Water fight: Farmers strive to limit cows' environmental footprint

Photo: RNZ / Nate McKinnon

As nitrates creep up in some Canterbury drinking water supplies, dairy farmers are striving to limit nitrate leaching and their cows' environmental footprint by planting special crops and experimenting with new winter grazing systems. In the second of [ https://www.rnz.co.nz/news/national/581910/what-s-really-going-on-with-canterbury-s-water RNZ's three-part series Water Fight], Anna Sargent reports on efforts to remedy the region's water quality woes.

A gentle breeze rolls through an oat crop on Andrew Barlass' dairy farm in the foothills of Canterbury's Mt Hutt, turning the field into a shimmering ripple of green.

The long pale stems are ready for harvest but the oats have already done an important job soaking up some of the nitrogen left behind from winter grazing.

Set against a picturesque backdrop of snow-capped mountain peaks, Barlass's 900-hectare farm is home to about 1500 dairy cows.

The third-generation farmer is trying to prevent nitrate leaching and nutrient run-off with his catch crop of oats, as levels of contaminants inch up in some rural Canterbury drinking water supplies.

"I've always been interested in nature and the environment. As farmers we're out here, we're touching the soil everyday, it's the sort of the values that we have as a family that I want my children to be able to enjoy," he said.

"The catch crop is designed to soak up the nitrogen, the oats grow in cooler temperatures than grass so we can get these in August, they take up the residual nitrogen that's left in the soil and then we take that for silage later on."

Photo: RNZ / Nate McKinnon

A 2022 Plant & Food Research project involving Otago and mid-Canterbury farm trials found catch crops reduced soil nitrogen leaching by up to 60 percent and cut sediment run-off by about 40 percent.

Barlass was also trialling hybrid bale grazing to improve soil health and prevent cows sitting in mud that could end up in