Composting barns: Farmers have many research questions, DairyNZ scientist says

Dairy NZ senior scientist Dawn Dalley spoke about researching materials to maximise the amount of times cows lie down in open loafing areas in wintering sheds at an event in Eastern Southland last week. Photo / Shawn McAvinue

Research on composting barns was limited but there was no shortage of questions, a scientist says.

Dairy NZ senior scientist Dawn Dalley said DairyNZ was hoping to launch a project researching cows in composting barns to better understand any issues facing farmers.

“We have heard some work well and some don’t work quite so well.”

Information from international studies on composting barns was being collected.

The research questions on composting barns included the impact of the stocking density in the barns.

Another question was what frequency and depth of tilling of material in the barns was required for composting to occur.

The size of the surface area of the material in the barns would dictate the amount of time it would take to compost, she said.

Harder wood could take longer to compost, he said.

Farmers wanted to know if a test was available to show if the material in the barns had stopped composting and to have a way of getting it going again, she said.

“There is no shortage of research questions.”

If more farmers built composting barns it could increase demand for sawdust as bedding material.

Four lying surfaces were being researched to reveal which one cows laid for longer on.

Post peelings were considered the “gold standard” of materials for cow lying times, he said.

The other three alternative materials researched were a recycled plastic and rubber resin mix, a shredded rubber and resin mix and a hard rubber matting.

Cows wearing devices to measure lying time were put on the four materials.

The cows lay on the post peelings for about 11 hours a day.

On the hard rubber, cows lay for the least amount of time, about eight hours a day, Dalley said.