Dairy Conversion in Practice: Composting Barn Open Day

Dairy Conversion in Practice: Composting Barn Open Day

The Gist: Over 70 farmers and agri pros from across the South Island turned up to the Willesden farms barn open day.

They walked the full 31m × 185m composting barn and saw how it powers a 300ha dairy conversion milking 700 cows. The setup slashes environmental footprint by 46 %, captures all effluent, keeps pasture pug-free in wet winters, and pays back in five years while cows stay dry and productive.

They saw how the barn shelters up to 800 cows in bad weather and winters 550 off-season.

There was a proper Q&A session where Matt Iremonger, Tyler from the Willesden crew, and Professor Keith Woodford answered everything: compost management, day-to-day operations, savings, and the lot in between.

"This dairy shed and barn reduces our N loss water by 65%, our P loss by 35% and our e-coli load in the river by 70%. Carbon footprint, obviously half as much feed, we have the ability to use the compost to put that onto the ground, and obviously there's no effluent that's coming out of the barn, that requires no energy to deal with or no management to deal with. The environmental part of it is really strong."
Matt Iremonger
General Manager for Willesden / Kaimoo farms

The Q&A Uncut: Real Questions, Real Answers

We filmed the whole session. Matt Iremonger and Tyler from the Willesden crew, Professor Keith Woodford and Jacob from Numat Construction answered everything the farmers threw at them.

No script, no dodging, just straight answers from the people who built it, run it and study it.

Grab a coffee, hit play, and hear it from the blokes who live it.

“From a management point of view, it can’t really get much easier.”
Tyler Good
Finishing Manager at Willesden Farms

These were the main topics covered:

Farm background and why they chose dairy conversion

Challenges of running sheep and beef on wet land

Consenting process and the regulatory hoops

Construction delays from weather and how they got through them

Barn design and capacity

How the barn gets used year-round, not just winter

Economics and the target five-year payback (or better)

Straight advice for anyone thinking about starting a composting barn

Changes made during build (solar panels, enclosed southern end)

Positive surprises (public reaction, how calm the cows are)

Calving management inside the barn

How they manage the compost bed day-to-day

Environmental wins (nutrient loss reduction, zero effluent ponds)

Solar panel install and what the ROI looks like

Compost lifespan and why they chose woodchip base

Turning compost into fertiliser (N-P-K values, carbon-nitrogen ratio)

Animal health effects (mastitis risk, body condition scores)

Feeding systems and everyday maintenance

Building materials – laminated timber vs steel, costs and longevity

Ventilation, drainage and the practical bits that make it work

No-Nonsense Feedback from the Day

We had a proper mix of farmers and agri professionals at the Willesden open day. Amongst many others, we had people from Agvance, Forage Farm, MaxCare, Prolam, Perrin Ag Consultants, Ashburton Lyndhurst Irrigation, Fonterra and plenty more.

They walked the barn, asked questions, saw the setup running, and left with real proof in their heads.

Days like this show composting barns are gaining ground. More than 70 turned up because they see the proof: durable infrastructure that works for cows, pasture, and the bottom line.

“All composting systems look simple when they are working well, they can be simple but there’s also mistakes that you can make, we have to make sure that people who go into composting get it right.”
Keith Woodford
Keith Woodford
Professor of Agri-Food Systems

We’ve put the full lot of testimonials in a video below. Watch it and hear it straight from the mob who were there.

“It’s definitely the way of the future I think for dairy.”

“Wintering barns are looking like a really good solution. Really clean, tidy, easy to use and help reduce nitrogen on phosphate paddocks in the winter.”

“This is the only type of facility that I know that can provide profit.”

“They reduced their effluent runoff by 65%. That was a massive benefit. Then the benefit to the animals during wintertime and adverse weather.”

“All composting systems look simple when they’re working well.”

Let’s Price It Right

Get real numbers, not guesses.

We’ll show you the smartest way to build your composting barn: cost-efficient, practical, and built around your farm.

Big Thanks to the Crew & Everyone Who Showed Up

Massive thanks to Matt Iremonger, Tyler Good and the whole Willesden Farms team for opening the gates and laying it all out. You hosted like legends—transparent, straight-up, no holding back on the real numbers, the daily grind and the wins.

Huge respect to Professor Keith Woodford for jumping in, sharing his compost knowledge and answering everything thrown at him.

And to the 70+ farmers and agri pros who made the trip – thank you for bringing the hard questions and the good banter.

Events like this exist to help farmers see what actually works so you can future-proof your business, lift efficiencies and improve returns.

You all made it happen.

Cheers.

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Off-Paddock Systems Comparison Guide

Quickly understand and compare all major off-paddock systems with our comprehensive, one-page guide. It covers:

  • Cost per cow
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Cut through the noise and get the clear insights you need to make an informed choice.

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