Nutrient Cycling Under Regenerative and Conventional Agriculture Management

The Fertiliser Association of New Zealand places great value on developing New Zealand’s agricultural research capability. One way we do this is through supporting PhD students.

Among the students we are currently supporting is Kaitlin Watson, a Lincoln University student whose PhD looks at phosphorus (P) and nitrogen (N) cycling in dryland pastures under conventional and regenerative agriculture management.

Kaitlin grew up on a dairy farm in South Canterbury, moving to a sheep and beef property in the Mackenzie country, when she was 12.

“Naturally, I took an interest in farming and ended up studying a Bachelor of Agricultural Science (Hons) at Lincoln University. After doing my honours research on falcata lucerne and its potential in acidic high-country soils, my supervisor, Dr Jim Moir mentioned that he was looking for a student to study a soil science PhD looking at regenerative agriculture on the new farmlet trial on Lincoln campus. I decided to take up this opportunity, starting my PhD in July last year,” said Kaitlin.

Kaitlin’s research looks at the yield and botanical composition of regenerative and conventional practicing farmlets, in relation to high and low soil fertility regimes.

“I am measuring P and N cycling under each system as well as soil biology including microbial biomass and soil extracellular enzyme activity,” said Kaitlin.

The individual components of nutrient cycling such as P and N have only rarely been examined and tested in fully controlled grazed environments. Kaitlin’s research aims to close these knowledge gaps by utilising a closed grazed farmlet system, operated under ‘high’ and ‘low’ soil fertility (fertiliser P input) regimes.

Her research will address the impacts of regenerative agriculture principles, such as minimal fertiliser input and diverse pasture species in New Zealand dryland farming.

Kaitlin’s research will play an important role in understanding regenerative agriculture in a New Zealand environment.  With quantifiable data farmers can determine if regenerative agriculture is a feasible practice to implement

“New Zealand is heavily reliant on pastoral systems, and some will argue that best practice conventional agriculture is preferable while others say that we need to promote regenerative agriculture for improved soil health and sustainability. However, there is currently limited evidence out there to suggest that regenerative agriculture can improve our soil conditions,” said Kaitlin.

While there is limited research published on regenerative agriculture, particularly in a New Zealand environment, there is considerable research on individual practices used in regenerative agriculture such as multi-species pastures, minimum tillage and lax grazing. However, these practices have not been investigated together in a farmlet environment.

Of the five blocks established in the trial Kaitlin is studying two which were sown in December 2021.

In the first full season (June 2022 – June 2023), total annual yield was 1.7 t DM/ha lower for regenerative compared to conventional plots. This trend was reflected by growth rates where conventional had a higher mean growth rate of 34 compared to 30 kg DM/ha/day in the regenerative treatment.

“However, we expect treatment differences to change as the trial matures. Next, I will be looking at soil fertility results which will be collected each spring and autumn starting in spring 2023,” said Kaitlin.

We look forward to providing an update on Kaitlin’s research at the conclusion of her PhD.

Kaitlin’s research is funded by the Fertiliser Association of New Zealand. Her supervisors are Prof Jim Moir, Dr Alistair Black, Dr Charlotte Alster and Prof Leo Condron.