Investigation of nutrient management trade-offs using the Land Utilisation Capability Indicator (LUCI). A Canterbury, New Zealand, case study

Abstract

Although agricultural productivity aims to meet global food demand, its expansion and intensification has led to an increase in nutrient load in waterways affecting water quality. This places farmers under pressure in controlling nutrient loss and conserving ecosystem services. The Land Utilisation Capability Indicator (LUCI) model can assist farmers in meeting freshwater policy requirements and identifying where changes on current land management can be done. LUCI is an ecosystem service modelling tool that illustrates the impacts of various ecosystem services. The model was applied in the Selwyn catchment to identify trade-offs between agricultural productivity and water quality. Trade-off results highlighted the possibility of improving water quality at the expense of agricultural productivity. However, to minimise loss of agricultural land or productivity, LUCI identified specific positions within the catchment which require nutrient mitigation. The study also modified the LUCI model. Without any alterations, LUCI uses soil type to determine nutrient loads in a catchment. Modifications done enabled land use to determine nutrient loads. The modifications included adding the Selwyn catchment farm data into the Land Cover Database (LCDB4), assigning export co-efficient (EC) values to different farm types in the study area. LUCI uses the export coefficient approach to calculate nutrient load of an area. Results from the modification process identified dairy farmers as major contributors of nutrient load.