Volume 23, Number 1, 1999

Two axial experiments were carried out in two soils of the Northeast of Brazil from 1987 to 1992 to study the response of coconut to urea, simple superphosphate and potassium chloride. Nitrogen was found to affect the number of fruit in the Quartz Sand Soil. The critical level for nitrogen in leaf 14 was 17.18 g kg-1 which was reached when 1.538 kg of N was applied per plant/year. In the same soil, simple superphosphate did not influence the number of fruit while […]

The changes in some soil chemical properties, bulk density, and microbiological activity due to the replacement of a native forest by orange cultivation were evaluated in an Yellow-Red Podzolic Soil. The study was conducted at the Cambuhy orange farm, Matão (SP) in April, 1996. Two areas were selected: (a) a native forest, and (b) a 15-year-old orange plantation. Ten sites were randomly selected in each area and soil samples were taken at 0-20 and 20-40 cm depths. In the cultivated area, […]

The suitability of four extraction methods (acetic acid 0.5 mol L-1, buffer pH 4.0, calcium chloride 0.0025 mol L-1 and water) for estimating the amount of available Si in soil for upland rice was determined. Four soil types corresponding to the following classes were used: Typic Acrustox – isohyperthermic (LEa), Typic Acrustox – isohyperthermic (LVa), Rhodic Acrustox – isohyperthermic (LRd) and Ustoxic Quartzipsammentic – isohyperthermic (AQa), all of them from the Triângulo Mineiro region in Minas Gerais, Brazil. Five Si levels were created in each […]

This study was conducted to characterize the morphology, physics, chemistry, mineralogy and pedography of soil profiles with Mollic horizon at Nazaré da Mata, Pernambuco, Brazil, 1995. Three soil profiles involving Litosol, Reddish Brunizém and Red Yellow Podzolic were morphologically described. Samples were taken from each horizon to determine the physical, chemical (including humic fraction quantification), mineralogical and pedographycal properties. Based on soil properties and environmental conditions, it could be assumed that the surface horizons were developed from climate – vegetation […]

A field experiment of soil and water losses by erosion was carried out during six consecutive agricultural years (1973/74 to 1978/79) at the Experimental Center of Campinas, Instituto Agronomico of São Paulo, Brazil, in a Typic Haplorthox, to evaluate soil loss ratio (SLR) for three green manures: Crotalaria juncea L., Stizolobium aterrinum Piper et Tracy and Dolichos lablab L. Four cropstage periods were defined as isolated periods (0-30, 30-60, 60-90, and 60-120 days after planting), and as accumulated cropstage period (0-30, […]

A soybean trial using a sample of Dark-Red distrophic medium texture Latosol was carried out under greenhouse conditions at the Escola Superior de Agricultura ‘Luiz de Queiroz’ in Piracicaba, São Paulo, Brazil, from December 1993 to July 1994, to evalvate the effects of subsurface compaction and the application of gypsum on nitrogen and phosphorus levels of soybean shoots. A scheme in a bloc randonized desdign, with treatments arranged in a 4 x 4 factorial, with four replications, corresponding to the soil surface […]

The study of root distribution in soils is an adequate method to detect adverse conditions to root development, and evaluate the effect of soil alterations caused by soil management systems. With these objectives, a field experiment was carried out for five years on a Paleudult soil with oat + clover/maize under conventional tillage, reduced tillage and no tillage. To observe the structural modifications of the soil, an adaptation of the “profil cultural” method, was used along with the determination of […]

Losses of nutrients and organic matter due to hydric erosion are highly affected by soil management. Inadequate management systems may cause pollution and eutrophication of surface waters, fertilization cost increase, and ecosystems degradation. Nutrient and organic matter losses due to erosion were evaluated during six years on a very clayey Dusky Red Latosol, with a 0.03 m m-1 slope at Dourados, Mato Grosso do Sul, Brazil under natural rainfall conditions, and different soil management systems. The treatments applied in the crop succession […]

Soil heterogeneity is known to cause variability of soil-water storage. Thus intensive sampling is required to characterize its spatial pattern. For irrigation management, it is necessary to measure the soil water content between irrigations. The objectives of this paper are to identify whether spatial patterns of soil water content in sprinkler irrigated area present temporal stability and whether this property presents spatial dependence. Temporal stability of spatial dependence structures and spatial correlation with clay content were studied. A 180 m long […]

Bulk density is a soil parameter that can be easily measured, associated to other intrinsic soil properties such as texture and organic matter. Pore size distribution, soil resistance to root penetration, and available water are also related with bulk density. When comparing tillage systems, bulk density is frequently used. However, tillage and plant effects on bulk density variability have not been addressed. Bulk density variability is caused by traffic, wetting and drying processes, as well as root system activity. The […]