since 1986, the occurrence of water repellency has been observed in soil samples collected for soil surveys conducted by the Soil Department of Federal Rural University of Rio de Janeiro (UFRRJ) and by the National Center for Soil Research of EMBRAPA. With the objective of studying the causes of this phenomenon, seven soils were selected and their water repellence rating was determined by two methods: the molarity of ethanol droplets and water drops penetration time. Two methods of extraction were […]

With the objective of evaluating the applicability of Langmuir and Freundlich isotherms to boron adsorption in lowland soils (Gleysol and Cambissol) of Rio de Janeiro State Brazil, 1997, laboratory assays were developed using surface and subsurface soil samples. Retention was evaluated by equilibrating samples with calcium chloride solution 0.01 mol L-1 containing 0.0; 1.0; 2.0; 4.0 and 8.0 mg L-1 of B. The use of Freundlich and Langmuir isotherms resulted in the most suitable fit for experimental data.

Air dried subsurface samples of a heavy textured Red-Yellow Podzolic soil, representative of the industrial solid residue pilot landfill (ISRL) of the National Steel Works (Companhia Siderúrgica Nacional-CSN), were packed in 5.4 cm width and 37 cm high glass columns. An acid iron smelter residue was placed on the top of the soil columns to make a 4:1 soil-residue ratio, in consonance with the basic CSN project. To evaluate Cr, Mn, Ni, Cu, Zn, Cd and Pb mobilities, the system […]

Iron oxihydroxides form strong chemical bonds with phosphate anions, reducing P availability to plants. The objective of this study, conducted in 1994/95, was to quantify forms of iron oxides in soils from Uruguay, and to study their relationships with phosphorus sorption. Iron oxides extracted with dithionite-citrate-bicarbonate (Fed) from ten soil samples (0-15 cm depth) ranged from 1598 to 8.592 mg kg-1 and were related with their parent material. Poorly ordered Fe-oxihydroxides, extracted by 0.2 mol L-1 ammonium oxalate at pH […]

This research was carried out in Rio Grande do Sul State, Southern Brazil, during the 1990/1991 summer harvest. The main objective was to evaluate the aggregation and aggregate stability of two clayey soils classified as Dusky Latosol (Haplorthox) and Dark-Red Podzolic (Paleoudult). Two treatments were used in the Haplorthox: grass (Setaria anceps L.); and crop rotation under conventional tillage (wheat (Triticum aestivum) soybean (Glycine max L.)). On the other hand, four treatments were used in the Paleoudult: grass (Digitaria decumbens […]

Hematites from nine soils and one from itabirite rock were concentrated with 5 mol L-1 NaOH, and analyzed by XRD (step scanning 0.02o2θ/20 s), to determine the unit cell parameters. The samples were dissolved by extraction with DCB to determine the Fe (Fed) and Al (Ald) content. Al substitution was estimated from a0 using established regressions currently in use based on hematites synthesized at 25°C (Al25) and 70°C (Al70). The a0 values ranged from 0.50380 to 0.50200 nm, corresponding to […]