Variabilidade e distribuição da resistência do solo à penetração em latossolo amarelo distrocoeso

Abstract

With the increase of mechanization in agricultural practices, resulting in high soil compaction, which added to the cohesive layer present in Coastal Trays, results in a high soil penetration resistance (RP) limiting root growth. The present work had objective to evaluate the PR variability, using the Stolf impact penetrometer, with the purpose of generating spatial distribution maps and estimating the minimum number of sampling points to determine the PR, in a Distrocoeso Yellow Latosol, located in the Experimental Field. of the Center for Genetic and Biotechnological Improvement (NBIO) of the Federal University of Recôncavo da Bahia (UFRB), located in Cruz das Almas-Ba. An area of 4,000 m2 was analyzed, determining the PR in a 10 x 10 m sampling grid at depths of 0.0-0.10, 0.10-0.20, 0.20-0.30 and 0, 30-0.40 m, totaling 55 points. Then PR was corrected to 100 KPa U, recommended for cohesive soils. Thus, the statistical analysis was applied, resulting in the coefficient of variation (CV), used as a basis to calculate the minimum number of sampling points needed to evaluate the PR, in the variation percentages of 5, 10, 15, 20, 25 and 30% around the average, and for the 5% probability level. Soil PR variability was very high in the evaluated area for all depths with base on CV. The management systems adopted in the area influenced the physical attributes of the soil, resulting in an increase of density, with consequent reduction of macropore volume and increase of micropores in the depth of 0.20-0.40 m. Being the granulometry another indicator of the cohesiveness of the soil. From the PR data plotted on the maps for the depths of 0-0.10 m, 0.10-0.20 m, 0.20-0.30 m and 0.30–0.40 m it is possible to promote a better visualization of the degree of compaction of the area and determine management practices that enable a reduction in PR. The best representatives of the minimum soil PR points for the evaluated depths occurred from 16 to 26 for an acceptable error of 10%.