Light land wheat trials point the way to better yields this autumn, as Farmers Weekly discovers

Improving the resilience of winter wheat on light soils could help combat the type of stress being seen in many crops in the current hot spell and this is the aim of a series of trials being carried out by Agrovista.

Hotspots in light land wheats have been spreading rapidly over the past couple of weeks, potentially bad news for both yield and quality.

It’s a problem with which John Barrett, marketing manager for Sentry Norfolk, is familiar. About a third of the 22,000ha farmed by Sentry Farms is prone to such problems when drought strikes.

“Maximising margins on these areas is key for our business,” says Mr Barrett. “We asked Agrovista three years ago to help us manage these crops better to deliver more reliable yields and quality.”

The linchpin of the management plan is early drilling, to encourage a well-established root structure that is better able to withstand the effects of drying soils, says Mark Hemmant, technical manager for Agrovista.

Work carried out by Agrovista 15 years ago had shown that using low seed rates on light land could improve yields. The current project, in conjunction with Sentry and plant breeder KWS, was set up to re-examine the technique with more modern varieties.

At the Denham Estate, near Bury St Edmunds, Suffolk, large farm-scale (24m wide) plots have been established on the sandy, stony loams over chalk.

Early-sown varieties include KWS Santiago, Horatio and JB Diego were drilled on 7 September and KWS Kielder sown six days later. Two different sowing rates were used, averaging 115 and 176 seeds/sq m. Later-drilled varieties Conqueror, KWS Santiago and KWS Solo were drilled on 15 October at 350 seeds/sq m as a comparison.

Visual observations suggest there will be some big differences come harvest, backing up some earlier findings from two very contrasting seasons, says Mr Hemmant.

By early July the earlier-sown plots generally appeared more consistent, with better, more robust stands, notably the low-seed rate JB Diego and Santiago. Mr Hemmant tips Santiago as the potential winner this season, based on its current and previous performance.

Two years ago, despite yields being capped by drought, early sowing increased yield by an average 0.52t/ha across all varieties on another Suffolk farm managed by Sentry, at East Bergholt. Santiago topped the list, achieving 7.37t/ha sown at 110 seeds/sq m on 9 September.

“Normally you wouldn’t choose this variety as an early driller,” says Mr Hemmant. “It develops quickly and is a vigorous tillerer, but the light land took the edge off it. Rooting was much improved and the crop was able to sustain tillers in the very dry spring.”

A 2012 trial at Askham Bryan in North Yorkshire produced similar findings. Early sowing produced an average increase of about 1t/ha, with Santiago yielding just over 10t/ha from a 5 September sowing at 135 seeds/sq m, pipping JB Diego by 0.3t/ha.

However, in a similar trial near Langham in Suffolk, late-drilled plots yielded similarly or slightly higher than the earlier-drilled ones. That confirmed the benefit of low seed rates, but without the additional yield. Santiago again produced the best early-drilled yield at 9.6t/ha, matching its later-drilled performance, while late-drilled Conqueror topped the trial at 10.3t/ha.

“There was very little disease in the Yorkshire trial last season,” says Mr Hemmant. “However, in Suffolk it was exceptionally wet. Fungicide timings were compromised in the trial and even the best programmes couldn’t keep on top of disease. Crops over-tillered, even at the low seed rates used, and there was quite a lot of disease in the early-sown crops by late February.”

Overall, results confirm that early sowing on light soils can significantly improve yields, and that the technique requires a lower seed rate and different management, says Mr Hemmant.

Early sowing brings risks, so anyone adopting it needs to manage the crop correctly, says Matt Bell, farm manager at Denham Estates. “It is not just a commitment to sow early – if we want to see a 1t/ha difference then we need to manage the crop accordingly so it can reach its potential.”

Over-yeared home-saved seed is likely to be needed to ensure availability. It should be Deter-dressed, and a routine follow-up pyrethroid spray to control barley yellow dwarf virus should be applied, he says.

Good grassweed control is critical, and stacking residuals pre-emergence is a must, says Mr Bell.

“While there is significant grassweed pressure from early sowing, I believe if you get the full pre-emergence programme on to what will be a competitive crop, that is better than leaving drilling until later and risking not getting pre-emergences on to a thinner crop.”

Jury still out

While choosing a more vigorous variety than usual for light land early drilling might make sense, the jury is still out, says John Miles, product development manager at KWS.

Traditionally, early drillers on better-bodied soils look for slow-developing wheats with good standing power, good eyespot resistance and good specific weights, he notes. “So we still look at short, stiff varieties such as Claire, Grafton and Scout as the textbook varieties.” Whether they perform on light soils is less certain – indeed Grafton was ruled out in 2011, says Mr Miles.

“There seem to be elements of drought tolerance within varieties that aid performance, though we haven’t nailed it yet.” However, later-maturing, taller and vigorous varieties such as Santiago, which can afford to lose a few tillers, appear to excel in the early drilling slot in dry conditions and/or when disease pressure is low, he adds. The variety also performed well in 2012.

Light soils appear to be restricting its growth to manageable levels. “Santiago is not an early driller on paper, but it has worked well in a wet and a dry season. It has been consistent, and these sorts of varieties are certainly worth evaluating further,” says Mr Miles.

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