The Yield Enhancement Network (YEN) was established by ADAS in Britain in response to the continued stagnation in cereal and, in particular, winter wheat yields there.

The aims of the project were to study commercial crops and examine the various factors that seem to affect yield levels and comment on each crop in respect of its ability to deliver that local potential.

Its objective is to strive to narrow the gap between current field yields and potential yield. It is doing this by encouraging an individual or organisation to get involved with the project and to share information with the organisers to enable them to study the causes of the gap between field yield and yield potential.

The organisers have identified this gap in yield potential and their objective is to study this large unfulfilled potential for growth and yield formation.

The biophysical potential of crops is influenced by incident light energy, rainfall amount and soil water storage.

In this regard, they indicate that much of the land in the UK is capable of yielding around 20t/ha of grain. And while leading farms and research trials often achieve 12t/ha, they emphasise that the average commercial farm in the UK produces around 8t/ha and this has been static for the past two decades.

Given the climatic variables that affect growth, winter wheat yield potential in different parts of the British Isles as shown in Figure 1.

This shows that most of the island of Ireland is in the 21t/ha yield potential bracket and yet we feel satisfied if we produce about half this amount.

Given this potential, it is hardly surprising that Irish growers have fared well in the YEN project to date and last year was no exception.

Second-highest yield

With a field yield of 15.68t/ha (6.345t/ac), Ian Howard from Bellewstown, Co Meath, was awarded a silver medal for actual grain yield in 2015.

This yield level was shared with another grower, but this project is not about absolute yield. Indeed, the organisers put the Howard crop in fourth place in terms of the actual harvested yield relative to its estimated yield potential.

Using data provided by Met Éireann, the YEN organisers estimated that this crop delivered 74.6% of its potential grain yield. While the actual yield level is credible by any standards, the fact that it is reckoned to be only 74.6% of its potential stated a theoretical potential yield of 21.02t/ha (8.506t/ac).

This might seem like an incredible yield level, but it is completely in line with the level of yield potential indicated in Figure 1.

The crop which scored highest in 2016 had both the highest actual field yield at 16.5t/ha (6.677t/ac) and the highest deliverance of its potential yield at 81%. This data indicates a potential yield in that field of 20.37t/ha (8.24t/ac).

These numbers represent serious yield potential relative to what is being achieved in practice. They also serve to highlight the real potential that exists in our current genetics.

What is also interesting is that the calculated potential yield is higher in this Irish crop and it is well past the time for more growers here to begin to capitalise on this potential.

It must also be noted that potential yield is mainly calculated on climatic parameters. It is important to remember that soil parameters can have a significant impact on our ability to deliver potential yield, but they cannot be factored into these measurements.

The Howard crop

As well as the basics, Ian Howard pays a lot of attention to his soil. Fertility is important and this field was high in P and K (Index 4) and received no P and K during the growing year.

But the fields had been in receipt of organic manure – chicken litter and compost – prior to the rape, plus farmyard manure for many years before that and this had helped to build soil fertility and health.

The variety grown was Horatio, which had been sown on 17 September 2014 at 188kg/ha (12st/ac), following oilseed rape, and sown with a Claydon drill.

This was a high seed rate for that sowing date and the final report stated that this crop produced the highest total biomass yield, but it also suggested that this may have been excessive and that the density of the canopy may have acted to limit grain yield through limited light interception.

The crop had a high ear count, but the estimated crop harvest index was only 48% (the proportion of the total biomass converted into grain) compared with 58% in the highest-yielding crop.

Otherwise, crop husbandry was quite normal. This included IPU + DFF plus insecticide in the autumn, followed by growth regulator plus chlorothalonil at GS30/31 on 10 April. The crop received 202kg N/ha (162 units N/ac) as CAN+S; one-third in mid-March, one-third on 14 April and the final third on 7 May.

The first fungicide was applied on 23 April at GS32, which was Skyway and Orchid, but chlorothalonil had been applied at GS31 with the PGR. A mid-T1 was also applied last year due to the extended period between the T1 and T2 following the early timing of the T1 treatment.

The project involved some inconvenience. Sampling was required throughout the season and this was done by Seamus Shevlin of Deeside Agri. Seamus also monitored the crop through to harvest along with Billy O’Dea.

However, Ian commented: “The inconvenience is small relative to the honour of being recognised for the work done and the yield levels achieved.”

Need for additional work has meant that applicants only tend to get involved in conjunction with a merchant and/or a co-op or company.

As stated previously, Ian’s participation in the YEN competition was sponsored by BASF Ireland