28 May 1999

SQUEEZING OUT MAXIMUM YIELD

CEREAL yields need pushing to offset production costs. And they can be pushed on all soil types, provided the latest understanding of crop husbandry is adopted in full.

"The scope for pushing yields is greater on heavy land than land light," says ADAS agronomist David Parish. "But every field really has the potential to deliver more yield, if the latest crop physiology findings are correctly used."

However, making the most of those findings demands a clear appreciation of the processes involved and a commitment to make significant change to crop husbandry practices, he notes.

"There are real dangers in adopting a small part of the new advice and not the whole philosophy. Growers can find they are no better off."

Early drilling is a prime example. "Everybody knows early drilling can raise yields. But it will only give the full yield benefit if the right varieties are chosen, the right seed rates used and the following crop husbandry adjusted accordingly.

"Fail to do that and you could run into trouble, as some growers experienced with excessively dry seedbeds and widespread lodging in recent seasons.

"Last year some of those that had their fingers burned in previous years refused to drill before the end of September. They then got 4in of rain in two weeks, which delayed drilling severely, all because they failed to appreciate the husbandry needs of early drilled crops."

Early drilling stimulates tillering, which increases lodging risk. So seed rates need reducing, Mr Parish explains. But that must be in line with seedbed conditions. In adverse conditions rates may need to be a little higher to provide the desired plant population post-winter.

Variety also has a key role. "Many farmers are still not fully aware of this."

As well as looking for low lodging susceptibility, growers should seek slow developing varieties, like Riband and Consort. That will help avoid the risk of late spring frost damage and will also optimise grain fill.

Each extra day of grain fill in summer gives an extra 0.2t/ha of yield. Crops that enter the grain filling period during cooler conditions keep filling grain for longer.

"The trick is to choose a variety which flowers early, but not too early, or late frosts could cause trouble."

But a dearth of reliable variety information can leave growers confused. "The recommended list says nothing about suitability for early drilling and there is very little else published."

There is also some false information coming out of some organisations. "It is not just development speed relative to temperature that matters, but speed relative to day length too.

Early sown Spark, for example, responds very slowly to temperature in the spring. But it can get very forward very quickly going into the winter, which can risk crop damage."

Timeliness vital

Timeliness of operations is also crucial. Optimum application windows need observing to make the most of modern crop inputs, which can be very sensitive to the application conditions and growth stage of the crop.

That is where attention at drilling time can bring big benefits. "If you can spread the drilling window through the choice of varieties you could get away with a smaller drill, or use the same drill across more acres, so cutting costs. It could also spread application windows, easing spring spraying, and spread the harvest, all reducing the peak workloads and so reducing labour and machinery costs."

Crop monitoring and an understanding of disease development is also needed to ensure appropriate input use. "Riband always carries more Septoria at T1 than Hereward. But the amount of Septoria seen is not a good pointer to the optimum fungicide rate.

"A lot of farmers are leaving the responsibility for such decisions to their agronomists. But we take the view that some agronomists can focus on inputs too much. It is equally important that crop growth and development is monitored to ensure optimum use of inputs.

"The key is to manage crops differently, not with more or less inputs. They need managing according to their potential and what they need and that demands a much better understanding of the way they develop and how that influences their individual needs," Mr Parish concludes.