DIFFERENCES IN SOIL QUALITY BETWEEN AND WITHIN ORGANIC AND INTEGRATED MANAGEMENT KIWIFRUIT ORCHARDS IN NEW ZEALAND

The Agricultural Research Group On Sustainability (ARGOS) is routinely measuring soil quality in New Zealand kiwifruit orchards under different management systems. Established and matched orchards of organic 'Hayward' ("Organic"), integrated management (KiwiGreen) 'Hayward' ("Green") and integrated management 'Hort16A' ("Gold") are being monitored. Baseline monitoring in 2004 indicated significant differences in soil quality between systems but also between within-row and between-row (alleyway) areas. Generally, soil appeared to be of better quality in Organic orchards with lower bulk density, greater porosity and aggregation, more earthworms, a larger microbial population and activity, higher pH and CEC, more potentially mineralisable-N and biomass carbon, and higher levels of some macro-nutrients such as calcium and magnesium. However, Olsen P values were lower for Organic orchards. Compared to within the rows, soil in alleyways was less porous, less aggregated, had lower Olsen P and magnesium levels, but had a larger microbial population and activity, and contained more total and mineraliseable-N and organic carbon. The differences described may not all be caused by orchard management systems alone, and it is not known if they persist. The baseline comparisons suggest that soils under organic management are remarkably different in ways that potentially affect fruit production and quality.