Beyond ruminants: discussing opportunities for alternative pasture uses in New Zealand

peer-reviewedThe New Zealand government has set ambitious goals for primary sector growth and of zero net carbon emissions by 2050. This presents an opportunity and obligation to develop new ideas for grassland production systems to increase export value and generate new job opportunities, while reducing environmental impacts. The aim of this paper is to draw on recent research in Europe to investigate some of the alternative and complementary uses for pasture as a feedstock for a green biorefinery. A biorefinery is a facility, or a series of processes, that convert biomass into a spectrum of value-added products. For example, protein can be extracted mechanically from green biomass once harvested. The residual fibre fraction could be used as a low-nitrogen feed for ruminants to reduce urinary nitrogen, while the liquid protein fraction could be processed to make it suitable for mono-gastric or human consumption. Enzymes can promote protein extraction and controlled conversion of insoluble plant fibres and oligosaccharides to foster gut-health promoting prebiotic food ingredients. Anaerobic digestion of residues can then be used to create energy and soilimproving products. Research and demonstration of these approaches in practice, along with the results of feasibility studies, will be required to see which of these opportunities is a good fit for New Zealand pasture systems

An assessment of MitAgator: A farm-scale tool to estimate and manage the loss of contaminants from land to water

Land users and managers require decision support tools (DSTs) that enable them to estimate losses of contaminants from land to freshwater. MitAgator is a DST that estimates losses of nitrogen (N), phosphorus (P), sediment, and fecal indicator bacteria (E. coli) and the cost-effectiveness of different strategies to mitigate losses so that a water quality target can be met at the least cost. Some of the algorithms present within Overseer (a standard DST used in New Zealand for N and P management) have been modified and appended to include spatial analysis in MitAgator. Outputs from MitAgator showed good (R-2 > 0.77; p < 0.001) prediction of measured N and P losses across a range of land uses, but accuracy decreased at larger (catchment) scales. Analysis for P outputs indicated that the most sensitive inputs were hydrological characteristics, followed by soil characteristics and P inputs. Although national databases are used for many of these inputs, if better local data are available, then they should be used. Furthermore, while MitAgator is easy to use by a novice, MitAgator outputs should only be interpreted in collaboration with an experienced user so that limitations concerning cost-effectiveness estimates and spatial and temporal scales are not exceeded