Mechanical impedance of clayey and gravelly soils is often needed to interpret experimental results from tillage and other field experiments. Its measurement is difficult with manual and hydraulic penetrometers, which often bend or break in such soils. The purpose of this study was to evaluate the feasibility of a hand-operated “Stolf” impact penetrometer to measure mechanical impedance (soil resistance). The research was conducted in Raleigh, North Carolina, USA (35o 45’N, 78o 42’W, elevation 75 m). Corn was planted on April […]

The experiment was conducted under greenhouse conditions at the Federal University of Uberlândia, State of Minas Gerais, Brazil, from March to August 1995. The purpose of this study was to determine if suppression of seven soil classes could inhibit infection of soybeans by R. solani, and how suppression might relate to the physical, chemical and biological characteristics of these soils. After infesting soils with R. solani, grown on autoclaved sorghum grains, disease intensity increased in soybean seedlings grown in all […]

The effects of continuous sugarcane cropping on the chemical 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, State of Alagoas, Brazil, 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 samples were taken from each horizon to determine pH (H2O […]

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), […]

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 […]

Despite the fact that aluminum toxicity to crops is eliminated near soil water pH of 5.5, lime recommendation in many regions aims to increase soil pH up to 6.0 or even higher. For highly buffered soils, high rates of limestone are required to raise the pH from 5.5 to 6.0, resulting in additional, sometimes unnecessary, costs. The objective of this study was to evaluate the effect of soil pH on corn yield in a very acid Hapludox. The experiment was […]

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), […]