Horizontal and vertical variability of soil parameters and their influence on the behaviour of pesticides in arable land
1991
Bunte, D. (Biologische Bundesanstalt fuer Land- und Forstwirtschaft, Braunschweig (Germany). Inst. fuer Unkrautforschung) | Pestemer, W.
To determine the horizontal variability of soil properties and their influence on the behaviour of pesticides in soil, two different field sites (loamy and sandy oil) were sampled in a 28 and 25 m grid, respectively, and soil parameters (water content, pH value, organic carbon content) and the sorption coefficient (Kd value) of simazine were determined. Detailed studies of the vertical variability of the soil properties and the degradation behaviour of simazine were also carried out on 100 square metre plots at each site. With regard to the horizontal variability, the loamy soil was considerably more homogenous than the sandy soil (coefficients of variation for organic carbon content and Kd value below 35 per cent and over 70 percent, respectively). In case of the sandy soil, in both horizontal and vertical direction, a close relationship was found between organic carbon content and Kd value, which was less marked for the loamy soil presumably because of its higher clay content. The time for 50 per cent disappearance of simazine was 45 days for the loamy soil and 35 to 75 days for the sandy soil. To estimate the effects of spatial variability on the degradation and sorption behaviour of pesticides, simulation of these processes were run for separated homogenous sections of the sandy field site which showed a wide range of persistence and leaching depths depending on the soil properties
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