Crop yields beyond 2012

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In 2012 ADAS, with other industry organisations, jointly initiated a Yield Enhancement Network or ‘YEN’ to try to kick-start an upward trend in UK grain yields. 2012 was a bad year for UK cereal producers with smaller yields than for twenty years.  An industry review was published into possible causes of long-term yield stagnation in both wheat and oilseed rape. However, ADAS had been suggesting for a while that yields of 20 t/ha should theoretically be possible. So the time seemed right to take action. 2012 was also the year of the London Olympics, a cheerful celebration of sporting excellence. So our idea was to have a competition, not just to identify the best yielding UK cereal crops, but to work out how these high yields were produced, so all participants could benefit. Twenty crops were entered in the first year with a best yield of 13.4 t/ha, then 35 crops in 2014 (best yield: 14.5 t/ha), then 59 in 2015 with the best yield of 16.5 t/ha, a new world record. Over 100 growers participated in 2016, but their best yield was only 12.8 t/ha.

Crop yields beyond 2012

Whilst some YEN entrants like the element of competition, most growers join the YEN to benchmark their crops against similar crops on other farms, and to learn about enhancing yields. Almost all YEN participants are sponsored, so it doesn’t cost anything to join in, other than a little effort. The benefits of this are: free analysis of soil health (including pH, OM, P, K, Mg and respiration) and grain nutrient status for the crop that they enter, a programme of technical discussions focussing on enhancing yields, a full personalised 10-page report analysing the performance of the crop that was entered, attendance at an annual awards meeting, several newsletters and a website (

One key aim of the YEN is that entrants should be encouraged and supported in trying out new ideas that might increase yields. However, testing risky or expensive new ideas on a whole field tends to be prohibitive so this year we have set up a new ‘YEN Yield Testing’ option. Interested members attended an ‘ideas lab’ in January 2017 and, having discussed a range of possible approaches, farms formed themselves into various groups each willing to test the same idea on a couple of adjacent tramlines running across their YEN-entered field. These tramlines will mostly be harvested by mapping combine harvesters and ADAS will analyse the yield maps (using their new yield-map-analysis service) to see how likely it is that the ‘new idea’ really did cause more grain to be harvested.

As well as ADAS, current sponsors of the Cereal YEN are Adama, AgSpace, Agrimetrics, AHDB Cereals & Oilseeds, BASF, Bayer, de Sangosse, Hutchinsons, Limagrain, Nabim, NIAB, NFU, NRM, Rothamsted Research, Syngenta, TradeCorp, and Yara – so YEN now has broad industry support. A new Oilseed YEN has also been initiated this year with further sponsors. All sponsoring organisations provide considerably more than just financial support. For example NRM undertakes chemical analysis, AgSpace provides satellite images of each field, AHDB organises the programme of networking meetings, often in association with their Monitor Farms, Nabim is running a grain quality competition (new in 2017), NIAB provides yield verification, and Agrimetrics is developing software to make it easier for members to share data and results.

The YEN is open for anyone to enter, even from across Europe, and a ‘level playing field’ is established by expressing each yield as ‘% of potential’, as well as ‘tonnes per hectare’, with awards (gold, silver & bronze) being made for both. Potential yields are estimated according to the amount of light energy and water that a site receives in the year – the map shows how these potential yields varied across the UK in 2016, assuming a medium soil. For each site, by measuring the total amount of biomass produced at harvest-time, it is possible to estimate the quantities of light energy and water that the crop was able to capture, and so we can deduce whether it was a shortfall in light-capture or water-capture that most constrained the crop’s yield. Hence it is possible to suggest whether future management should focus more on improving rooting or improving canopy function. Currently most UK cereal crops only achieve 50-60% of their site’s potential so there appears to be plenty of scope for improvement.

The most obvious feature of YEN crops that accounts for their very varied performance appears to be the amount of biomass that they generate. Largest grain yields generally arise from crops producing well over 20 t/ha of biomass. This has set YEN entrants thinking about how to maximise biomass growth – key issues are how variety choice, earliness of sowing and nutritional programmes influence both shoot populations in spring and the length of time that crop canopies survive through July and maybe into August. We suspect that deep rooting has a big part to play in this but, so far, no-one has dug big enough holes to know how deep crops’ roots have reached.

Now the main signs of what is causing the highest yields have been identified, the research organisations sponsoring the YEN (ADAS, NIAB, Rothamsted, etc.) are aiming to initiate projects to investigate. By working together with the YEN entrants the aim is to show where the highest yields are coming from, and how they can be reproduced more widely and often.

The main tasks required of YEN entrants (and their sponsors or other supporters) are to register themselves and their crop with basic information about their location and soil type at as soon as possible (and before 15th July), provide digital photos during the summer, use the YEN sample-pack to provide ADAS with samples of whole-crop and of grain at harvest, plus verified yield details (using a weigh-bridge), and then send a print-out of their agronomy records after harvest. If the YEN website doesn’t have an answer to any remaining questions, then further enquiries can be sent to

Clearly, as shown by 2016, it is unrealistic to expect grain yields to increase every year. But on the other hand, the consistent differences between different farms and husbandry systems show that management decisions strongly affect cereal yields. Also, there are plenty of new and interesting ideas to try. It is very rewarding to see the high level of belief and enthusiasm amongst YEN participants that there is plenty of scope for enhancing grain yields in the UK and elsewhere in Europe. Let’s hope 2017 is a blockbuster for both high yields and knowledge about high yields!

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