Volume 38, Number 4, 2014

The increase of organic acids in soils can reduce phosphorus sorption. The objective of the study was to evaluate the competitive sorption of P and citrate in clayey and sandy loam soils, using a stirred-flow system. Three experiments were performed with soil samples (0-20 cm layer) of clayey (RYL-cl) and sandy loam (RYL-sl) Red Yellow Latosols (Oxisols). In the first study, the treatments were arranged in a 2 × 5 factorial design, with two soil types and five combinations of […]

The electrical charges in soil particles are divided into structural or permanent charges and variable charges. Permanent charges develop on the soil particle surface by isomorphic substitution. Variable charges arise from dissociation and association of protons (H+), protonation or deprotonation, and specific adsorption of cations and anions. The aim of this study was to quantify the permanent charges and variable charges of Reference Soils of the State of Pernambuco, Brazil. To do so, 24 subsurface profiles from different regions (nine […]

Selection of common bean (Phaseolus vulgaris L.) cultivars with enhanced root growth would be a strategy for increasing P uptake and grain yield in tropical soils, but the strong plasticity of root traits may compromise their inclusion in breeding programs. The aim of this study was to evaluate the magnitude of the genotypic variability of root traits in common bean plants at two ontogenetic stages and two soil P levels. Twenty-four common bean genotypes, comprising the four growth habits that […]

In the southern highland (Planalto Sul) region of Santa Catarina, Brazil, most of the pine forests were planted without soil fertilization. Currently, many areas are in the second or third rotation, and their productivity may be limited by low soil fertility. An alternative to mitigate this problem would be fertilization in the established forest. This study was carried out with the objective of evaluating the effect of fertilization with N, P, and K at different growth stages of Pinus taeda. […]

Different yield potentials between plots and within them have been verified in areas managed under no-till (NT). Precision farming (PF) techniques can help in identifying these distinct areas, but for efficient soil fertility management in areas under long-term NT, there must be representative sampling. The aim of this study was to evaluate the influence of soil chemical properties on wheat yield in accordance with the sampling layer or depth in an area under long-term NT using zones of a plot […]

A form of increasing the efficiency of N fertilizer is by coating urea with polymers to reduce ammonia volatilization. The aim of this study was to evaluate the effect of polymer-coated urea on the control of ammonia volatilization, yield and nutritional characteristics of maize. The experiment was carried out during one maize growing cycle in 2009/10 on a Geric Ferralsol, inUberlândia, MG, Brazil. Nitrogen fertilizers were applied as topdressing on the soil surface in the following urea treatments: polymer-coated urea […]

Brazil is the fourth largest consumer of fertilizers in the world. Among these, bulk blends fertilizers are the most consumed in the country. After updating of Brazilian legislation in regard to fertilizers in 2004, many producers claim that there was an excessive increase in the strictness of legislation concerning inspection of nutrient levels in those products. Within this context, the objective of this study was to provide an exploratory and descriptive statistical analysis to the data gathered by MAPA (Ministry […]

Based on the assumption that silicate application can raise soil P availability for crops, the aim of this research was to compare the effect of silicate application on soil P desorption with that of liming, in evaluations based on two extractors and plant growth. The experiment was carried out in randomized blocks with four replications, in a 3 × 3 × 5 factorial design, in which three soil types, three P rates, and four soil acidity correctives were evaluated in […]

In regions with a tropical climate, the greatest limitations for straw maintenance on the soil surface are difficulties on its establishment and high rates of decomposition. With the aim of identifying the productive potential of Xaraes and Ruziziensis grasses, as well as subsequent straw formation for continuity of the no-tillage system, the following factors were evaluated: the dry matter yield, the lignin/total N ratio, macronutrient accumulation, and straw decomposition in two growing seasons. The treatments consisted of two Brachiaria species […]

Frequently, soil compaction limits the yield of grain crops in mechanized lands, and its spatial distribution in the cropland is usually regionalized. In an area managed under long-term no-tillage, we investigated the relationship between soil penetration resistance (PR) and soybean yield, the effectiveness of types of chisel plows, and their effect on soybean yield. The soil from the plateau region of the state of Rio Grande do Sul, Brazil, was classified as a clayey Oxisol. The climate is subtropical (Cfa […]