In the last 20 years, there has been major conversion of dryland farming to irrigated dairy farming with the increase in irrigation. This has occurred especially in eastern areas of the South Island where soils are shallow and stony. This has increased national greenhouse gas emissions and has also contributed to concerns of increased nitrate leaching on freely-draining soils. Soil carbon can also be lost through reduced inputs from plants and decomposition of soil organic matter. Removal of plant biomass by cutting and grazing and returns of carbon from dung deposition are important components of the carbon cycle. Increasing soil carbon stocks and more efficient use of nitrogen can mitigate climate change, improve water quality and lead to systems that are more resilient.
This MBIE-funded research programme seeks to investigate and recommend practical changes to farm management practices to reduce soil carbon and nitrogen losses from dairy farms on stony soils. The Programme is a collaboration between Manaaki Whenua – Landcare Research, Lincoln University, Plant and Food Research, Scion, University of Canterbury and the New Zealand Agricultural Greenhouse Gas Research Centre. Using Lincoln University’s Ashley Dene Research & Development Station to conduct experiments and make field measurements, we are investigating linkages between the plant and soil processes that regulate carbon and nitrogen cycling. Our aim is to provide management options to manipulate carbon inputs using different grassland and fodder species and irrigation to reduce carbon and nitrogen losses.
Our direct measurements and scenario testing using models will enable us to provide evidence-based recommendations to rural professionals and farmers to reduce nitrogen losses from farms. This five-year programme will end in September 2021.