Top grower David Birkett is open to trying out new ideas - cover crops, biological products, retaining straw - that will increase his soil's carbon content and limit synthetic fertilisers at his family's Leeston farm, Greenmeadows, in Canterbury. Photo / Tim Cronshaw
Top grower David Birkett is open to trying out new ideas - cover crops, biological products, retaining straw - that will increase his soil's carbon content and limit synthetic fertilisers at his family's Leeston farm, Greenmeadows, in Canterbury. Photo / Tim Cronshaw
Arable Farmer of the Year David Birkett likes to be ahead of the carbon game on his Canterbury farm, writes Otago Daily Times' Tim Cronshaw.
Veering off the beaten path to try out new farming systems and technology comes naturally for Leeston farmer David Birkett.
It helps that serving on many boards allows him to see advances and research before they become mainstream - so he can put his own touch on them to best suit his operation.
The Federated Farmers Arable vice-president runs multi-generation Birkett Farming at Greenmeadows farm with wife, Justine, and parents, Paul and Lois.
The farm's been in the family since his grandfather but goes back to the connected-by-marriage Wills family, who were early pioneers in the province.
A cottage from the 1860s was replaced by an 1881 homestead but sadly had to be taken down after big chimneys were shattered during the Canterbury earthquakes.
A chopping board on the dining table is made with timber from the building as a keepsake of what once stood on the site.
The 200ha farm is on relatively heavy soil types - mostly temuka silt loam with some "loamier and free draining" paparoa soils - which allows them to do things differently than farms on lighter soils.
Birkett said they had developed a farming system that worked on many levels.
"When I say we farm slightly differently, we have a real focus on our soil and keep preserving our soil and maintaining the quality of it.
"A lot of the decisions we make around disease processes or applications - we ask the question: are they the best we can do to help the soil? We've been 25 years incorporating residues and those types of practices," he said.
That sees them working with minimum tillage - only ploughing the soils over when they need to - and direct drilling where they can.
The plough comes out, for example, to remove grass weed problems such as bromes or resistant ryegrass. Burying the grass and leaving it in the soil for the next few years is a good way to kill unwanted seeds and reset the soil.
Then they might put wheat in, working only the very top of the surface to ensure weed seeds do not re-appear.
Beyond that, they prefer a direct drill to sweep over the grazed stalks of previous crops and put in seed without disturbing the soil carbon.
The past few years they have concentrated on putting in cover crops between crop rotations to allow the roots to draw carbon into the soil and bring deeper nitrogen and other nutrients back up into the foliage.
These crops are normally grazed or the foliage returned to the soil, so nutrients remain in the top layer for more shallow-rooted crops.
Cover crops are a key part of regenerative farming.
Birkett does not question its five principles, but he prefers to take a hybrid approach as bare soil at times is a reality of arable farming.
That said, he now finds himself putting in a cover crop during a six-week window in mid-summer, when once a paddock might have been left bare at the height of harvesting.
"Now we probably say: six weeks, get a contractor in to drill it while I'm busy harvesting - quite often you've got feed up to your knees and lambs on, plus it's doing some good for the soil, returning some nutrients so it's a win."
Trading lambs are part of a finely balanced farming system to deliver profitability and environmental payback at David Birkett's Leeston farm, Greenmeadows, in Canterbury. Photo / Tim Cronshaw
Seed producers have fewer choices for cover crops because of future plant contamination, so the Birketts cautiously sow oats, phacelia or buckwheat. Ryegrass, clovers and brassicas aren't used as they are already grown for seed or grazing.
"We are quite limited, but it has been quite a lightbulb moment to see just how healthy the soils are with a cover crop.
One, you can see it visually in the structure - the soil is more porous with more air in it -and the nutrient ratio is better.
"We are doing baselines across our soils for carbon as well so we understand what the carbon level is in paddocks.
"There will be slow gains and we won't see big jumps, but I think when you're in the arable game if you can maintain soil carbons, you are doing pretty well."
The rewards might not come in the way of carbon or greenhouse gas credits, but they do come elsewhere.
Birkett said farmers benefited, with production gains and less need for fertiliser.
They've been involved in a Plant & Food Research project for 23 years. Every seven years, scientists return to the same GPS site in a five-hectare paddock to redo soil tests.
They show that Greenmeadows is gaining carbon, with levels now at 5 per cent - which converts to 8 per cent organic matter. Previously this paddock would have been in the 4 per cent range.
That's higher than average; many cropping farms are on perhaps 3 per cent or 4 per cent, and a lot of cropping soils around the world are probably at 1 per cent.
Other paddocks they have started testing now are at 6-7 per cent.
"One of the big gains is the more organic matter you have, the more nitrogen is released in the soil in a season.
"Obviously, with nitrogen prices going through the roof the last year or so, that's being delivered to me free and the numbers coming out is that about 130kg of nitrogen is being delivered to me every year, and at $3 a kilogram that's around $400 of nitrogen per hectare," he said.
David Birkett was humbled to be named Arable Farmer of the Year. Photo / Tim Cronshaw
In the 1990s they would have applied 250kg of nitrogen on their wheat crops and now it's closer to 130kg-140kg.
Birkett said this research was first done for profitability, to see if they needed to spend so much money on a crop.
"But the outcome has been an environmental gain. We are probably in a really good space in that we learned our profitability lesson, but also had an environmental impact as well.
"Most arable farmers now are well aware of the nitrogen requirements for wheat and ryegrass."
They've nearly halved their nitrogen requirements because they understand the other sources of nitrogen and what's coming out of the soil, he said.
Rotational crops such as white clovers, peas and beans are always followed by a deep-rooted crop such as wheat to pick up the nitrogen from those nitrogen-fixing legumes.
Among other research carried out at Greenmeadows, Environment Canterbury and Plant & Food have dug holes to reveal the root passages of wheat crops.
After a dry summer, the roots had gone through 1500mm-1600mm of clay pan and spread out in the peat bottom.
"Visually seeing that was quite inspiring because it gives confidence that maybe we don't have to irrigate quite as much as we previously thought," he said.
Greenmeadows is fully irrigated with a single lateral irrigator backed up by guns. Pumping costs are low for shallow bores going down to 30-50m.
Heavy soils help to reduce the irrigating window mostly from late October to March. A lot of autumn-sown crops are deep-rooted and, with a one-metre water table, need little irrigation.
Birkett said he was learning all the time and new soil tests for potential mineralisable nitrogen could now tell farmers what was going to be available throughout the season.
That was a huge gain because it indicated possibly another 100kg of nitrogen would become available, he said.
He puts in non-nitrogen strips - two widths of a sprayer - in wheat paddocks every couple of years and every time the yield monitor on the combine harvester has hit the target of the predicted budget.
"That tells me that the 100kg of nitrogen will come through during the season because we've produced the grain at the other end and it hasn't let us down.
"For me, that's a really efficient way of understanding nitrogen. I've got one paddock here that there's enough nitrogen for 15 tonnes so technically I should put nothing in the paddock."
As tempting as it is to do this, he will place a strip in this paddock and limit nitrogen to a buffer of 40 to 60 units as microbes still need the nutrition.
Over the years crop rotations at Greenmeadows have evolved.
In his father's day, the rotation was cereals always following nitrogen-fixing legumes, and that was a self-sustaining system before nitrogen fertilisers gained traction.
When nitrogen fertiliser gained popularity, rotations were adjusted with farmers able to grow almost whatever they wanted - including back-to-back wheat crops.
"I think we are actually going back to the old system now because nitrogen limits are starting to be placed on us and the cost of nitrogen is getting dearer and we are almost going full circle, so I think the old rotation of legumes is a key part of it and will come more into fashion."
Typically, he might have a ryegrass paddock grazed by trading lambs through the winter once the seed is harvested, and this might go into peas in spring.
Leeston grower David Birkett said silos were running low for many grains and seeds, with little free product available for a hungry market. Photo / Tim Cronshaw
The following year, this will be re-planted with wheat to pick up nitrogen the pea crops have delivered into the soil. That minimises any environmental losses.
After that, the paddock might go into white clover for seed, followed by lamb grazing over the summer and once again into wheat and then a vegetable seed crop such as nutrient-neutral radish or brassicas.
Birkett said it's more complicated than this, as farmers today have to look beyond rotations to outside influences.
"We also have to take into account input costs, markets, availability of contracts, shipping - the whole decision around a rotation is quite complex these days.
"You have to know what's happening around the world a little bit and what's happening in the marketplace and what the demand is."
Previously, there have not been enough contracts for, in particular, herbage seed -ryegrass and clover — for farmers to grow them.
This has reversed as Europe struggles with climate problems and companies are offering more growing contracts than farmers can deliver.
He said they had not been in this situation before and with virtually no free land left in Canterbury, some of the crops would have to go to other regions.
That might mean competing against dairying, so the companies would have to pay well, he said.
A wet harvest earlier this year was a tough one for Canterbury farmers. The Birketts were reasonably lucky, managing to get all their autumn-sown ryegrass in before the weather packed in, but their white clover crop was a "complete and utter disaster".
Yields normally at one tonne to the hectare were shredded to 200kg - unseen in his, or his 80-year-old's father's, lifetime.
New Zealand was the largest producer of white clover seed, and the bottom line was there would not be any available for pastoral farming, he said.
Meanwhile, fertiliser, diesel, agri-chemical and other input prices skyrocketed and, with contract prices already set, bottom lines were left bruised and battered.
Last season, the Birketts had about 40-50ha sown in malting wheat for the craft brewing industry, which yielded 13 tonnes per hectare - below average seasons of 13-14 tonnes per hectare.
Much of the low-yielding 40ha of white clover grown for seed is for the northern hemisphere multiplication market, with some going to domestic dairy farmers.
Ryegrass seed is the next largest crop at 30-40ha, with 10ha each in seed peas, and the same-sized area is reserved for beans.
Peas and beans are grown fresh for Watties processing, with about 15ha in hybrid radish seed.
Depending on test results barley will go for malting or the feed industry and a block in lucerne as baleage for the dairy market.
After some reflection, Birkett had decided to change little.
"We had a really good rethink about what we should change and the mix of crops and rotation, and we came back to the conclusion that the ratios we had were actually really good, sustainable rotations from a legume and wheat point of view, where you are using that nitrogen. And it's a bit like anything, if you chase the market you never catch it."
The Birketts could have put in a ratio with higher profit, but that would have come with a higher risk.
So they have resisted the temptation to put in more wheat but will plant less clover with this compensated by more beans being grown.
Milling wheat prices are on a high at about $650/t for free grain with some maize at $600, while free feed wheat is about $650/t so that could come into some growers' spreadsheets.
Birkett said they had settled on a proven system that provided a balance of environmental and profitable returns from their rotations - as long as contracts kept pace with their costs.
Their herbage seeds have contracts in place, but they have also grown more common varieties this season that can be traded openly on the free market and that includes Nui ryegrass because "the price is right" and it is still a good yielder.
He said there were side benefits of growing more ryegrass seed, but the profitability was not that good once the cost of production and "quite sobering" overheads of rising regulations, seed certification compliance, rates, insurance and inflation were broken down.
For example, the true cost of irrigating in Mid Canterbury would be more than $1000/ha once all the charges, maintenance and appreciation are added up.
Just a small combine harvester which could be bought for $250,000 10 years ago now costs $600,000.
Birkett said other seed crops needed the same price scrutiny because arable inflation would be north of 12 per cent this year.
He is among a group of farmers who pored through their books to find the true cost of production - and not just the gross margin of what is happening in the field.
They have just presented their findings to seed merchants and are awaiting their response.
They did not want to release the overhead numbers or the price they needed to the seed companies who they wanted to work alongside rather than against - but small gains previously of 20c-30c/kg wouldn't get them back to where they were previously, he said.
Birkett remained humbled to have been named Arable Farmer of the Year at a Christchurch ceremony this month in front of nearly 400 farmers and industry people.
"It's probably a culmination of things. We do things slightly different on-farm, but also do a lot of work within the industry in representative and advocacy roles as well as a lot in research and the industry."
As well as being one of four vice-presidents in charge of seeds in Federated Farmers' Arable section, he was chairman of the Foundation for Arable Research for seven years before stepping down three years ago.
He was also the inaugural chairman of the Seed Industry Research Centre and still sits on that board while continuing to represent the New Zealand Seeds Authority.
The farming system he has developed allows him to find time to do this work.
"I guess I've designed a farming system with lower work levels than the conventional, but I do quite enjoy that off-farm work and you meet a lot of people you learn a lot of stuff from that you can bring back to the farm too."
Birkett said he was proud of being part an arable industry with only a small group of 2000 growers that had set world records for growing.
