THE EFFECT OF DIFFERENT POST-RESTORATION CROPPING REGIMES ON SOME PHYSICAL-PROPERTIES OF A RESTORED SOIL

The aggregate stabilities of a soil restored after opencast mining and an undisturbed soil were measured over a complete cropping year from the time of ploughing a grass ley in autumn. This was to examine the effects of various post-restoration cropping regimes on soil aggregate stability and soil porosity. A wet sieving technique and a mild dispersion method were used to determine indices of soil macro- and micro-aggregate stability, respectively. Air filled porosity at field capacity and crumb porosity were also determined. Removal, storage and restoration decreased macro- and micro-aggregate stability. After restoration, the different grass managements i.e. cutting for silage and grazing, had similar effects on soil aggregate stability and maintained greater aggregate stability than the arable regimes. The pattern of fluctuation in soil macro-aggregate stability over the year was similar under all crops at both sites, but at the restored site there was a decline in stability, and differences in the air filled porosity at field capacity developed between cropping regimes. Micro-aggregate stability was less at the restored than at the undisturbed site and showed no seasonal variation or difference between cropping regimes. However, a difference in crumb porosity between cropping regimes did develop.