The horizontal movement of seeds in arable soil by different soil cultivation methods.
Abstract
To assess the impact of soil cultivation on the horizontal movement of seeds in arable soil, plastic beads and barley or triticale seeds were used as seed models. Different coloured beads were introduced in the field immediately before each of five cultivations: ploughing, two tine cultivations, harrowing and seed drilling. Beads were recovered from 20-cm soil cores divided into four 5-cm deep soil horizons. After a typical cultivation sequence of five operations, beads were found up to 15 m from their source, although most beads were found within 2 m. Most beads were recovered from the surface 5 cm of the soil profile, except for those introduced onto the surface or at 20 cm depth before ploughing, which were concentrated below 10 cm. Regression analysis was used to determine the pattern of bead movement by seed drilling. A novel analysis using Fast Fourier Transforms established the probability distribution functions of the remaining cultivation operations for horizontal movement. Using the final seed distributions, the effects of each cultivation were sequentially deconvoluted and the probability distribution functions smoothed. The proportions of beads moved were also calculated. Ploughing and seed drilling moved seed the least distance compared with other cultivations. The mean distances moved were 0.36 m and 0.26 m, respectively. Tine cultivations moved beads 0.71 m and 1.21 m, while harrowing moved seed a mean distance of 1.58 m. It is concluded that cultivation sequences based on ploughing are likely to limit seed movement in soil. The Fourier deconvolution approach has potential for predicting future seed distributions and thus the spatial behaviour of weed patches within fields.