Abstract

Nitrate attenuation factors are becoming an important and routine consideration in applied water resource management within New Zealand, as nitrogen load limits are being set for hydrological catchments. The few nitrate attenuation factors so far reported in the New Zealand scientific literature have been calculated from comparing landscape nitrogen yield with catchment nitrogen yield. An important limitation of the nutrient budgeting approaches so far employed is that they do not consider the fate and transport of nitrate in the vadose zone-groundwater continuum that links the base of the soil zone with surface waters. There have been few objective scientific studies targeting measurement of nitrate reactivity below the root zone in New Zealand. The few in situ measurements that have been made have mainly been focussed in the Waikato and Manawatu-Wanganui regions. Owing to the paucity of available data on nitrate reactivity below the root zone, much discussion pertaining to nitrate attenuation in New Zealand groundwater remains speculative.

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