OPTIMAL NUMBER OF SAMPLES FOR EVALUATION OF SOIL RESISTANCE TO PENETRATION IN AREA UNDER CULTIVATION OF EUCALYPTUS AND NATIVE FOREST

Abstract

Soil resistance to penetration (RP) is a physical attribute used to quantify soil compaction and the influence of the average representative sample population, causing errors. The objective of this work was to evaluate the RP in distrófico red Latosol under native forest and eucalyptus. Random samples were conducted in groups of 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 and 100 every 0.10 m from the ground up to 0.6 m layer. Average values were calculated from the RP, the confidence interval and the accuracy of the estimate (D), the significance of 0.05. Under the conditions of study it was possible to observe that the population has high reliability, with errors below 10% and that in cultivated area the number of samples needed for evaluation of the RP is greater than to the ground under the Woods.