Volume 24, Number 3, 2000

Soil water infiltration rate, together with rainfall rates determine runoff rates, being an important parameter for erosion estimation and soil conservation studies. Measurement of infiltration rates can be performed using a double-cylinder device (CD) or a rotating-boom rainfall simulator (RS). The use of CD is less laborious in comparison with RS instruments, but results often do not agree with rates occurring in real rainfall situations, possibly due to surface crust formation. Crust formation depends both on factors that do not […]

The term soil compaction refers to the compression of an unsaturated soil during which an increase of the bulk density of soil occurs in consequence of the reduction of its volume, due to the expulsion of the air caused by inadequate management. To study the effect of different soil management systems on maximum dry bulk density and optimum moisture content, an experiment was conducted in a Dusky Red Latosol of the Lavras (MG, Brazil) region, submitted to the following management […]

This study evaluated the molecular weight (mw) as well as the proportions of humic and fulvic acid fractions in humic substances (H5) extracted with 0.1 M NaOH and a chelating (Chelex 100 chelating ion exchange resins) (Na form), via High-Performance Size Exclusion Chromatography (HPSEC). Samples of a Dusky Red Latosol were collected from three areas: under orange-cultivated forest with and without liming. Standards of sodium polystyrene sulfonate and acetone were used to calibrate the molecular weight and retention time ratio. […]

In order to be used in a program of inoculation, efficient arbuscular mycorrhizal fungi (AMF) must be able to cope with the indigeneous fungal population. An experiment was conducted under greenhouse conditions at the Embrapa Cassava and Fruit Crops in Cruz das Almas (BA), Brazil, with the objective to evaluate the competitive capability of selected fungi, using natural soil with Tainung no. 1 variety. A Yellow Oxisol with 3 mg dm-3 of available P was used. Three exotic and three […]

Soybean [Glycine max (L.) Merrill] plants establish a symbiosis with bacteria belonging to the genus Bradyrhizobium, realizing the biological N2 fixation process. The inoculation with selected rhizobial strains guarantees the maximization of the biological process. In Brazil, almost 13 million doses of inoculants, mainly peat based, are commercialized annually. However, the peat adhesion to the soybean seeds is low, requiring the use of adhesives. The current recommendation is the use of a water sugar cane solution at 25%, but this […]

Soybean [Glycine max (L.) Merrill] inoculation and reinoculation are essential to guarantee the maximization of the biological N2 fixation process. Most inoculants commercialized for soybean in Brazil are peat-based, but there are doubts about the dose of peat inoculant which should be recommended, specially under stressing conditions or in areas previously inoculated. Therefore, for the central region of Brazil, the recommendation is 1.000 g of inoculant/50 kg of seeds, with a sugar cane solution as adhesive. However, in this study […]

The existence of soil exchangeable Al in toxic levels inhibits root growth and elongation, with negative effects on water and nutrient uptake, especially of P. Thus, as soil P increases, plants become less dependent on a large root system, that may decrease crop response to liming. This study was carried out to evaluate the effect of liming and phosphorus fertilization on corn yield. The experiment was conducted in Lages, Southern Brazil, from 1994 to 1998, in a clayed Oxisol (Hapludox) […]

The aim of this work was to evaluate the influence of seed pelleting with lime and with ‘Magnesian Thermophosphate’ on ionic absorption of three sorghum genotypes (Sorghum bicolor (L.) Moench), cv BRS 701, BRS 304 e BRS 601. Pelletized and non-pelletized seeds were germinated during eight days at room temperature. After this period, eight plants with uniform root and shoot development, from each treatment, were transferred to a Hoagland solution. Phosphorus and potassium absorption parameters were determined after 20 days. […]

The use of mineral fertilizers and legumes is the most important strategy used to supply nitrogen for cash crops. Since there is a risk of environmental pollution by nitrogen fertilization, it is very important to improve the approaches of nitrogen use recommendation to achieve sustainable agricultural practices. The organic matter content has been used as a parameter to estimate N availability, but in some cases it has been inefficient. In order to develop an equation to estimate N availability in […]

An experiment was carried out under greenhouse conditions at the Soil Science Department of the Universidade Federal de Lavras, Minas Gerais, Brazil, to determine critical levels of different phophorus fractions and acid phosphatase activity in bean plants (Phaseolus vulgaris L. cv. Carioca-MG); the relationship between these fractions and the acid phosphatase activity and grain production, and the relationship between acid phosphatase activity determined “in vivo” and “in vitro“. The plants were cultivated on four lowland soils of southern Minas Gerais, […]