Patient converters set for low N future

category Environment

The Jarmans have been adaptable farmers for more than 150 years – and they’re still innovating.

Paul and Ann Jarman run Essendon, a 400ha dairy farm at Greendale, central Canterbury.

Supplying Westland Milk Products, Essendon is milking 860 cross-bred cows and includes a fully self-contained block for wintering and growing out young stock. About two thirds of the 400ha is milking platform.

The Jarmans are connected to Stage 2 of the Central Plains Water (CPW), a high-pressure, piped irrigation scheme covering much of central Canterbury.

Sustainability and minimising the environmental footprint of the farm is the key driver to decision making regarding farm management practices. Essendon is monitoring some paddocks weekly to get an accurate fix on moisture and irrigation requirements to minimise nitrate losses.

Working with their contract milker, Paul and Ann are also using CRV Ambreed genetics to help reduce the farm’s nitrogen footprint.

The company has research indicating that LowN Sires genetics could cut a farmer’s nitrate losses by 20% over several generations of breeding. CRV Ambreed’s Low N Sires programme is based on breeding dairy cows with lower levels of milk urea, which is expected to reduce urinary nitrogen.

Paul said he was prepared to invest in the genetics, knowing the importance of reducing their N footprint under planning regulations.

He likened opting for LowN Sires to Merino breeding, the career he pursued passionately before starting a dairy conversion in 2013. “You get a good fine flock by measuring, testing and weighing. The same is true for your approach to the dairy industry; you’ve got to have good, objective, performance-based selection of sires. And that’s where the whole AI in New Zealand comes from.”

Paul and Ann started using bulls from the LowN Sires programme only two years ago, soon after CRV Ambreed launched it. The first yearling calves from LowN Sires will be on the ground for mating this year and they’re confident it will help them to hit their targets for N-reduction.

“It’s part of a long-time project to achieve what we want to achieve over what’s probably a 20-year period. In the fullness of time, it could be quite helpful,” Paul said.

CRV Ambreed head geneticist Phil Beatson said a dairy cow ate about 180kg of nitrogen a year as plant protein. About 30kg ended up as milk and a little bit to body maintenance and growth. Of the remainder, about 75-80kg was excreted as urinary nitrogen and the rest was excreted as faeces.

On average around 20% (16kg) of this urinary nitrogen ended up being leached into groundwater.

Importantly, a small amount of the nitrogen in urine is converted to nitrous oxide – a long-lasting greenhouse gas. Reducing urinary nitrogen was critical to reducing both leaching and greenhouse gas emissions Beatson said.

As CPW shareholders, Essendon operates under a company-audited farm management plan. The owners and their manager were pleased to receive an ‘A’ grade first up, with no recommendations.

“Now, with pivot technology on most of the farm, we can apply these small amounts little and often. As long as you haven’t got water leaching through the soil profile, there’s a very good chance you haven’t got any nitrogen leaching through,” Paul said.

With irrigation plans under control, the remaining risk for nitrate leaching is in winter, when there’s higher rainfall.

The farm had also been using plantain in their pasture and had a “little and often” approach to fertiliser use, based on results from the Lincoln University dairy farm.

Paul said, as a couple, they backed CPW from the start, even though they had a long wait for the scheme to start: “We signed up to it in our late 40s and ended up seeing completion of it in our late 60s.”

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