Volume 27, Number 1, 2003

Aluminum (Al) is one of the most abundant elements in weight in Brazilian soils, found in different minerals and forms. Considering the lack of information about its participation in the physical behavior of soil, the present study aimed to evaluate the relationship between the mineralogy of the clay fraction, different forms of Al and physical attributes of different soils. Disturbed and undisturbed samples of A and B horizons of representative soils from the South and Campos das Vertentes physiographic regions […]

Inadequate crop practices are among the main causes for reduced productivity of cashew crops in the Northeast of Brazil. Periodical elimination of vegetation and the use of heavy machines and implements influence soil temperatures and density, possibly affecting plant growthand development. This is an aggravating fact, considering the sandy soils and climate conditions of the region. This study had the objective to investigate the development of cashew nut plants (early-dwarf cultivar) at different levels of soil temperature and density, to […]

There are various methods for assessing data on infiltration rates, but it is important to know how these methods interact with soil properties. The objective of this paper was to analyze four methods for infiltration measurement in different soil types under a no tillage system. Field experiments were performed in Campinas, Campos Novos Paulista and Pindorama, in São Paulo State, on Eutrudox, Hapludox and Hapladult soils, respectively. Infiltration rates were measured from September to November 2000, by the evaluation methods: […]

Soil organic matter from the surface horizon of two Brazilian soils (a Latosol and a Chernosol), in bulk samples (in situ SOM) and in HF-treated samples (SOM), was characterized by elemental analyses, diffuse reflectance (DRIFT) and transmission Fourier transform infrared spectroscopy (T-FTIR). Humic acids (HA), fulvic acids (FA) and humin (HU) isolated from the SOM were characterized additionally by ultraviolet-visible spectroscopy (UV-VIS). After sample oxidation and alkaline treatment, the DRIFT technique proved to be more informative for the detection of […]

The sorbed P/ P in solution relation of the soil may be affected by the previously sorbed P (Ppre) content and by soil management systems. The objective of this study was to evaluate modifications in the maximum P sorption capacity (Pmax) and the constant related to the colloid linkage energy (k) of the Langmuir isotherm caused (a) by the inclusion of Ppre, and (b) by different soil tillage methods and crop sequences. In May 1997, samples of two Oxisols (Very […]

Interactions between P and S anions and soil colloids are significant, mainly those rich in iron and aluminum oxides, whose electric surface charges vary according to the pH and ionic strength of the solution. The objective of this study was the evaluation of phosphate and sulfate adsorption on surface and subsoil samples of a clayey Anionic Acrudox, a medium-textured Anionic Acrudox and a clayey Rhodic Kandiudalf from the northern region of the State of São Paulo, Brazil. Maximum phosphate and […]

Rhizobacteria (PGPR) as plant growth boosters can be an option for increased productivity in several crops, including lettuce. Four assays with rhizobacteria isolates from different origins were carried out to verify their potential for growth enhancement in lettuce. Seventy seven fluorescent pseudomonads, 23 Bacillus, and 11 other rhizospheric bacteria isolates were tested in sterilized sand, in sterilized soil, and in a substrate mixture of soil and cattle manure (1:1, in volume), similar to the mixture used by producers, and in […]

Solarization is a method for soil disinfestation, taking effect by increased soil temperatures under soil covers of transparent polyethylene sheets during the period of intense solar irradiation. Four field experiments were set up in the state of São Paulo, Brazil (districts of Mogi das Cruzes, Jarinú, Piracicaba and Itatiba), in the years 2000 and 2001, to evaluate the effects of soil solarization on physical, chemical and biological soil properties. Solarization caused a significant reduction in penetration resistance of the evaluated […]

In Brazil, Bradyrhizobium inoculation has successfully replaced the use of N fertilizer on soybean [Glycine max (L) Merr.] crops. However, with the expansion of no-tillage cropping systems in the Cerrados region, the idea that it is necessary to use small N rates at the sowing to overcome problems related with N immobilization has become widespread, mainly when soybean is cultivated after a non-legume crop. In this study we examined soybean response to small rates of N fertilizer under no-tillage (NT) […]

The availability of S in soils can be understood by the interplay among the intensity factor, quantity factor and soil S buffering capacity. The quantity factor is the labile nutrient pool, defined as the quantity present in the soil solid phase, capable of dissolving into the soil solution during one growing cycle of a given annual crop. Aiming to develop a quantification method for labile S, three soils samples were incubated for 60 days after the following treatments: (a) non-disinfected […]