Volume 28, Number 6, 2004

The intensive use of machines and agricultural equipments in the northeastearn São Paulo State has contributed to increase the areas with compaction problems, probably due to the absence of a well-defined operation chronogram or of models capable of predicting the soil support capacity. This study was conducted in Guariba (SP), with the objective of evaluating the spatial variability of the penetration resistance, soil moisture, and bulk density of a Oxisol (rhodic Eutrustox) under sugar-cane cultivation. The soils were sampled at […]

Increment in pasture productivity has been associated with the understanding of the soil behavior under compression. The objective of this research was to quantify (a) the compression curves and (b) the preconsolidation pressure of the soils under non-irrigated and irrigated short duration grazing systems. Ninety-six undisturbed soil samples were taken from the four successive pasture cycles of Tanzania grass (Panicum maximum Jacq.) in a Hapludalf. The samples were saturated in water and equilibrated at the matrix potential (y): -10 kPa and then […]

Despite relatively high levels of total P, most deeply-weathered tropical soils have very low levels of available P due to the low solubility of most P forms found in these soils. In this research we studied P adsorption of soils, some of which were rich in apatite, developed from basic to ultrabasic volcanic rocks in the Upper Paranaíba region of Minas Gerais State, in relation to the specific surface and clay mineralogy. Samples of eleven B horizons from representative Latosols […]

Copper and zinc adsorption is one of the main phenomena controlling the availability of these metals to plants. As a consequence, studies on the adsorption of such elements in soils may be useful tools to understand the relationship between soil characteristics and retention of these micronutrients. The present study examined the adsorption of copper and zinc in six Latosols (Oxisols) with a wide range of chemical properties. Solutions containing different Cu and Zn concentrations (0, 10, 20, 40, 60, 80, […]

Soybean can be a viable alternative crop for lowlands. However, soybean relies on biological nitrogen fixation, a process that is normally affected by soil flooding, depending on the macrosymbiont genotype. Moreover, the behavior of different bradyrhizobia strains in flooded soil is yet unknown. The present research aimed to evaluate the efficiency of Bradyrhizobium elkanii and Bradyrhizobium japonicum strains recommended for soybean in comparison to mineral nitrogen fertilization, in flooded soil. The experiment was carried out in a greenhouse, where soybean […]

The potential of soil microbial biomass measurements as indicators of soil bioactivity and interferences in this environment can be verified by the amount of published papers on the subject. Nevertheless, a comparison among data from different authors, regions, and soils is only possible when the methodology employed in the determinations is the same. Several papers, however, propose different methodologies and calculations. This study evaluated the results of microbial carbon determination by different extraction and digestion methodologies in two distinct soils. […]

Three greenhouse trials were carried out to verify if rhizobacteria can promote citrus plant growth. Ten isolates of fluorescent Pseudomonads, thirteen of Bacillus spp. and seven of other rhizospheric bacteria were tested in three rootstocks seedlings: ‘Cleopatra’ mandarin (Citrus reshni), rangpure lime (Citrus limonia) and Volkamerian lemon (Citrus volkameriana). Depending on the rootstock, seven Pseudomonads, one isolate of Bacillus and one of other rhizospheric bacteria increased the root or shoot dry weight, indicating a high proportion of growth promoters among […]

Four experiments were conducted simultaneously in a Alluvial Soil, a Low-Humic Gley, a Humic Gley and an artificially drained bog soil with the objective of evaluating the influence of liming and manure applied in previous bean crop on residual effects of phosphorus fertilization, extractor efficiency and acid phosphatase activity in aired soils before flooding in the prediction of P availability to rice cultivated after flooding. After the bean harvest, replicates of each treatment for each soil were mixed and 3.2 kg […]

The effects of liming rates on growth and heart-of-palm yield of peach palm plants (Bactris gasipaes Kunth) were studied in a two-year field experiment conducted in Pariquera-Açu, State of Sao Paulo, Brazil. Soils in this region are allic (sub group Ultic Haplorthox), with base saturation ranging from 15 to 26 % of the cation exchange capacity (CEC). A randomized complete block design, with five rates of dolomitic limestone (0, 0.7, 4.7, 8.7, and 14.6 Mg ha-1) and five replications was utilized. Individual plots were […]

The spatial variability of physical and chemical attributes of Latosols (Oxisols) cultivated with sugarcane was assessed. The study was carried out in a 90 ha area in the surroundings of Jaboticabal, São Paulo State, Brazil (21 º 15 ‘ S and 48 º 18 ‘ W). A 50 m regular grid was projected onto the experimental area. Soil samples were obtained at each 50 m grid point (421 points) from the 0 to 0.20 m and from the 0.60-0.80 m soil layers. Organic matter, pH, P, K+, Ca2+, Mg2+, H + Al, CEC, soil […]