AGGREGATION OF A DEGRADED LOWLAND SOIL DURING RESTORATION WITH DIFFERENT CROPPING AND DRAINAGE REGIMES

Rate of change of surface soil aggregation under different cropping an d subsurface drainage regimes was studied on a badly degraded lowland soil in the Lower Fraser Valley, British Columbia, Canada, The soil wa s the silty clay loam Humic Luvic Gleysol. Two cropping practices - co ntinued spring-sown barley underseeded with clover for winter cover cr opping and a 3 year grass ley - were established in a subsurface drain ed site and a poorly drained (no subsurface drainage) site. Grass ley consistently improved surface aggregate stability of drained and undra ined soils when compared to cash-winter cover cropping integration. Im proved aggregate stability with grass was significantly correlated wit h increasing soil organic carbon content. Aggregate stability and its correlation with organic carbon varied with time of sampling, being lo wer in the early spring and higher in the fall, Seasonal variation in aggregate stability was attributed to soil water content at sampling.