Developing decision support tools for restricted grazing managements to mitigate environmental impacts

Changes in grazing management of dairy cows have the potential to reduce the environmental impacts of grazing pasture when soils are wet. These impacts include soil pugging damage, nitrate leaching and nitrous oxide emissions. A project funded by the New Zealand Government in support of the Livestock Research Group of the Global Research Alliance investigated the development of a soil moisture-based decision tool to assist with applying restricted grazing strategies to reduce nitrous oxide emissions. Industry workshops tested the assumptions of the decision support framework and potential implementation strategies. The potential cost benefit of feed changes related to restricted grazing strategies were compared with the three classes of environmental impact; pasture production loss from soil pugging, nitrate leaching potential and nitrous oxide emissions. Restricted grazing needed to be applied at different times to achieve mitigation of each of these environmental impacts. The results of these strategies were presented at two workshops and used to explore the utility of the decision making process when implementing restricted grazing managements in regions prone to waterlogged soils and treading damage. The level of topic familiarity was critical to the outcomes of the workshops. The North Island group had little experience with the concept and stated that they learned how much more complex the practice of restricted grazing was, compared to their previous thinking. The South Island group were all practicing forms of restricted grazing and so had developed practices that suited their farms, based on their current knowledge and observation. A key difference between the groups then was that one group had mainly theoretical knowledge, while the other group also had practical knowledge of the approach. This led to different issues being important to the two different groups. While one group wanted full cost-benefit analyses and detailed grazing plans, the other group understood these aspects and required more detail about how a mitigation tool would be implemented. Each group focused on different environmental impacts that were regionally important. These findings confirm that previous experience must be accounted for in the interpretation and development of implementation pathways of a new technology. Investigation into the development of this tool is on-going.