Marvelous legumes, the powerhouse plants for pastoral production

Written by Pat Deavoll

Legumes have come under the spotlight in recent years as farmers look to these powerhouse plants to drive production, particularly in dryland and hill country environments.

Legumes have nodules on the roots that contain nitrogen-fixing bacteria. They are able to fix high rates of nitrogen and use water efficiently, and are becoming increasingly important as the environmentally sound way of introducing nitrogen to pastures.

A number of research trials have focused on the management of legumes to maximise productivity and profitability in different environments. These include two Beef and Lamb New Zealand  [B+LNZ] Innovation Farm projects.

Hamish and Annabel Craw of Banks Peninsula have been running a B+LNZ Innovation Farm project for four years trialling the application of sprays to increase the legume content of the grassy surface of their paddocks.

The couple farmed 420 hectares at Little Akaloa on the northern side of the peninsula. The property had sweeping views of Pegasus Bay, with the seaward Kaikoura Ranges in the distance. 

They are holding a legume-focused field day on their farm on November 13.

The Craw's aim was to find the optimal spray-out method and legume pasture mix to improve the quality and quantity of their hill country pastures.

"For a while, we had been looking at ways to improve the quality of our pasture in our higher un-cultivatable country," Annabel Craw said.

"We weren't happy with the level of sub-clover we had so wanted to figure out how to improve the quality and quantity.

"Hamish has always thought there was a way of allowing existing sub-clovers [which are legumes] to flourish. We didn't want to do a 'spray and pray' where you spray the whole hillside and hope something comes back. We are too summer-dry to have any certainty with that."

"The idea was to find a technique to promote existing sub-clovers rather than killing everything off and starting again."

The couple put a proposal to B+LNZ to become an innovation farm based on trialling the promotion of their existing clovers. B+LNZ decided the proposal aligned with what it wanted from an innovation farm and the proposal was accepted.

The pair put together an annual plan based on what they wanted to achieve.

The first year was about trialling the different options and having the confidence to replicate these in a paddock in year two. 

They trialled two paddocks. The first was "a bit challenged" because of a dry summer in 2015. But it did allow the sub-clover to dominate the pasture and reduced the amount of poorer grasses, improving the quality.

The process was replicated in larger paddocks for another three years.

The Craws admitted that in a dry year when feed was short, spraying out their pasture was a difficult decision.

But the chemical regime they used showed promise and allowed existing sub-clover to flourish in their uncultivated land.

As the project evolved, the Craws realised that having a low stocking rate to control pasture mass had been positive. Pasture allowed to go to seed built up mass and seeds couldn't get into the soil to germinate and establish.

Annabel Craw said four years on the project had evolved from the initial focus on what spray treatments to use, to how to manage grazing so that remaining sub-clovers were allowed to multiply seed, germinate and establish.

"I think this kind of development is very relevant to the way sheep and cattle are being pushed back into the hills. Our whole driver is around lambing per cent and weaning drafts and weight" she said.

" We need to be able to have our whole farm ticking so we can maximise our production, which we are trying to get happening before it gets summer dry. 

"By January, early February we want to be down to our capital stock so we can rest the farm and set it up for the autumn. Not try and push things through when its dry and go backwards.

"It has definitely been a success. As farmers, B+LNZ  had given us the confidence to try something new."

Annabel Craw said the field day marks the conclusion of their Innovation Farm programme and would be an ideal opportunity for farmers to see what worked for them but also hear how other farmers in other environments were managing legumes.

For information on the field day go to the B+LNZ website.