Manipulating carbon inputs to reduce nitrogen losses and retain soil carbon in dryland and irrigated grazed systems.

Background: Conversion of dryland, grazed pasture to high-intensity farm systems with irrigation and the addition of nitrogen fertiliser is a major land-use change in New Zealand. Research is needed urgently to understand the drivers and linkages between soil carbon, water and nitrogen dynamics to determine the impacts of farm management practices on microbiological regulation of soil carbon storage and losses of nitrogen as nitrate in drainage water and as nitrous oxide emissions. The PhD project will add to this understanding by contributing to the activities being undertaken by a large, interdisciplinary research team at the Ashley Dene Research and Development Station, Lincoln, New Zealand with experimental treatments including a range of grazed and forage crops, addition of nitrogen fertiliser and irrigation.

The objectives for the 3-year PhD project will include:
• Quantify the inputs and composition of carbon and nitrogen for different crop types, including components from biomass, root exudates and animal urine
• Determine the microbiological processes regulating rates of immobilisation and denitrification of nitrogen and decomposition of carbon in the soil resulting in losses from gaseous emissions and leaching
• Investigate treatment differences to identify opportunities for improved management practices to increase productivity while minimising carbon and nitrogen losses.

Requirements: Applicants should have a degree and/or an MSc degree in plant-, agricultural- and/or environmental science with experience in microbiology and/or chemistry. Knowledge of water, carbon and nitrogen dynamics in soils and plants and the use of stable isotopes will be advantageous.

Starting date: The project will start as soon as possible and run for three years.

Location: The student will be hosted and receive supervision from within the Lincoln Hub, comprising Lincoln University, research organisations and industry partners.