The evolution of Lamport AgX - 2022

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 in Agrovista trials, opening the door to further research to help drive down growing costs.

Niall Atkinson, Agrovista’s farming systems R&D advisor, says: “The objective was to maximise winter oat production at least cost per tonne. The beans were included as a means to reduce inputs, particularly nitrogen. But we actually applied no inputs at all except seed.”

The plot at Agrovista’s trials site Lamport AgX in Northamptonshire 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.

“The bi-cropped plot didn’t look particularly good for a while, but from May onwards it got better and better,” says technical manager Mark Hemmant. “In the end it 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.

Niall says the big question now is the potential for a long-term build-up of disease and pests, such as foot rot and stem nematodes in beans, from growing pulses too frequently.

“But, if you can grow this combination for no cost apart from seed, it opens up lots of questions,” he adds. “It may also be worth looking to see if other bi-cropping options can reduce the potential problems while cutting costs.”

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.

Latest results from Lamport AgX, Agrovista’s heavy-land trials site in Northamptonshire, show 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.

“This technique is particularly useful when growers find it a problem getting cover crops established in good time, particularly during a late harvest,” says Niall Atkinson, Agrovista’s farming systems R&D advisor.

Good establishment

“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.

“We’ve not had a lot of rain at Lamport since, so establishment was quite poor using the direct drilling,” says Niall. “By late September, the plants were mostly there, but some are very small, so my money would be on the blown-on cover at this stage.”

Light discing

While post-harvest direct drilling proved problematic in the dry summer, adding two shallow passes with 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.

“After several years of trials, our message now is that where we are establishing a cover crop post-harvest, moving a little bit of soil to achieve good seed to soil contact and to mineralise nitrogen will get the cover crop away in good shape.

“We might think we are doing more for soil health by direct drilling, but where conditions are not ideal we are probably better taking a small step back.

“The benefits of a vigorously growing cover crop will far outweigh any potential disadvantages caused as a result of a moving a little soil.”

Encouraging blackgrass

One disadvantage with blowing in a cover crop is the lack of shallow soil disturbance. At Lamport, a heavy land site with a very high background level of blackgrass, tickling the top cm or two has been found to be very beneficial in terms of getting blackgrass to chit so an effective kill can be made when the cover crop is desiccated.

“We don’t want to smother out blackgrass, we want it to be actively growing amongst the cover crop,” says Niall. “So we ran a straw rake through the growing cover crop on 20 September.

“We created quite a nice tilth that will encourage more blackgrass to grow. The rake did knock the cover crop back a little, but it quickly recovered and was growing strongly again within a week or so, along with a flush of blackgrass.”

Blackgrass-beating wheat rotations appear a profitable option

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.

Work at the heavy-land site also suggests that growers who want to maximise their wheat area could use spring wheat in sequence with winter wheat to maximise 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 (see box).

Results from harvest 2022 trials show that returning to a first wheat after a run of cover crops/direct drilled spring crops can produce exceptional yields, even on a heavy-land site such as Lamport with a background blackgrass population that exceeds 2000 plants/sq m.

“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.

“Before considering a return to winter wheat you have to reduce the weed seedbank to a low-enough level to give full-rate herbicides a chance to work. We know that even a stack containing the latest chemistry is not good enough where blackgrass numbers are high.”

Previous cropping on these winter wheat plots consisted of a black oat-based cover crop followed by spring oats in 2019/20, followed by a cover crop then spring beans last season.

The plots were direct drilled on 28th September at 300 seeds/sq m into a cheap linseed/berseem clover catch crop that was blown into the beans.

The first wheats received full-rate chemistry to control blackgrass – Proclus Liberator and Avadex followed by full-rate flufenacet early post emergence.

The winter wheat work is being extended to see whether wheat can feature in successive seasons to meet the needs of growers who want to maximise the crop on their land, particularly pertinent given the current price of wheat.

A second winter wheat is not part of the plan. Niall Atkinson, Agrovista’s farming systems R&D advisor, says previous experience at Lamport AgX shows second wheats undermined years of effort to control blackgrass.

Levels soared close to those seen a decade ago, decimating yields and margins.

“We are still looking at growing successive wheat crops, but we are asking whether we can grow winter wheat one year and an autumn-sown cover/direct-drilled spring wheat the next, and so on.”

The winter wheat plot in this case had been under a cover crop/spring wheat regime for the past four years. Mark says: “This plot yielded just over 11t/ha. This was slightly down on the other winter wheat plots that followed a more mixed rotation.”

“But over the years we’ve been achieving 7-8t/ha from a spring wheat after a cover crop at Lamport, so when we cost the successive wheat rotation it may well be the more profitable option.”

In addition, the system still provides the benefit of an autumn-sown cover, and a catch crop ahead of the winter wheat if desired, contributing to improving overall soil heath, says Niall.

“As a grower I like this idea, and economically it looks great. But I do have slight concerns about take-all.”

Mark says within the life of Lamport AgX and in this plot specifically, which has just had a run of cereals, he has never seen the disease.

“We think by breaking up the run of straw crops with black-oat based cover crops we’re breaking the take-all cycle, so we believe we can successfully grow a long run of cereals, plugging in winter wheat in the appropriate slots, in place of a mixed rotation.”

Lamport blackgrass control system

A sequence of cover cropping followed by spring cash cropping has achieved excellent control of blackgrass in crops at Lamport AgX over the past 10 years.

The technique uses a cover crop to condition the soil to enable spring drilling, but which is sown thinly into a shallow seedbed to encourage blackgrass to grow so it can be destroyed with the cover crop around Christmas.

This is followed by a spring crop, which is direct drilled to minimise soil disturbance and potential blackgrass germination.

“We’ve created a system that works fantastically well,” says Niall. “We’ve proved that it’s possible to grow successful spring crops on heavy, challenging soil while controlling blackgrass at the same time.”