SPATIAL SERIES ANALYSIS OF HORIZONTAL CORES TO CHARACTERIZE TRACER PATTERNS IN SOIL PROFILES

Surface topography, plant canopy, plant root distribution, and soil pr eferential flow paths cause variability in downward movement of agrich emicals in soil. To better understand this variability, tracers are of ten applied to the soil surface and their signatures (concentration pa tterns) are examined, To characterize Br- signatures within a Crete si lt loam soil (fine, montmorillonitic, mesic Pachic Argiustoll), potass ium bromide was applied to the soil surface at 200 kg ha(-1). Four set s (two sets in June and two sets in August) of four 6.1-m horizontal c ores were taken in a vertical plane, perpendicular to corn plant rows at 20-, 40-, 80-, and 120-cm depths, Each 6.1-m core was divided into 120 5.1-cm sections and analyzed for Br-. Spatial series analyses were used to identify deterministic and combined deterministic-stochastic models that described the cyclic nature of Br- concentrations at each depth, Periods for these sinusoidal cycles generally corresponded to t he distance between plant rows or the distance between the wheel track s of field equipment.