Effects of Subsoiling on a Northern Podzol Soil

Subsoiling is a method of mechanical loosening that can improve water movement through soil. It has been evaluated on a poorly drained northern podzol soil in paddock scale trials over three years. Subsoiling with a tractor drawn implement at 500 mm depth resulted in consistent reductions in surface water contents and lowered water tables. Pasture production was significantly increased in two of the three years and favourable pasture composition changes occurred, Root distribution in winter was also affected, with significant increases in root density between· JOO and 300 mm depth. Recompaction occurred during winter grazing and paddocks required re-subsoiling each year. Despite this lack of persistence, treatments were still considered lo be economic. Gradients of between 5 and 8% are recommended.