ABSTRACT The overloading of soil with manure or mineral fertilizers enhances phosphorus (P) availability, promoting its loss to water bodies and increasing the risk of eutrophication. In this sense, the establishment of an environmental P threshold is a simple and useful tool to classify soils regards its risk of P losses. Here we propose a P-threshold for soils from the state of Rio Grande do Sul (RS) in Brazil, with the soil clay content as the principal variable of the […]

It has been found that the results of the land use and management techniques adopted for soils derived from Caiuá sandstone in the Northwest of Paraná are not always satisfactory in terms of crop yields. In this region, sandstone occurs in two forms: the Caiuá and Paranavaí Formations, with differences in soil particle size. We hypothesized that the water retention and availability for agricultural production is lower in the Caiuá soils, due to the higher proportion of coarse sand than […]

Since the 70s, spectroscopic techniques, especially those with infrared radiation (NIRS -Near Infrared Spectroscopy and DRIFTS – Diffuse Reflectance Fourier Transformed Spectroscopy) have been proposed for inorganic soil analysis, but only few methods found routine use in Brazil so far. This fact is probably due to the difficulty in building calibration models based on multivariate tools with real soil samples that have a complex composition that varies geographically and according to the management. The objective of this study was to […]

Macroscale soil behavior depends on the mechanical properties of individual aggregates. Tensile strength (TS) of soil aggregates has been used as an indicator of management effect on soil quality as related to land use. The objective of this study was to evaluate the change of TS in relation to the variation of soil organic carbon (SOC) content in two soils (Typic Hapludox) with different textures under a long term no-tillage system. The experiment was arranged in a completely randomized 2 […]

The porosity of the clay fraction is very important for the understanding of the physicochemical phenomena which are relate to the specific surface area of solid particles. The specific surface area (SBET) and porosity of clay fractions of two Rhodic Ferralsols in the state of Mato Grosso do Sul, Brazil, natural kaolinite (KGa2), synthetic goethite (Gt) and hematite (Hm) were evaluated through adsorption and desorption isotherms of N2.. Results concerning SBET and particle porosity were related to the maximum P […]

The accuracy of mechanical analysis depends on the complete dispersion and stability of the soil suspension in order to make the separation of the soil fractions possible. The purpose of this study was to evaluate the efficacy of adding sand in different amounts and particle sizes in the dispersion phase of the soil textural analysis in attempt to improve the accuracy of results. The soils used were Rhodic Eutrudox (oxidic) (LVef), Anionic Rhodic Acrudox (LVwf), Rhodic Eutrudox (kaolinitic) (LVe), Arenic […]

Pedotransfer functions (PTFs) are useful tools to obtain estimates of soil physical properties such as the soil water retention curve (SWRC) and the soil resistance to penetration curve (SRPC), which are important inherent soil properties and difficult to measure. Most of the studies in the literature report PTFs only in relation to SWRC estimates. An important and necessary advance in this research area would be the development of PTFs for a simultaneous estimation of the SWRC and SRPC, which is […]

The degree of soil nutrient availability to plants is one of the major factors determining crop production. Mathematical models have been proposed to simulate nutrient flux toward roots, taking into account several physical and chemical soil parameters as well as anatomical and physiological root traits. The objective of this paper was to establish a relationship between Baldwin’s theoretical diffusion model and experimental field data involving the response of wheat to K fertilization. Based on simulations with the theoretical model, it […]

The aim of this study was to evaluate the behavior of the soil line for different soil classes by using reflectance data with a spectroradiometer in the laboratory. Representative samples of the surface and subsurface horizons of 18 soil classes collected in a pilot area in Rafard county, southwest São Paulo state, were dried, sieved and accomodated for spectral reading. Data were computed in order to simulate TM-Landsat 3 and 4 bands and to draw the graphs. The findings showed […]

Samples of 30 soils were taken with the objective of characterizing the Capacity Factor of Phosphorus (CFP) and its relation with several properties of soils of Entre Ríos, Argentina. Isotherms of adsorption and a quick test of P adsorption were estimated. Langmuir and Freundlich equations described the adsorption phenomenon satisfactorily. The maximum adsorption capacity varied between 46 and 716 mg kg-1 of P in the soil, considering that the soils analyzed have from medium to low CFP. The adsorption capacity […]