Hay bale grazing: Wintering with less mud
More Waitaha Canterbury farmers have been experimenting with hay bale grazing this past winter in a bid to minimise pugging and retain soil nutrients and structure.
The practice has been endorsed by Bioeconomy Science Institute (formerly AgResearch) soil scientist, Ross Monaghan, who led the Soil Armour study finding cows wintering on hay bales and pasture caused less soil damage compared to stock grazing on crops.
“There’s been a growing interest in alternatives to crop and exploration into pasture-based wintering approaches. This is a continuation of farmers trying to get away from mud,” Ross said.
How hay bale grazing works
Hay bale grazing is a regenerative agriculture practice coined from the coldest climates in North America. Where practical, the method offers an alternative to traditional winter grazing in New Zealand.
The hay bale grazing process
Paddock preparation: Beginning early autumn, paddocks are put aside to allow pasture to grow to pre-grazing cover (around 3000-4000 kilograms of drymatter per hectare) by winter.
Spreading hay bales: Shortly before winter begins, hay bales are spread across the paddock in a checkerboard formation and cows feed on hay and pasture, typically moved every three days.
Soil and nutrient benefits: Litter left behind from the hay bales and established pasture helps protect the soil from pugging and decreases leaching by providing a filter for dung and urine. The hay litter provides seeds that germinate which increases nutrients in the soil.
Improved soil health and pasture growth: This method improves soil health, water infiltration, and pasture growth.
Bioeconomy Science Institute soil scientist Dr Ross Monaghan
Considerations for farmers
The system requires more area per cow than cropping to further help reduce pugging. The benefits to well-drained soils will be higher than wet/clay soils.
To increase the metabolisable energy of the feed, some Canterbury farmers have started to adopt hybrid versions, for example, using a combination of ryegrass and silage.
Hybrid bale grazing offered a solution to those farming in wet climates, where it could be difficult to grow high volumes of hay.
Environmental and animal welfare benefits of hay bale grazing
The Soil Armour research, funded by the Ministry of Primary Industries (MPI)’s Sustainable Land Management and Climate Change Fund, compared two wintering systems on a farm in northern Southland from 2021 to 2023.
The team of AgResearch soil scientists studied whether hay bale grazing reduced nitrate leaching and pugging (mud) in comparison to a conventional crop (kale) wintering system.
Reduced nitrogen impact
Less urinary nitrogen was excreted by cows that were fed a high proportion of hay, and the nitrogen that was deposited was spread around more.
“There weren’t as many patches per hectare as there are in more densely cropped paddocks,” Ross said.
Greater vegetation cover
Measurements also showed vegetation cover was greater in hay bale-grazing paddocks, which was important because it allowed for plants to recover post-winter grazing.
“They have a catch crop effect where they start soaking up nitrogen instead of leaving bare soil.”
Stronger soils and less erosion
The presence of vegetation cover helped to decrease rain-induced erosion.
“Soils with vegetation cover were stronger and didn’t get damaged or disrupted by hoof treading action,” Ross said.
Reduced need for re-seeding
Due to the reduced impact of winter grazing on the soil and pasture, the paddocks used for hay bale grazing often didn’t require annual re-seeding and could be incorporated into the spring grazing systems.
Why well drained soil matters for bale grazing
Pasture wintering was best suited for farms with well-drained and resilient soils.
“If you’ve got wet, poorly drained, or weakly structured soils, cows can still make a hell of a mess, and it looks like a paddock of mud,” Ross said.
Space requirements for winter grazing: The study found that more space was needed for pasture-based wintering. The hay bale grazing that was observed in northern Southland had double the space allowance as the kale system, which is equivalent to 16m² per cow per day versus 8m² per cow per day.
Environmental benefits: Farmers experimenting with hay bale grazing have observed positive environmental impacts, including improved soil fertility and nutrient cycling. Litter left from hay bales contains seeds that germinate, enriching the soil with natural nutrients.
Litter from hay bales provides seeds that germinate which increases nutrients in the soil
Practical advice for farmers
“I think it’s good farmers are toying around with pasture-based wintering systems because producing good quality hay can be tricky to do in the quantities folks want.”
The advice Ross had been getting from practitioners for farmers was that if you’re starting out, try bale-grazing on a small scale or a hybrid approach.
“It is one effective way farmers can replenish the diet a bit if they have particularly poor-quality hay or ME (metabolisable energy) and protein is a bit lower than they’d like,” Ross said.
Further research into pasture-based wintering
Following the Soil Armour research, the Bioeconomy Science Institute has been tracking seven farms across Canterbury, Otago, and Southland that were operating some form of pasture-based wintering.
“We think these farms have all the right characteristics that can deliver and improve environmental outcomes,” Ross said.
Winter 2025 was the first round of tracking, with the initial results due by Christmas. Ross said he hoped the research would continue next year but it would depend on the outcome from this winter.
“It looks encouraging. There’s a WhatsApp group running for the farmers to share their experiences. They seem to be wintering with less mud which is great news.”
Our water and land principal implementation advisor, Shane Gilmer, said farmers exploring alternative wintering options were helping to improve all facets of farm management.
“The part of this research I’m most impressed with is that it reduces nutrient loss to water by improving soil health and structure, and there are also benefits for animal welfare” Shane said.
Learn more: Visit the Bioeconomy Science Institute website for more information on Dr Ross Monaghan's research.