Addressing shortcomings in current agronomic practice is one of the first steps needed to tackle the UK’s yield plateau in winter wheat and oilseed rape, according to an HGCA study published today.
The Yield Plateau report was commissioned by HGCA and Defra in 2011 to look at the factors limiting increased yields in the UK and to address gaps in current industry research.
The study, led by NIAB TAG in conjunction with SRUC and Cambridge University, is the first to take an independent and comprehensive overview of the issues and involved the analysis of data going back to the 1940s.
The report looked at climate and weather patterns, plant breeding, economic influences, farm management practice and the impact of commodity prices on yields.
Since the 1990s, UK winter wheat yields have stalled while oilseed rape yields have fluctuated wildly over the past 30 years noted Stuart Knight, NIAB TAG’s Director of Crops & Agronomy and lead author of the report. This is despite genetic yield gain continuing to deliver potential progress at more than 0.5% per year for winter wheat and 2% for oilseed rape.
The aims of this study were to identify agronomic factors that may be constraining wheat or oilseed rape yield improvement, assess the scope and opportunities for raising national yields through agronomy and highlight knowledge gaps or barriers to be addressed.
National yield trends were analysed in relation to cropped area, genetic improvement, weather patterns, economic influences, crop nutrition and protection, plus other aspects of agronomy.
In contrast, yield in oilseed rape responds positively to increasing sunshine hours and negatively to increasing rainfall in spring, likely resulting from enhanced pollination and increased crop photosynthesis giving improved seed-set. Recent warm dry springs, combined with cold dry winters, which reduce some pests and diseases, are implicated in improved oilseed rape yields in the last few years.
Pests, weeds and disease
While pest and disease management remains a challenge, there is little indication of rising pest or disease incidence since the mid-1990s. Both winter wheat and oilseed rape have seen increasing trends in fungicide use as crop prices have recovered from lows in the 1990s and early 2000s.
The incidence of some nematode species may be increasing but the implications of this for yield are uncertain. Yield impacts of emerging diseases such as verticillium wilt and clubroot in oilseed rape are also unknown as is the effect of Turnip Yellows Virus (TuYV), although there is no evidence of a trend in the annual occurrence of aphids causing TuYV.
Weed management has become increasingly difficult in many key wheat producing areas, with control of black-grass particularly challenging for some farmers. The direct impact on yield may have been minimal but, on some farms, overall crop management strategies are now heavily influenced by the need to maximise black-grass control, which may restrict options for increasing yield.
'No simple solution'
Dr Susannah Bolton, HGCA’s Head of Research and Knowledge Transfer, said the report gave more clarity to a complex subject and provided an important reference point for the industry to start moving forward.
She said: “This report clearly shows there is no simple solution to the problem of stagnating yields. The study suggests getting the most from yield potential will require changes to agronomic practice and improved variety selection in the short-term, while issues such as a better understanding of soil health and improved collection of on-farm yield data need to be addressed in the future.
“HGCA is already addressing some of the points raised, particularly around providing more regional data in the Recommended Lists and investing in soils research.
“Next year, HGCA will be preparing to consult on its research strategy for 2014 onwards and this report will play an important part in helping inform our priorities for levy payer investment.”
Data from Defra’s Farm Business Survey has shown the yield gap between the top and bottom quartiles of growers has increased from 3 tonnes per hectare in the late 1980s to 4.5 tonnes per hectare in 2009. Growers in the top 25% have also performed better financially. The report suggests this is consistent with more effective farm management, which has improved knowledge transfer at its heart.
The Yield Plateau report makes a series of specific recommendations for the industry. These include short-term opportunities to help growers get the most from current operations, medium-term changes in industry approach and longer-term aims to prepare for the future. These include:
Short-term:
· Building on the HGCA Recommended Lists system with additional information for varieties in specific situations
· Better tools to manage and monitor crop growth and lodging risk – addressing the reasons why some growers may not favour higher-yielding varieties
· More proactive responses by industry to the problems of pesticide resistance and improving grower tools to manage and mitigate risks
Medium-term:
· Industry research on how agronomy can impact on and improve N efficiency, including interactions with soil management and rooting
· Ensuring precision farming techniques are more practical and accessible for small or medium-sized farms
· An updated analysis of areas where crops are at medium or high risk of sulphur deficiency and likely to respond favourably to sulphur applications
· Plugging the knowledge gap on the state and health of UK soils, particularly the incidence of compaction and variations in soil organic matter
Longer-term:
· Improved collection of data on farm practice to better monitor changes in practice
· Breeding and selection of varieties better suited to changing environmental conditions in the UK
To date, HGCA has commissioned 30 research projects under its three year ‘Investing in Innovation’ research strategy for 2011 to 2014.
This includes £1.6 million of levy payer investment in three soils projects, and a further £300,000 in weeds research this year. Total research investment to date is £8.1 million, including £4.4 million of HGCA levy funding.
