Environmental, Terry Kilday (Canterbury)


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Key findings

Willsden, part of the Camden Group, is a dairy farm using cross-bred cows and produces about 1550kg MS/ha. This page looks into the farm's efforts to manage nitrogen (N) leaching and emissions. They tried three scenarios, including soil moisture monitoring, early culling, and adjusting their effluent area. The results show that with careful management, they can reduce N leaching and emissions while maintaining profitability. Efficient irrigation and optimising fertiliser use are crucial. The farm manager, Terry Kilday, stresses the benefits of understanding N leaching and how managing it can support a profitable business while considering future environmental challenges.

Willsden is one of four dairy farms in the Camden Group plus support blocks. Willsden runs cross-bred cows with a stocking rate of 3.5 cows/ha, producing around 1550kg MS/ha.

The farm is set up as a system 3 farm however, at times of poor growth more supplement may be used. The soils are Lismore stony silt loams which are free draining and irrigation water is supplied from Central Plains Water.  There are two centre pivots irrigating 52% of the farm with the balance being 44% Rotorainers and 4% K-line.

Three scenarios were explored for Willsden.

  1. Scenario 1 looked at implementing soil moisture monitoring for irrigation. This reduces the annual water applied per hectare from 640mm to 480mm on the Rotorainers and K-line, and from 465mm to 390mm on the pivot irrigators. This decreased N loss and emissions, and profitability remained unchanged.

  2. Scenario 2 looked at also removing April nitrogen applications, culling early to match feed demand to supply, and implementing soil moisture monitoring. This further decreased N loss and emissions, and reduced profitability.

  3. Scenario 3 looked at increasing Willsden’s effluent area from 68ha to 80ha and reducing the N fertiliser application on this area. This is based on the current system with no change to irrigation or animals.

Key findings

  • Willsden is largely a grass-based system and have shown that they can reduce their N fertiliser use and get some reduction in N leaching. To reduce N leaching significantly, irrigation scheduling and very efficient Rotorainer management will be required.

  • Some reduction of nitrous oxide can be achieved by reducing the farm’s N surplus though the use of less N fertiliser for the same milk production.

  • Focusing on efficient irrigation can reduce environmental losses for irrigated farms. However, to do this, replacing infrastructure may be required and this could increase total pasture grown and therefore emissions.

“Camden group have been involved in this project as we have experienced the benefits of being involved in community projects through our involvement in the Lincoln University Demonstration Farm (LUDF) and how they help pave the way for other farmers. Benefits to the Camden Group of being involved are having a better understanding of the drivers of N leaching and what is required to mitigate it. It has also given us the confidence to know that we can make changes and still have a highly profitable business. We know greenhouse gas emissions are on the horizon and we are learning how one affects the other.”
Terry Kilday – farm manager.

Changes 2018/2019 and Scenario 3 Scenario 1 Scenario 2
N-leaching change from 2013 baseline -17% -41% -44%
GHG losses change from 2013 baseline -3.6% -4.5% -6.4%
Profitability change from 2018/2019 season 0% -2%
Last updated: Aug 2023
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