Abstract:
Agriculture has widespread impacts on quantity and quality of water resources. The water footprint (WF) is a metric
that quantifies the environmental impacts related to water use. Impacts of rain-fed potato production in the
Manawatu Region of New Zealand were assessed using the hydrological water-balance method of water footprinting.
Hydrological components of this cropping system were quantified using a model validated with field measurements
including the changing soil-water content (green water) and drainage that recharges groundwater (blue water). The
impact of potato cultivation on soil water store was negligible. Potato production was found to be contributed to
recharge ground water at the rate of 72 L/kg of potato harvested. Therefore, this production system has no
deleterious impact on quantity of water resources. However, concentration of nitrate in the drainage was found to be
at the limit for drinking water in New Zealand which is 11.3 mg of N03-N/L. The potential options through fertilizer
management to reduce these impacts were identified. These were found to improve the system reducing the impacts.
Water footprint, therefore, is a useful metric that quantifies the impact of agricultural water use on water resources.
