Lamport AgX, Agrovista’s flagship trials site in Northamptonshire, continues to push the boundaries to help growers produce profitable crops on heavy land, despite high background blackgrass populations. Here are some tasters from this year’s findings.

    Profitable September-sown winter wheat crops can be grown long-term on land with a history of serious blackgrass infestation, according to the latest results from Agrovista’s flagship trials Lamport AgX.

The findings also suggests that growers who want to maximise their wheat area could use spring wheat in sequence with winter wheat to increase profits.

However, in both cases great care must be taken to minimise blackgrass germination throughout the rotation, notably by using a sequence of cover crops and spring cropping.

Results from harvest 2022 trials have shown that returning to a first wheat after a run of cover crops/direct drilled spring crops can produce exceptional yields, provided the weed seedbank has been reduced to a low-enough level to give full-rate herbicides a chance to work.

“First wheat yields this harvest ranged from 12.45-13.39/ha when following Lamport best practice,” says Agrovista technical manager Mark Hemmant.

“We counted less than 1 blackgrass head/sq m in these trials, which shows what can be done.” But growers have to stick to the guidelines or risk going backwards with blackgrass control, he adds.

This work is being extended to see whether wheat can feature in successive seasons. A second winter wheat is not part of the plan, as previous experience at Lamport AgX shows second wheats undermined years of effort to control blackgrass,

with soaring levels decimating yields and margins. Instead, the focus is on growing winter wheat one year and an autumn-sown cover/direct-drilled spring wheat the next, and so on.

The results so far have been very favourable, says Mark. “We achieve 7-8t/ha from a spring wheat after a cover crop at Lamport, and the winter wheat we harvested this year, which followed four years of cover crops/spring wheat, yielded just over 11t/ha.

“This was slightly down on what was seen in a more mixed rotation, but when we cost the successive wheat rotation it may well be the more profitable option.”

Pre-harvest cover crop establishment proves a success

Good establishment of cover crops is vital to maximise the soil health benefits they offer. But achieving a good plant stand is often difficult, given that sowing often coincides with the busy harvest period as well as bone-dry soils.

Work at Lamport AgX clearly demonstrates that blowing a cover crop into a standing crop of wheat a few weeks ahead of harvest can mitigate both those problems and produce good results.

The cover crop consisted of Phacelia, buckwheat, linseed and berseem clover.

Niall Atkinson, Agrovista’s farming systems R&D advisor says: “You have to pick your moment. You want to wait for a little bit of moisture to help seeds establish, but you can go between four and six weeks ahead of harvest so there is a reasonable window to wait for a little bit of rain.

“Even in the dry summer we’ve just had, we achieved fairly good establishment and plants have moved on well.”

A further advantage of blowing seed on at this timing is that the wheat straw provides a mulch for the young cover crop. The benefits were obvious this year; another cover crop plot that had been straw-raked once then direct-drilled on 18 August into the wheat stubble has struggled in the dry conditions.

However, adding two shallow passes to the post-harvest technique using a light disc cultivator (Simba X-Press) between straw raking and drilling made a big difference.

“Moving a bit more soil created a better seedbed and we achieved a nice even establishment of the cover crop and good blackgrass emergence,” says Niall.

Zero-input oat crop hits the heights

A crop of oats grown with no inputs apart from seed and a companion crop of winter beans has produced an exceptional yield at Lamport AgX, opening the door to further research to help drive down growing costs.

The plot follows several years of cover crops and spring wheat to get on top of blackgrass. The beans were direct drilled on 28 October 2021 at 38 seeds/sq m, followed by the winter oats at 340 seeds/sq m on the same day – full seed rates for both crops.

A conventional plot of oats alongside received 120 kg/ha N and commercial applications of pre-emergence herbicide, fungicide (x2), growth regulator and herbicide.

Mark says: “The bi-cropped oats yielded 9.36t/ha of good quality grain, only 0.5t/ha short of the conventional crop, and we got 0.42t/ha of beans into the bargain.”

Nitrogen offtakes were almost exactly the same for both plots of oats – 193kg/ha for the conventional plot and 191kg/ha for the bi-cropped oats, showing the effectiveness of the beans in supplying nitrogen.