Key legume findings focus of field day

FIRST YEAR: Agriculture scientist Dr Paul Muir (centre) spelt out the lessons learned from year one of the innovation farm hill country legume project at a field day on Wairakaia Station at Muriwai on Monday. Picture supplied

EFFECTIVE oversowing was difficult and everything had to be right to be successful with grass suppression always necessary to establish legumes in hill country — those were key findings in the first year of a legume-focused trial on Wairakaia Station at Muriwai.

Agriculture scientist Dr Paul Muir presented his first year trial summary of the Beef and Lamb NZ (B+LNZ) innovation farm project at Rob and Sandra Faulkner’s property on Monday. The Faulkners are one of three B+LNZ innovation farmers on the East Coast.

Around 50 farmers attended the field day. The project focuses on improving the legume content on uncultivatable dry land hill country.

“What have we learned to-date?” Dr Muir asked. “Oversowing is difficult and everything must be right — timing of spray out/suppression, insecticide treatment prior to sowing, viability of seed, slug bait at sowing.

“One of the new species we are looking at is arrowleaf. It is an annual that produces a large bulk of feed, but it is not without its challenges. It does not like cold or wet conditions and it is best suited to north-facing hillsides. Winter growth was poor at Wairakaia here in 2016, but has been good on a north facing site in CHB in 2017.

“Arrowleaf is a prolific seeder. A single kilogram of arrowleaf seed has 800,000 seeds, so there is up to 10 times as much seed per kg as some sub-clovers. However, because it flowers at the end of its stems getting seed-set under grazing is hard.”

Dr Muir said achieving good seed production in 2016 resulted in a significant amount of trash to clean up in 2017 as the paddock was left ungrazed through most of spring to achieve the best possible seed-set.

“This proved difficult to clean up even for a mob of cows and meant that it was difficult getting seed-soil contact for the new crop of annuals and plantain sown in autumn 2017. The trash also seemed to be a great reservoir of slugs. Slug bait was re-applied on July 24 but in hindsight this may have been too late.”

What still needs to be learned?

“Grass suppression is always going to be necessary to establish legumes in hill country. However legumes are slow to establish and grow through the winter so that by the time they get moving, the grass has recovered from its suppression and is providing active competition.

“Should we be looking at a mid-winter spray and oversowing programme to ensure good soil moisture and good seed/soil contact — and what impact does this have on seed-set? How do we manage the grazing of arrowleaf in the establishment year to maximise seed-set but minimise trash after seeding?

“What do we sow in year two while we are waiting for the hard seed-set by the arrowleaf in year one to germinate? Our current thoughts are that we may resow arrowleaf specifically as a grazing proposition in year two, whereas in year one the aim was to set seed for future years."

On the Pukehou Hill (13ha) a second component of the project is looking at introducing annual legumes after forestry.

“This objective aims to get better performance of land during the early years of a forestry replant,” Dr Muir said. “Rather than simply replanting in pines and accepting a bit of grazing from regenerating native grasses, Rob Faulkner is keen to have high quality grazing among the pine trees.

“A burn-off provides the opportunity to start with a relatively clean slate and sow clovers which will provide a seed bank for subsequent years. The theory being that light stocking rates will allow lamb finishing through spring without impacting on the young pines.”

Dr Muir said the overall aim of the innovation farm programme was to get more legume on dry land hill country so that lamb weaning weights increase.

“Much of what we do is pushing the boundaries to see what is possible on a relatively small area. We are at the beginning of the Innovation Farm programme and at this stage we are not making any recommendations.”