Volume 30, Number 6, 2006

Soil water content and management systems can promote changes in compressibility parameters. The objective of this research was to study the effects that water content and sugarcane management systems have on the compaction degree and compressibility parameters of a cohesive Yellow Argisol. Four sites were selected in the surroundings of the sugar mill Triunfo, in the state of Alagoas, Brazil; one site with irrigation and a second without irrigation, a third with vinasse application and a fourth under native forest, […]

In precision agriculture management principles must be adapted to the field variability. This requires efficient techniques to estimate and map the spatial and/or temporary variability of soil attributes and properties. However, the determination of some variables that characterize the properties of a particular soil is often onerous and troublesome. In these situations it is interesting to estimate such variables as a function of others that present good space correlation with the forner and are of simpler determination. This is possible […]

Practices of pre-harvest burning and the application of vinasse and N fertilizer are common in sugarcane cultivation. However, results of few long-term studies have been published. This study carried in sugarcane plantations of Cruangi sugar mill, Timbaúba, state of Pernambuco, Brazil, located in the semi-arid-wet transition region of the State aimed at studying the effects of vinasse (80 m3 ha-1) and nitrogen fertilizer (N – 80 kg ha-1) and two harvesting systems (with or without pre-harvest burning) on sugarcane yield […]

A population consists of individuals and a correct sampling of the individuals estimates population characteristics adequately. However, to evaluate soil fertility, what would be the soil individual (sample units), and of what size? The objective of this study was to determine the dimension of the individual soil component of a particular population, in three sampling areas: under no-till or under conventional tillage before or after plowing, and to evaluate soil fertility and develop a soil sampling method, determining the number […]

In no-tillage systems, crop residues and nutrients, namely phosphorus and calcium, accumulate in soil surface and can inactivate soil aluminum. In this way, only the presence of this element in soil analysis does not indicate plant toxicity, since organic and inorganic anions may affect the free aluminum dynamics by decreasing its activity in the soil solution. Knowledge on ion activity and speciation in soil solution is therefore useful to understand Al dynamics. Ionic activity and speciation were determined in the […]

The majority of N from mineral fertilizers and cover crops is usually not used by the very next corn crop, but can be absorbed by follow-up crops. The objective of this study was to evaluate the use of residual nitrogen from urea, sunnhemp (Crotalaria juncea) and millet (Pennisetum americanum) labeled with 15N, applied to no-tillage corn in the previous growing season, in a Red Latosol of the Cerrado. The study was conducted in an experimental farm of the Sao Paulo […]

Liming and organic fertilizers can reduce P adsorption/precipitation in the soil, increasing the availability for plant uptake. To evaluate the effect of liming and cattle manure on phosphorus adsorption in the soil, four experiments were conducted in an entirely randomized design, in a 4 x 5 factorial layout with four replications, in a greenhouse. The treatments consisted of four liming levels (0; 0,5; 1 and 2 times the recommended dose to reach V = 60%) and five doses of cattle […]

The Ca/Al ratio is determinant for root deepening in the soil subsurface layer. Liming this layer can improve root growth and nutrient absorption. Thus, a greenhouse trial was carried out using soil columns. Two varieties of coffee plants (Catuaí and Icatú), one Al-sensitive and the other Al-tolerant, respectively, were evaluated in limed and surface-fertilized soil, whereas 0.0; 0.49; 1.7; 2.9; 4.1; 6.6 and 9.3 t ha-1 of limestone were applied to the subsurface soil. Plants were cultivated for 6.5 months […]

Brazilian soils, especially in the Cerrado region, are highly weathered and poor in some cationic micronutrients in the soil solution. Diffusion is the main transport mechanism to the root surface. The adoption of management practices such as the use of green manures might favor the diffusive flux (DF) and availability of micronutrients to plants. The present experiment aimed to evaluate the effect of incorporation of two distinct green manures into a clayey Red Latosol (LV, Typic Haplustox) on the DF […]

The objective of the present study was to make the physical and chemical characterization of soils developed on sediments of the Barreiras group, in southern Bahia, as well as soils formed from rocks of the crystalline basement, which were taken as reference. For this purpose, soil horizon samples from two representative toposequences of the Coastal Plain were selected and analyzed: (1) eutrophic argisolic Red Latosol, latosolic dystrophic Yellow Argisol, duric orthic Ferrocarbic Spodosol; (2) dystrophic abruptic Yellow Argisol, dystrophic typic […]