Reducing nitrates for industry good


Grant and Jan Early.
Grant and Jan Early.
Mayfield dairy farmers Grant and Jan Early have been involved in the DairyNZ-led programme, Forages for Reduced Nitrate Leaching (FRNL), which has won an industry award.

The collaborative six-year programme focuses on reducing nitrate leaching on-farm.

It has won a Significant Achievement Award through the Canterbury Section of the New Zealand Institute of Agricultural and Horticultural Science.

The Early’s were among the more than 100 people and ten commercial farms who joined the project to learn more for themselves and as a way to help the industry.

"Nutrient management is going to affect everyone. The sooner we have some tested solutions on how we can mitigate nitrate leaching, while still farming profitably, the better it will be for the industry as a whole," they said.

At the start of the project their farm, which sits on Ruapuna soils and has an annual rainfall of 800mm, was 375 ha, 90 percent irrigated, at a stocking rate of 3.9.

They had a 550 ha dryland support block providing winter grazing (Kale) and grain for the dairy.

Since being involved in the FRNL project the couple have made a few changes to their operation including plantain in their regrassing regime, decreasing their stocking rate to 3.7 cows per hectare, introducing fodder beet on to the milking platform followed by an oat catch crop and reduced the support block to 250ha of irrigated land, using a rotation of fodder beet-barley-short rotation ryegrass-fodder beet.

This has resulted in a decrease in N surplus of six percent and estimated N leaching of 13 percent.

"We now understand the surpluses that come from nitrogen fertiliser and nitrogen in supplements, and how we can change those to make a difference," Mr Early said.

DairyNZ senior scientist Dr Ina Pinxterhuis said those people and business were involved in the science, development and farm application of the FRNL programme identifying pasture and crop options farmers can use to reduce nitrate leaching.

"We’re all extremely pleased to receive this award, and we are even more delighted to see that many farmers have been following the programme and have already adopted some of the lower nitrogen pastures, crops and practices into their farm systems to improve their environmental management."

The programme drew on a cross-organisation team from DairyNZ, the Foundation for Arable Research, Lincoln University, AgResearch, Plant and Food Research, and Manaaki Whenua -Landcare Research. Eight PhD and post-doctoral students have been part of the programme along with several Honours and Masters students.

"We started in 2013 when farmers and the community were looking for better tools and farming practices that could help reduce nitrates in their systems and ultimately reduce any impacts on freshwater and groundwater," Dr Pinxterhuis said.

As part of the programme farmers trialled a range of options to reduce their nitrogen leaching by 20 percent. Options included planting low-protein feed crops such as fodder beet, and pasture species like plantain and Italian ryegrass which result in less or diluted nitrogen excretion by animals and more nitrogen uptake from the soil.

FRNL scientists are now working with Overseer so it can model the practices used as part of the programme.

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