8 September 2001

All even stevens

It can be hard to pick out the differences in the Arable Event establishment demonstration at the Cereals 2001 site, but herein lies the significance. Tom Allen-Stevens joins the post mortem

IF YOURE weeping at your wheat yields and your pitiful pile of oilseed rape brings tears to your eyes, spare a thought for those struggling to make sense out of their trials results. The ideal trial demands perfect conditions so that the criteria on test can deliver the true results at harvest without any errors creeping in. That hardly describes this years round of trials.

Keith Norman, Velcourts technical director, has been puzzling over the Arable Event demonstration that has taken place at what was supposed to be the Cereals 2001 event site. The results are now in and Mr Norman finds the main problem is deciding whether any conclusions can be drawn from them.

Perhaps the fact that they were brought to harvest at all is a blessing: the cancellation of the event because of foot-and-mouth disease put the future of the whole site into jeopardy. But with the co-operation of the Arable Event sponsors, Banks Cargill, Monsanto, Simba and Case, Mr Norman transferred them to the internet. Their progress has been posted onto the FWi site, the interactive element of Crops and Farmers Weekly, ever since.

Part of the event was a series of establishment plots, where ploughing has been pitched against min till and early drilling against plots planted eight weeks later on. The interesting conclusion is that there is no definite yield benefit either way: "There are as many differences in yield one way as another, so you could say all the plots are pretty much even stevens," says Mr Norman.

But he has been able to draw some conclusions about the varieties used, although he is keen to stress that these were not replicated trials, so differences could just be anomalies. These were chosen according to their suitability to the two drilling dates – mid-September and mid-November. Consort, Claire and Oxbow were drilled early, with Charger, Option and Malacca going in late.

It is the very fact that there is not much difference between their performance, despite being drilled so far apart, that is one of the key findings of the trial, Mr Norman says. He underlines the importance of choosing the variety carefully to match the situation: "Choice of variety is key. You can make up a lot of lost ground at a later drilling date by choosing one right for the situation – Charger, for example, perfoms well in this slot."

What has surprised Mr Norman and trials supervisor Ben Corbett is the lack of difference between ploughing and min tilling. During senescence differences showed up between the ploughed and direct drilled plots: "The plants in the late-drilled ploughed plots hadnt rooted very well. They suffered during those dry spells in May and June," reports Mr Corbett.

Fissuring

The way the ploughing was carried out may have much to do with it, he believes: "It was all done on the same day. With all the rain, the November-drilled block had gone sad – all the soil had run together and did not drain freely. The seed was a little bit muddled in."

But even at the later date the financial results show there is very little difference between the ploughed and min-tilled plots. Mr Norman points out there are still plenty of other practical benefits of reducing cultivations, however: "You can achieve a much higher work rate, which is especially important in a catchy season. This makes optimum drilling date targets more attainable."

Nor were there any conclusive differences with nitrogen application. The total dressing of nitrogen was the same over all the plots, but some have it split into two doses, while others have four applications. Mr Norman explains the theory: "We wanted to see if you need a different nitrogen management system for a later drilling date. The logic is yes, but we wanted to prove it.

"The later-drilled wheats should benefit from a four-way split, while the earlier wheats should be happier with two doses. Its all in relation to root structure. The well-developed early-drilled plants should be able to exploit the soil mineral nitrogen more readily, giving better growth and vigour. The higher root mass would be able to intercept larger doses of N. The later-drilled plots should need more careful nurturing, however."

The lack of definite trends to pull out has surprised Mr Norman: "There seems to be no diffference between two and four splits, and this in itself has some fairly major implications at farm management level. If you can get away with two passes it frees up machinery and labour resources; you can cut down the number of passes on the later-drilled wheats, although the starting date is still very important."

Overall, results from trials on Recommended List candidates and non-recommended wheats have been at best inconclusive and at worst perplexing. "The results for Storm and Xi19 are rather difficult to explain: the control plots performed better than the managed plots." The very low levels of disease this year has meant response to fungicide has been very variable, he reports. Variation in soil quality may also help to explain the strange results.

But yields have been very low, and this does concern Mr Norman. "Everyone who saw these trials was impressed with how good they were looking and with their yield potential. I would have expected at least another 2t/ha, especially from the Recommended List candidates."

Most of this is down to the site, soil type and season, he says. "This exposed, light land site suffered in the dry spells. Elsewhere heavy soils have never forgotten the effects of last autumn. On free-draining fertile soils under this management regime this new genetic material has performed much better."

And here is the final lesson Mr Norman has gathered from the results this year: variety choice can help tweak a situation, but cannot deliver miracles.

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