Spatial root distribution and water uptake of maize grown on field with subsoil compaction
Soil compaction in agricultural areas inhibits plant root growth through increased mechanical resistance, altered water and nutrient supply. The main objective of this study was to evaluate spatial distribution of roots and its effect on water uptake of maize grown on field with subsoil compaction. Two treatments were examined: complex melioration consisting of deep loosening in combination with drainage and control without applied meliorations. Root observations were conducted on vertical and superposed horizontal planes covered with a 2 cm grid short after silking. Root distributions expressed as index of density and/or dry mass density were estimated down to 1 m soil depth and with a distance to a plant base. For analysis of root distribution pattern on the horizontal planes, a Variance to Mean Ratio (VMR) test was applied. Soil water monitoring were conducted during the vegetation period. On the vertical planes, root densities were similar in the topsoil of both treatments, but the results were significantly higher in the subsoil of the meliorated one showing deeper allocation of root density. In contrast, the control had more squares with lots of roots (i.e. higher indexes) just at the top- subsoil boundary owing to bunching of roots in macropores. The horizontal planes in the control generally consisted larger areas without visible roots and thus great distances for water and nutrient transmission, especially in the subsoil. The estimated VMR also pointed toward different levels of root clustering. Consequently, an inhibited water extraction from the subsoil in the control, a delay in crop ontogenesis and a less biomass production was established during the observed period.