HORIZONTAL SOIL SAMPLING TO ASSESS THE VERTICAL MOVEMENT OF AGRICHEMICALS

In soils, solutes move most often in ''fingers'' rather than as a unif orm front. Vertical cores can miss paths of preferential flow, resulti ng in inaccurate estimates of chemical concentrations at a given depth . To minimize this problem, a technique for taking undisturbed, horizo ntal soil cores was developed. By comparing entrance and exit holes, i t was found that this technique could be used to obtain cores within s et limits parallel to the soil surface and in the same vertical plain. Using parameters of semivariograms, the number and spacing of vertica l cores required to provide information equivalent to one horizontal c ore was determined.