A theoretical study of the environmental and economic sustainability of a dryland dairy system in Canterbury

Abstract

The New Zealand dairy Industry has had rapid expansion over the past 20 years. The intensification of farm systems and change of land use towards dairying is recognised as an important contributor to a range of environmental problems. The build-up of nitrate in ground and surface waters is a headlining issue and has been confronted through government policy. Leaching limits for the Selwyn‐Waihora catchment area requires dairy farms to reduce nitrogen (N) losses by 30% by 2022, with discharge limits of <15kgN.ha⁻¹ by 2035. Meeting these N limits requires the urgent development of sustainable farm systems. In addition to this, over allocation or river and ground sourced water has reduced the options for irrigation in Canterbury to reliance on ‘schemes’ for water supply. The nature of these schemes means water rights are expensive and so with N leaching restrictions the economics and acceptability of conventional systems are becoming suspect. This forms the basis for this project, of exploring the profitability of a dryland dairy system that meets proposed N leaching limits. This study developed a dryland dairy model suitable for the Canterbury region and examined both the environmental and economic feasibility of the model. The proposed model utilises partial housing as the main N leaching mitigation strategy. Lucerne, diverse pastures and fodder beet are also incorporated into the system because of their N mitigation benefits, and suitability to the dryland environment. An autumn based calving has been used rather than the traditional winter/spring calving period. Autumn calving is thought to provide drought management benefits, as well as advantages with winter milk premiums.