Nitrogen

A major research effort aimed at cutting nitrogen (N) losses without losing sight of farm viability is putting practical system change under the microscope.

In this episode, Anne Lee speaks with Dr Racheal Bryant, Associate Professor at Lincoln University, about the Low-N Farmlet Trial that’s found stacking a number of N mitigations together on-farm can cut N losses by up to 50%. The multi-year study is part of the DairyNZ-led Low-N Systems research programme with studies involving the Bioeconomy Sciences Institute (formerly AgResearch), Fonterra, AbacusBio and CRV with funding also coming from the Ministry for Business Innovation and Employment (MBIE). Dr Bryant explains how modelling and onfarm measurement have been used to test combinations of lower nitrogen fertiliser rates, diverse pastures, genetics and all-grass wintering systems, revealing where significant reductions in nitrate leaching are achievable, the trade-offs with profitability (a 7% reduction in some cases), and how farmers can assess which mitigations may work best in their own systems.

In this episode, DairyNZ scientist Dr Kirsty Verhoek explains how heat stress affects cow comfort and productivity, and how the Grazing Heat Load Index (GHLI) improves on traditional measures like the Temperature Humidity Index. Dr Paul Edwards discusses how GHLI, combined with digital technologies, helps farmers identify regional heat stress risks and take timely action. Dr Roshean Woods introduces a new bulk milk urea (BMU) tool that provides near real-time insights into dietary nitrogen surplus, helping farmers optimise herd health and reduce nitrogen loss. Together, they highlight how these tools support farm resilience and sustainability in a changing climate.

This week we caught up with some farmers who shared their expertise at SIDE’s 2024 Conference, along with a geneticist. From new traits being researched for the fertility breeding value, to tackling strategies to reduce N loss, and finally how to navigate the ins and outs of share milking contracts, hosts Sheryl and Anne cover it all.

An effluent system upgrade at the Lincoln University Dairy Farm (LUDF) is helping to make more effective use of the $13,000- $14,000 worth of nutrients cows deposit on the yard and farm dairy each year.
Words Anne Lee

The sky won’t fall if the dairy industry reduces its inputs and changes management practices to meet looming environmental regulations, nor will that spell the end of the New Zealand dairy industry. That’s the view of a former DairyNZ scientist. Words Elaine Fisher

Fertigation - applying fertiliser through irrigation - has allowed Pamu Farms to make significant cuts to nitrogen use on a Canterbury farm. Anne Lee reports.