A very active and influential parameter in the erosive process is the R factor, called rainfall erosivity. This factor is one of the components of the universal soil loss equation. Studies in spatial variability have been conducted in an attempt to define the spatial distribution of the R factor for a given region. This study aimed to calculate the rainfall erosivity (R factor – EI30) to generate spatial maps. The study was conducted in experimental areas of eucalyptus stands in […]

Knowledge on variations in vertical, horizontal and temporal characteristics of the soil chemical properties under eucalyptus stumps left in the soil is of fundamental importance for the management of subsequent crops. The objective of this work was to evaluate the effect of eucalyptus stumps (ES) left after cutting on the spatial variability of chemical characteristics in a dystrophic Yellow Argisol in the eastern coastal plain region of Brazil. For this purpose, ES left for 31 and 54 months were selected […]

Soil penetration resistance exercises major influence on crop development, root growth and crop productivity, which is inversely proportional to that soil attribute. In this way, the analysis of spatial variability of soil penetration resistance and crop yield based on geostatistics can indicate alternative management practices, not only to reduce the effects of soil variability on crop yield, but also to improve the estimated crop response under certain management practices. This study aimed to correlate soil penetration resistance (RP) and spatial […]

Soil management systems modify the spatial distribution of soil physical properties. The objectives of this study were to verify the spatial dependency and co-relationship of some soil physical properties by data fitting to individual and cross-semivariograms in an Oxisol (Typic Haplorthox) under no-till and conventional tillage, in Campo Mourão, state of Parana, Brazil. In April 2004, 128 undisturbed soil samples were collected in a 3 x 5 m grid, in the middle of the 5-0.15 m layer. The following soil […]

Soil porosity influences plant development since root growth and crop yield are determined by the root depth. The objective of this study was to investigate the linear and spatial variability and correlations between common bean yield and soil porosity. The bean grain yield of the irrigated cultivar Carioca IAC was analyzed in the growing season 2004/2005, in Selviria-MS, as well as macroporosity (MA), microporosity (MI) and total porosity (TP), in a Dystroferric Red Latosol, at four depths: 1 (0.0-0.10 m), 2 (0.10-0.20 m), 3 (0.20-0.30 m) […]

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 […]

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 […]

The objective of this study was to identify site-specific management zones by means of chemical soil fertility indicators on sugarcane-cultivated Latosols (Oxisols), using indicator kriging, aiming an optimized use of precision agriculture techniques. The study was conducted in a 90 ha section of a larger field (1.900 ha) near Jaboticabal, São Paulo State – Brazil (21 ° 15 ‘ S and 48 ° 18 ‘ W). A 50 m regular grid was drawn on the experimental area (300 by 3.000 m). Soil samples were obtained at each 50 m grid point (420 points) from […]

The high spatial variability of the soil hydraulic conductivity as a function of soil water content (or soil-water matric potential) makes the sampling planning and the use or extrapolation of mean values obtained in field studies of soil-water dynamics difficult. In this context, the objective of this study was to verify the temporal stability of soil-water content and soil-water matric potential and to show how the temporal stability methodology can be used as a tool to rationalize the sampling strategy […]

The mechanical penetration resistance of a soil strongly influences plant development since the root growth as well as the crop yield change inversely proportional to its value. The bean grain yield (GY) and the penetration resistance (PR) in a Dystrophic Red Latosol (Rhodic Ustox) located at the Experimental Station of the Faculdade de Engenharia/UNESP in Ilha Solteira county, São Paulo State, Brazil (22 º 23 ‘ latitude S; 51 º 27 ‘ longitude W), were analyzed in the crop year 2001/2002. The main objective was to work out […]