Prioritise conditions over cultivations when making variety choices, new Agrii trials suggest

Latest Agrii trials suggest while clear differences can be seen between varieties in various production scenarios, there is little to separate them when it comes to their performance in direct drilling or conventional cultivation systems.

Varieties and how they perform across a range of production scenarios is a key element of Agrii’s integrated crop management (ICM) programme, says the company’s head of integrated crop technologies Dr Ruth Mann.

“All trials work at Agrii is designed to provide growers with vital information on how to manage the ever-changing range of crop production systems, with varieties right at the heart of this,” she points out.

“The aim of all our R&D output is to deliver on every farmer’s triple bottom line and ensure yields and profitability are optimised without detriment to the environment.

“Identifying the optimal variety for sustainable cereal production is an essential part of any ICM programme, but it has not always been clear whether varieties perform the same in all situations.

“In particular, one of the big questions of recent years has been around varietal performance in direct drilling versus conventional ploughing systems, and our current work is providing vital insight into this.”

According to Agrii seed technical manager John Miles, the latest indications are that growers should choose varieties that are likely to deliver the best performance in their individual locality and growing conditions rather than trying to identify which ones suit their cultivation system best.

“Two years of trials across two different locations with both direct drill and conventional cultivation systems have shown no statistical proof that some varieties suit one approach better than the other,” he explains.

“The theory was that because there is potentially low mineralisation in direct drill soils as they are not being disturbed, a nitrogen poor scenario creating slow growing crops could result, with some varieties coping better with this than others.

“Equally, some direct drillers may choose to sow a bit earlier as they are not being held up by cultivations, so that too could affect what type of variety would do best. Many producers looking to switch to direct drilling from ploughing, therefore, ask the question which varieties are likely to deliver the best performance in the new system and there has been a lot of debate about this over the years.”

The Agrii trials took place at sites in Huntingdon and Braintree, with both locations deliberately featuring hanslope series clay soils representative of 35% of the UK’s arable area, John Miles explains.

“Heavy clays tend to be more of a challenge when moving on to direct drilling, but they are representative of many of the soils found in the East of the country. For both sites and years the same range of 18 popular RL wheat varieties was used.

“The Huntingdon location was on a farm where direct drilling has been practiced for the last ten years alongside integrating cover crops, whilst at Braintree continuous wheat has been the approach for 40 years, but direct drilling is now being looked at to save costs.

“Because of the expected higher losses at establishment from direct drilling, it was decided to up the seed rate from the 350 seeds/m2 of the conventional approach to 425 seeds/m2 for the direct drilled plots, to ensure even plants stands.

In both years across both sites, plant and ear counts were roughly the same for direct drilled and ploughed plots, showing the extra 75 seeds/m2 had helped create the level playing field across all plots that we had hoped for.

Direct drilling challenges

Results from the Braintree site for 2022 showed average yield of the plots that were direct drilled was 8.9t/ha compared to 9.5t/ha for the ploughed ones – a 0.6t/ha difference.

“KWS Zyatt, KWS Extase, LG Skyscraper, KWS Dawsum, Gleam, and DSV Theodore all did well in the direct drill situation with yields of 9.0t/ha and above, but these are the same varieties that did well in the ploughed situation, too, with some topping 10.0t/ha.”

Highlighting some of the issues with direct drilling, the overwhelming reason the ploughed situation yielded higher was because the actual area of crop harvested was less in the direct drill plots, John Miles explains.

“Although all the straw was removed from the trial field, there was regrowth out of the back of the combine, and all it took was drilling on a wet, foggy morning to result in poor establishment. This was not helped by the significant slug pressure created by the level of residue even in a wheat-only rotation.

“You can see similar areas in the farm’s other fields, with crop density getting noticeably thinner in those areas, but a trial drill goes slower than a normal drill and doesn’t have the same weight to it, so the problem is more evident.

“That said, it is indicative of what can happen when you are drilling into residue. It’s often the case that you end up with a sub optimal plan stand which in this case was seen as a bare stripes across all the replicates. The yield difference between the different approaches was, therefore, largely because the direct drilled area had some bare patches in it rather than actual differences in the crop.

In 2023, establishment was even in both crops and the final yield results closer too, he explains.

“Conditions were too challenging to plough, so the cultivated plots were heavily disced a couple of times instead, but throughout the growing season, it was difficult to see a difference between the plots.

“In the end, average yield difference was only 0.4t/ha between the different approaches, but again those varieties that did well with direct drilling, also performed well in the cultivated scenario.

“There was marked difference in performance between the different varieties at the site, but nothing that would suggest a better result for one variety over another between the two approaches.”

Ploughing problems

At Huntingdon, in 2022 all plots established relatively evenly, but the ploughed ones started losing biomass because of the high rainfall in January that year, John Miles explains.“

In contrast, it was probably the kindest start possible for the direct drilled plots as it was after oilseed rape, without much trash and a cover crop that was sown with a drill featuring large tines that helped break up the surface. “Unsurprisingly, direct drilling outyielded ploughing in this case to the tune of 0.6t/ha, but in view of what we saw in February with the biomass, that is probably not too much of a surprise.

“Similar conditions were seen in 2023, where once the ploughed areas got wet in the winter, they stayed that way, with a correspondingly lower biomass in February. But we didn’t get the subsequent prolonged drought seen the previous year, so the ploughed plots did recover somewhat.

“But the direct drilled plots still yielded on average 0.7t/ha more than their ploughed counterparts. Again, the varieties that performed well in the RL that year – KWS Extase, KWS Dawsum, Gleam and Graham – were the ones that delivered the highest yields across both approaches.”

Basically, at one site the plough won the day and at the other site direct drilling worked better and this was consistent across both years, he points out. “Subsequent analysis shows that while differences between varietal performance at each site are significant, there is no correlation between any variety and its ability to do better or worse in direct drilled or plough-based production systems.”

“While there is some truth that in some circumstances, such as when drilling into cover crops, incorporated straw or in challenging weather, a more vigorous variety could help with establishment, our results suggest this is much more to do with conditions than cultivations.

“A high vigour variety could well compensate later for poor early establishment, grow through slug attack better in adverse conditions or simply thrive better in cold, wet soils, but this would be the case regardless of farming system.”

No difference

By and large, a variety that does well in a ploughed situation will do well in a direct-drilled scenario, John Miles concludes.

“Even if we had been able to identify a difference in performance in varieties between ploughed or direct drilled systems, it is likely it would be so small as to make it barely worth considering. It would certainly lie outside the top five considerations.

“In other words, all the current reasons why you choose a variety for your particular situation – yield potential, disease resistance, standing power etc. – would outweigh any suitability to cultivation system.

“Ultimately, the ability of a variety to perform in any farming situation is down to conditions encountered at establishment and throughout the growing year and not its suitability to any one production system over another.”