Reducing nitrogen losses from farms

Oct 2016 – Sep 2021

A research programme with funding from the Ministry of Business, Innovation & Employment (MBIE) Endeavour fund

The agricultural sector, particularly dairy farming, is facing increasing demands to reduce its greenhouse gas emissions and nitrogen leaching. Animal emissions of methane from grazed systems are a major contributor to agricultural greenhouse gas emissions, but emissions of carbon dioxide and nitrous oxide from soils are also important. Increasing stocks of soil organic carbon can contribute towards a solution to mitigate both greenhouse gas emissions and nitrogen leaching by removing carbon dioxide from the atmosphere and capturing it in soil. Increasing soil organic carbon stocks improves soil quality, water and nutrient holding capacity and productivity. Farm management practices to promote climate-smart agriculture can contribute to increasing food security and mitigating climate change, with both of these aims consistent with the Sustainable Development Goals of the United Nations.

Satellite image of the South Island of New Zealand showing the location of the research site. The image highlights the extensive conversion of dryland farming to intensive irrigated dairy farming on the Canterbury Plains east of the Southern Alps. This illustrates the concept of Ki Uta Ki Tai, (from the mountains to the sea) and the potential flow-on effects of our farming decisions on the consequences of water quality for Te Waihora. (Google Earth)

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.

Overview

Research outputs

pdf Outputs from the reducing nitrogen losses from farms programme pdf File, 743 KB

Goals

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.

Collecting samples of lucerne foliage to measure biomass and for chemical analysis (Bradley White)

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.