Catch cropping

At a time when there's a spotlight on the dairy industry's impact on waterways, Southland dairy farmer Dylan Ditchfield is working on changes that are showing great potential for improvements on-farm and for water quality.

Dylan had Environment Southland land sustainability officer Karl Erikson develop a Focus Activity Farm Plan for his Glenlapa property. In the plan, Karl suggested a sequence crop because of the particularly well-draining soils on Dylan's winter grazing blocks. These soils are a high risk for nitrogen losses to streams and groundwater. "We weren't sure if the climate and weather in the area would make this a viable option, so we were keen to find out," Karl says.

Sequence cropping refers to growing crops on the same field in the same year, one crop being sown after the harvest of the other.

Karl, who has a passion for keeping up with the latest farm systems research, was inspired by a presentation on sequence cropping at a farm field day. It was put forward as an answer to the question: How can nitrogen leaching from winter grazing crop paddocks be reduced?

"Results of that study on a farm in Canterbury show that nitrogen leaching can be reduced by 25–30% by planting a sequential crop of oats immediately after harvesting kale, when compared to traditional kale cropping practices," Karl says.

Typical winter grazing practice on a dairy farm would see cows on paddocks from June until around the end of August. Paddocks are often then left bare until they dry in October/November, when they're re-sown with swedes or returned to pasture.

"The paddocks left for two months have a lot of dung and fertiliser on them, which can be moved easily with some heavy rain and lead to overland flow, causing problems for water quality," he says.

Photo: Dylan's winter grazing paddock before sowing oats and rye grass.

Dylan agreed that sequence cropping could not only reduce his nitrogen losses, but could also help to maintain soil condition and provide an additional feed option for his stock.

In late September, Dylan prepared his paddocks and sowed a cold-germinating crop of oats to cope with the cooler Southland climate. He also went a step further and under planted the oats with an annual rye grass.

"We still want to work with fodder beet in the future," Dylan says. "We recognised the rye grass could give us the flexibility of growing another form of bulk feed (already established post oat harvest) that we could use over the next 12 months before sowing it back into fodder beet the following spring."

Photo: Alice the dog oversees the paddock of cold-germinating oats.

Dylan says the sequence cropping has opened up another alternative to wintering in their farming operation and sees it as a win-win for his farm and the environment.

"We believe it will allow us to feed our younger livestock better, giving us improved live weight gains. It will address the issue of nitrogen losses after winter cropping, because the oat crop takes it up as it establishes and grows. The nitrogen typically would have been lost to the water table."

Dylan says the initial cost to establish the crop is a bit of a disadvantage, and Southland's climate makes it challenging to get the seed sown in early spring. But he's positive about the 7.7 tonne yield from the oats harvest and hopeful they won't need to bring in extra feed for his livestock this winter.

oat harvest.jpg
Photo: The oat harvest.

He cites success as limiting the nitrogen leaching, which he thinks has been achieved, but he says they'll need 12 months to fully understand if they have produced enough high quality, cost effective feed.

"For now we are looking forward to feeding our in-calf heifers on grass and oats, out of the typical muddy environment of winter cropping."

This story was printed in the Envirosouth magazine, which is published three times a year by Environment Southland and delivered to every mailbox in the region. Read it online.

Give our land sustainability team a call on 0800 76 88 45 if you would like to know more.
Page reviewed: 08 Feb 2019 12:45pm