DAIRY NEWS MARCH 13, 2018
24 // MANAGEMENT
Plantain showing its mettle NIGEL MALTHUS
THE PLANTAIN product Ecotain has been shown to reduce nitrate leaching from urine patches in dairy pastures by up to 90%, says Agricom product development specialist Allister Moorhead. Moorhead was reveiwing the product at the recent Lincoln University Dairy Farm Autumn Focus Day; it was held at Lincoln’s nearby Ashley Dene research farm rather than LUDF itself, largely so attendees could inspect an experimental paddock of plantain and white clover. Moorhead said that while plantains had been sold for many years as a means of adding diversity to a pasture, Ecotain was the first farmers could sow specifically for its environmental value. Not all plantains work the same way, he said. The product is an existing cultivar whose properties were only recently identified, via the Forages for Reduced Nitrogen and Greener Pastures projects. Repeated lysimeter work had shown nitrateleaching reductions of up
the ground Changes in the soil brought about by the plant itself reduce the speed at which ammonia in the soil turns to nitrate. However, Moorhead told the focus day that plantain is not a perennial. While it can re-seed itself it cannot set quality seed heads. “It is a plant that sits inside a pasture environment as a secondary or even sometimes a tertiary species, which means the stronger your ryegrass environment the more successful you are as a ryegrass grower; sometimes the harder it will be to keep Ecotain inside your landscape for a long time.” He said there is no easier way to get an elevated plantain content than by sowing it within a new perennial ryegrass pasture, but the plantain content will decline through years two and three. South Island Dairy Development Centre chief executive Ron Pellow said plantain can become a critical part of nitrogenleaching reduction. It would not be a silver bullet “tomorrow” but could become impor■■
Allister Moorhead, Agricom
to 90%, said Moorhead. “The consistency of that research is outstanding when you consider that we didn’t have a clue about this four years ago. “Now when you can get figures of that amount coming out of lysimeters and you’re under pressure to make change on your farm to meet future expectations in nitrogen loss, suddenly getting something that creates that big a difference is a big deal.” Ecotain works in four distinct and independent ways: ■■ Urine is more dilute because of the plant’s high water content ■■ The nitrogen eaten is partitioned differently in the animal’s body so less makes it into the urine ■■ Secondary compounds in the urine act as nitrification inhibitors in
A paddock of plantain and clover on Lincoln University’s Ashley Dean research farm.
tant “the next day,” said Pellow. “We need to start now... thinking about how we’re going to get to where we want to be in five years with it.” Pellow presented graphs showing how a 50% reduction in N-leaching from year one after sowing a paddock in a plantain-mix, could be expected to drop to 15% by year four but could be maintained by re-introducing plantain at regular intervals, say, in years five and eight, by broadcast or direct drilling.
On a farm doing 10% annual regrassing that would eventually get to a 30% reduction on the whole farm. “That needs more work, to see what it will look like on an individual farm and how you’re going in maintaining that plantain percentage,” said Pellow. Moorhead said the biggest issue farmers would face would be weed control because plantain is a broadleaf herb susceptible to herbicides. “It’s always been our problem with the adop-
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Professor Grant Edwards addresses the field day.
PADDOCK CLEAN OF WEEDS
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THE PRESENTATION took place in a recently grazed paddock of plantain and white clover. Moorhead noted that apart from a lone nodding thistle nearby, the paddock was clean of weeds. Lincoln professor Grant Edwards explained that the paddock had been established with Roundup and cultivation, followed by early autumn sowing so the plantain and clover could establish. Weed control since consisted of grazing and mowing. The main weed had been fathen, he said. Edwards presented various research findings on plantain’s performance, saying it provided “substantial” reductions in nitrogen loading. Cows grazing pasture containing more than 50% plantain recorded urine concentrations of about 3g of nitrate/L versus about 5.5g for a control pasture. “This is important because the greater the nitrogen loading of the urine patch, the greater the risk of nitrate leaching particularly in the autumn-derived urine patch,” he said. Lysimeter studies showed that was crucial in reducing the amount of nitrate available for leaching.