14 May 1999

Sep sowing will maximise 21t/ha

wheats

MAXIMUM profit from wheat comes from early drilling, with a 21t/ha yield potential within the reach of UK growers, claims Ryehill Farm Services.

But technical expertise and understanding crop physiology are essential, says director, Ian Chalmers.

Cutting the cost a tonne by targeting top yield is the linchpin of his philosophy. "Wheat needs to be sown early to realise the genetic potential of the seed," he stresses.

For modern wheats that genetic potential is about 21t/ha (8.5t/acre). Yet good growers are only reaching 10t/ha (4t/acre) and the UK average is about 7t/ha (2.8t/acre).

"What are we doing wrong?" he asks.

Early establishment and variety choice are the key. Drilling should be Sept 5-25, allowing for the length of the local growing season.

"In the north that can mean planting next years wheat before the current years crop is cut. And the seed-bed must be fine, firm, and moist. If a grower cant achieve these three things together then do not drill it. I want to see early sown crops through the ground in four days," he says.

Development characteristics are the main determinant for variety choice. Suitable varieties continue to develop ear primordia late into spring, preventing plants becoming too advanced, and producing large numbers of grain sites an ear.

Early developing varieties are not suitable for early drilling as they go into stem extension too soon, risking frost damage to the ear. Blind grain sites result in disappointing, if not disastrous, yields.

Short, stiff straw, good disease resistance including eyespot, and high ear fertility are other traits Mr Chalmers looks for in an early driller.

By sowing early, plants have more time to put down deep roots, mopping up residual mineral nitrogen that might otherwise be leached. Then in the spring the plants emphasis switches to top growth, and the deeper root system reaches more nutrient and moisture to produce a greater above ground biomass.

Mr Chalmers advocates testing soil cores for mineral nitrogen down to 90cm depth under such early drilled crops. The fertiliser requirement is then calculated working on 23kg of nitrogen a tonne of target yield, typically 12t/ha (4.9t/ha).

Dedication is needed to get crops in so early, he says. "Growers need to be mentally focused and on a war footing as soon as they start harvest. Crops can go in within 24 hours of harvesting."

Seed rates must be cut to prevent over-thick crops in spring, and autumn protection from virus carrying aphids is essential. But early sowing does buy time later in the year, with wider spray windows, Mr Chalmers maintains.

"For example GS31/32 may last for eight weeks because the crop reaches that stage when the weather is colder. Last year many people struggled to get T1 fungicides on because of the wet April but on our early drilled crops we were finished with T1 by then."

Nothing a grower does to a crop after it is planted adds yield, it just prevents yield being lost, he adds.

EARLY DRILLING

&#8226 Key variety attributes:

– Late developing.

– Short stiff strawed.

– Good disease profile, inc eyespot.

– Highly fertile ears.

&#8226 Use all management tools.

&#8226 Timeliness essential.

&#8226 War footing to get crops in.

&#8226 18t/ha grower claims, 12t/ha regularly.

Super resistance?

A NEW wheat variety in second year national list trials shows even later primordial development than Claire, and has an exceptional disease profile, claims breeder Nickerson.

"Its rating for septoria resistance would be a nine," reckons Bill Angus. Codenamed WW20, it will particularly suit very early drilling or conditions in the south and west. But general NIAB recommendation seems unlikely as yield is only on a par with current varieties, he says.