Science puts couple on the front foot
4 May 2018
Facing the challenge of reducing nitrate leaching while remaining profitable has spurred Canterbury farmers Grant and Jan Early to take part in the DairyNZ-led Forages for Reduced Nitrate Leaching research programme.
Grant and Jan farm near Mayfield in Mid Canterbury, an area deemed a ‘red zone’ by Environment Canterbury. The couple are required to reduce their nitrogen (N) loss by 15 per cent by 2025 and 36 per cent by 2035.
“That’s not going to be easy,” says Jan. “With the tools we have at the moment, it’s going to be very difficult, if not impossible. That’s why we wanted to be part of a research project looking at what you can do on-farm in a practical sense, and that’s going to mean we can reach that target.”
Foraging for solutions
Led by DairyNZ, Forages for Reduced Nitrate Leaching (FRNL) has focused on finding plants that better utilise N within the soil and reduce N when passing through the cow – all while maintaining or improving profitability.
The six-year programme combines the expertise and resources of DairyNZ, AgResearch, Plant and Food Research, Lincoln University, Foundation for Arable Research and Landcare Research. The main funder is the Ministry of Business, Innovation and Employment.
A network of monitor farms has been established in Canterbury, including dairy, arable, sheep and beef and mixed arable and dairy properties, as a way to implement some of the promising science and research on a commercial scale.
For Jan and Grant that’s meant trying a range of options, including adding plantain to their pasture mixes; growing fodder beet on the platform followed by a catch crop of oats; and reducing their stocking rate.
“Part of FRNL has involved modelling to look at various mitigation options to evaluate the impact on the environment and profitability,” says Grant. “While never an absolute science, it does give us confidence to implement some of those options which we feel will work within our system.”
Perks of plantain
Science shows that cows eating plantain excrete urine with a lower N concentration than when they’re eating the regular perennial ryegrass/white clover pastures. Also, plantain better captures nitrogen in the soil. Trial work suggests it needs to be at least 25 per cent of a cow’s diet to be of significant benefit.
“Establishing plantain within a pasture renewal programme is relatively straightforward. The trick is how to economically achieve this on a larger commercial scale,” says Grant.
“Last autumn we trialled broadcasting a high rate of plantain seed (8kg/ha) with fertiliser after cow grazing. The trial paddocks were grazed again at 21 days and 29 days post-spreading, half of which were pre-mowed and half grazed normally.”
Grant says the seedlings are clearly visible and the next growing season will show how well the plantain establishes. Other monitor dairy farms in the FRNL programme are trialling direct drilling into existing swards and Lincoln University is carrying out similar trials on a small plot basis.
Contract milker Will Burrett is learning to manage plantain, including how to accurately measure its dry matter.
“Plantain measures differently to grass on the rising plate meter, especially with greater than 30 per cent sward composition,” says Will.
“There is an equation to recalibrate the plate meter, but for simplicity, I take off 150kgDM/ha from the plate meter reading. It seems the grazing habits of the cows have an influence on the persistence of the plantain over time, with animals grazing the plantain consistently at 1400kg DM/ha.”
Early start on fodder beet
Feeding fodder beet is another way to reduce N leaching. It’s high in carbohydrates but low in protein. As well as feeding it on their support block during winter, the Earlys grew it on the milking platform as an autumn feed this year.
“Fodder beet on the platform enables you to grow a similar amount of dry matter as you would from pasture and it has the advantage of partly transitioning cows before going on to fodder beet for winter,” says Will. “When they leave the farm they’re up to 6kg of fodder beet/cow/day, enabling weight gain in early June.”
Science suggests the benefits of fodder beet in reducing nitrogen leaching outweighs the higher stocking density.
Catch crops and cows numbers
This year the Earlys planted a catch crop of green feed oats after the platform of fodder beet in a bid to use nitrogen in the soil rather than allowing it to leach out in winter and early spring rain events.
“If you just left it fallow for the winter then it’s a prime target for leaching,” Jan says.
The Earlys have also reduced cow numbers from 1470 three years ago to 1400 now, looking for efficiencies to improve profitability while reducing nitrogen losses.
“If you can get a better understanding through the FRNL programme that a different crop or pasture species, a different fertiliser strategy or improved animal genetics will convert dry matter into milk more efficiently with less environmental impact, this will be of benefit to the industry’s longevity,” says Will.
Grant says the trial work hasn’t involved any radical changes to farm management, apart from a greater requirement for Will to collect daily data. This includes irrigation, supplements fed, effluent spread, cows’ daily movements, fertiliser applied, silage made, pasture renewal, production, rainfall and the composition of milk.
“Understanding all the little bits that go into every single day’s management decisions creates a clearer picture in order for us to improve our performance economically and environmentally,” Grant says.
Will says he doesn’t find the extra work collecting data onerous.
“That’s where high-performance farming is already and that’s what consumers are going to demand anyway. They’re going to want to know exactly what went into that litre of milk.”
Additional information includes soils tests and monthly tests of pasture swards and supplements, along with independent body condition scoring of cows at dry off and when returning to platform from the wintering block.
Will and the Earlys work closely with DairyNZ scientist Paul Edwards who makes monthly visits to the farm to ensure data quality, capture management decisions and provide support.
“Paul’s put a lot of time into designing the data-input spreadsheet. It’s an Excel, form-based system with a lot of moving parts, designed to capture common information across multiple farms,” says Will.
Four years into the programme, the farm has made an improvement to its N-loss figure (see table in gallery) and Jan says some of the lessons being learned are being picked up by other farmers.
“Low payouts have forced farmers to look at their stocking rates and supplements fed and by default some of these system changes have been beneficial to overall N loss,” she says.
“Nutrient losses are a real issue in this area so being involved in the FRNL programme is a way of front footing it and hopefully helping in a small way to address it.”
To learn more about FRNL and see reports from the monitor farms involved, go to dairynz.co.nz/frnl.
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