Thursday, August 22, 2019

Farming in a changing climate

May 1, 2019 by  
Filed under Profiles

Farm manager and Nuffield scholar Russell McKenzie talks catch crops, cover crops and capturing nutrients with Judith Tooth.

April is getting drier – and August wetter, says Russell McKenzie, farm manager at John Sheard Farms Ltd in Bedfordshire.

Compared with 10 or 15 years ago, traditional April showers have yielded nearly 30 per cent less rainfall the past three or four years, and hitherto sunny Augusts – with the exception of 2018 – have been 25 to 30 per cent wetter.

“It’s a challenge for us: two key months, one that’s essential for crop growth, getting drier, and the other, when we want to be getting the crop in, getting wetter,” explains Mr McKenzie.

“We’re at the stage now in our blackgrass control where we don’t drill a reasonable percentage of our wheat until the second half of October,  that’s proving very reliable and gets the best out of herbicides.”

Even so, growing good crops still needs the weather to be on side. “Mainly where we are direct drilling, if it’s too wet on the surface, the soil can be slimy and buttery rather than friable and crumbly, and we can get poor slot closure.

“That’s where catch crops can help: the living roots are pumping water out and help to dry out the surface. The tricky bit is making sure the catch crop is not too thick or it shades out the blackgrass when we spray the crop off. We use a very simple mix of oil radish, phacelia and linseed, or rye and mustard.”

Cropping strategy

Mr McKenzie grows wheat, oilseed rape, winter and spring barley and beans, and spring oats on predominantly heavy clays in undulating countryside between Bedford and Huntingdon. Seed crops make up a quarter of the annual harvest: wheat and beans for Dalton Seeds and wheat for Frontier.

“I like being innovative, particularly with seed varieties, so, for example, we’re growing KWS Kinetic, which is due for recommendation this year. It’s a bit of a gamble but if it does well it will be a step up in yield.”

Mr McKenzie is also growing KWS Firefly and Extase which this time last year looked very good in terms of disease package. Varieties tend to turn over a lot more quickly than they used to, he says, and he likes the opportunity to get in early.

“Kielder, for example, didn’t really take off nationally, but it produced massive yields for us during the time we grew it. I probably wouldn’t grow it now because of its disease rating.

“Good disease resistance is a big factor: I don’t want to be chasing yellow rust or septoria. A variety with a good disease package that’s only one or two per cent behind the high yielder with poorer ratings is a better bet.”

It’s getting harder to push yields of oilseed rape now: four or five years ago they were averaging 4.5t/ha; now Russell is struggling to get four.

“The crop gets established and then we find [flea beetle] larvae in the stems. Then the crop doesn’t grow quite as quickly – and a bad infestation can lead to a 40 per cent drop in yield. But it’s still an important part of the rotation.”

Cover crops are also used in the rotation, with 40ha first grown ahead of spring crops four or five years ago.

“We’re moving towards no-till, so we want to keep the soil structure in place and be able to move water round in a wet season. And if there’s a lot of growth, we bring in a grazier, which works well – though we don’t want overgrazing.”

Different mixes

With growing experience, choice of cover crop is becoming easier: multiway mixes are great, but expensive, and rye or oat based mixes, because they can lock up nitrogen, would be suitable in front of beans, as they don’t need nitrogen to get away quickly, but more diverse mixes are used in front of spring cereals.

“I really like phacelia as a component, as it’s very fibrous, so really opens up the soil profile. That, and vetch, oil radish, linseed and sunflowers.”

Mr McKenzie is also seeing encouraging results capturing nutrients: comparing soil mineral nitrogen in a split field, one with a cover crop, the other without, he found the cover crop capturing 37-40kgN/ha. “So environmentally it’s a good thing, but that’s different to knowing when that nitrogen is going to be given back to the land. It looks like the release is two years later.

“We’ve been lowering our nitrogen requirement, so whereas before, for an 11t/ha crop of wheat, we were using 220-230kgN/ha, we’re now using 190 or 200kg, and in some of the longer term no-till fields, 180kg.”

Of the five farms across 995ha managed under John Sheard Farms Ltd, three, including Hoo Farm, are now predominantly no-till. The other two are “nowhere near”, still needing more cultivations as their soils are not holding their structure naturally.

“Performance counts for a lot, and there’s no point being dogmatic. We have a flexible, open-minded approach.

Nuffield scholar

A Nuffield scholar in 2014/15, Mr McKenzie travelled to Australia, New Zealand, the US, Brazil and Argentina, visiting some very early no-till adopters in areas of low and high rainfall to look at ‘success with no-till under any conditions’.

“How could I relate what I found to here? Mindset is the important bit: being positive and being prepared to challenge what you are doing. Resilient soils and soil organic matter are the key, but this doesn’t build up overnight.”

His choice of drill is a Horsch Sprinter with two different points: flexible Dutch openers and Bourgault VOS openers. Although it takes a couple of hours to change the points over, it offers a lot of flexibility, and the Bourgault openers have transformed oilseed rape establishment.

Three farms are in Mid Tier Countryside Stewardship, with a mix of grass margins, especially along watercourses, which help with varying buffer zones for pesticides; whole fields down to two-year grass and legume fallow, building fertility in less productive areas as well as helping with blackgrass control, and pollen and nectar mixes where yield maps indicate less productive areas.

Future plans

“I dipped my toe in gently, and the more I understand the scheme the more I see I could have been a bit braver. We could have taken larger areas of fields out, put in more margins. But we’re certainly a long way from the days of farming up to the edges of fields.  Environmentally it’s good, and we get a reasonable return.”

Looking ahead, the goal is to further reduce costs. From two crawlers and five tractors when Mr McKenzie joined as farm manager nine years ago, there is now one crawler and three tractors – with the farms spread out, it would be hard to reduce that number further – and annual diesel usage is down by 17,000l.

Seed dressings are under scrutiny: if the seed is tested each year, does it need dressing? Varietal choice is focused on disease resistance, particularly options that could reduce fungicide use.

“Herbicide costs have fallen with no-till and there is less blackgrass. It’s very difficult to be definitive – we can trim away at variable costs, but really it’s like chipping at an iceberg. But the big cost is fixed costs. We can run machinery for longer but don’t want repair bills to overtake the cost saving.”