Archive Article: 1997/07/05

5 July 1997




ESTABLISHING rape on heavy land is not easy. Many growers had a nail-biting wait, before crops emerged from parched seedbeds last autumn. Eventually some fields had to be patched with spring rape.

Growing 75ha (185 acres) of rape on predominantly chalky boulder clay at the 425ha (1,050 acres) farmed by B F Whitlock and Son, Brook Farm, near Swineshead, Beds, Michael Whitlock and his ADAS arable business consultant, David Parish, reckon they have the measure of the problem. This season they have established good crops following wheat, winter barley and set-aside – despite the autumn drought. This is how they did it:

After set-aside

This is the easiest and most reliable entry. In previous seasons Mr Whitlock has ploughed early, power harrowed, rolled and then left the tilth to weather, spring tined, then drilled – but not last autumn. "We were worried about it drying out," he says. It was sprayed with glyphosate (Roundup) and ploughed at the end of June, then power harrowed and rolled immediately, but the seedbed was still too cloddy for comfort.

"Usually set-aside land ploughs up fairly moist, because it hasnt had a crop on it to pull out the moisture. But this time it wasnt quite right." So Mr Whitlock braced himself for the extra expense and a week later, power harrowed and rolled a second time – "unheard of, for us!"

Rape was drilled on 15 August, with spring tines going in front of the drill. It was rolled the same day, and helped by 20mm of rain emerged virtually straight away. This crop now looks the most promising, reckons Mr Whitlock.

"If the seedbed is right, we prefer to drill straight away to catch any rain that comes. If it is still a little cloddy, then we may have to risk it, and wait for rain to break it down further, before drilling."

After wheat

With some early maturing Soissons in the rotation, there were 12 extra days to prepare a seedbed, compared with that following conventional wheats. He went in with the combine on 4 August, and ploughed the same day.

The next day it was power harrowed and rolled – leaving a "reasonable" seedbed. But because the crop had removed soil moisture, it was still too dry – "there was 8in of loose dry clods, with too much air."

However, Mr Whitlock went ahead and drilled on 15 August, with spring tines again ahead of the drill. There was a huge contrast in emergence between the rape following set-aside and that following the Soissons – despite being drilled on the same day.

"I spent the next month walking over it, wondering whether a crop was going to emerge or not," he remembers. A little nitrogen – 30kg/ha (37 units N/acre) – went on during mid October, to give the crop a boost. In the event the rape did eventually establish well enough to allay his concerns.

Where rape followed conventional wheats, the combine went in on 16 August. "Although short of moisture, the soil was in excellent condition – the best Ive seen. It was as friable as you could wish for."

There was a delay – as a result of a cropping change – and it was ploughed on 2 September, primarily to bury the straw. It was then power harrowed and rolled. The tilth was "excellent" though dry, so Mr Whitlock drilled on 5 September. It was then harrowed and rolled, in order to achieve as tight and as fine a seedbed as possible.

"Then we prayed for rain." Again, the crop had N during mid October. To protect plant numbers, slug pellets and cypermethrin against flea beetle were given.

It wasnt until April that Mr Whitlock could relax. Now the rape looks good, despite late emergence. "It has surprised me," he admits.

After winter barley

Combined on the 22 July, the winter barley straw was baled on contract – an operation that slowed up the cultivation programme when rain stopped play.

"We were nervous about the straw, and felt it was too fluffy and bulky to manage." But it meant a delay. Medium-weight Simba discs could not be sent in until 1 August.

With hindsight, Mr Whitlock reckons he should have disced twice, or even three times, to improve stubble incorporation. After discing, the land was rolled, spring tined and then drilled (14 August).

"We struggled to get the drill through, because of the remaining stubble. We removed the tines behind the drill, as there were times when it started to bung up." So the harrow was sent in after drilling to make sure that any seed fell out of the straw and into the soil. It was then rolled, and slug pellets applied.

A lot of stubble was still visible, but the rape emerged as quickly and as well as that following set-aside, probably because the ground was firm after disc cultivation, suggests Mr Whitlock. It was given early nitrogen.

In a wet autumn, ploughing would be the best entry, says Mr Parish. But in dry conditions, discing is the best solution following barley and wheat. However, the downside can be large numbers of volunteers, and barley can be particularly competitive.

Which rape will do best? That following set-aside, predicts Mr Whitlock – "but not by as much as we might have expected earlier!"

A good start is more than half the battle. Gilly Johnson visits a heavy land farm to find out how to establish rape in dry conditions.


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