TEMA: KORN OG BÆLGSÆD
20 The world´s highest yields
Improving wheat yields in high input
agriculture
Wheat yields have stagnated for ~20 years in many countries. A new Yield Enhancement Network
is now seeking to rejuvenate advances in cereal yields.
Professor, Head of Crop Performance Roger Sylvester-Bradley
ADAS Boxworth, UK
[email protected] or www.yen.adas.co.uk
Yield ‘plateaux’ in Denmark
(Petersen et al., 2010), France
(Brisson et al., 2010) and the
UK (Knight et al., 2012) have
been attributed to changing climates, deteriorating soil conditions and sub-optimal crop nutrition. Underlying causes are
identified as (i) decoupling of
public support for agriculture,
low commodity prices and inflated land values (and rents)
which divert the focus of farming innovations towards costcutting, and (ii) the retreat of
biological science from the field
to the laboratory.
Philosophy & Approach
Our estimates of the bio-physical yield potentials of cereal
crops where high inputs are possible (such as the UK) indicate
ample scope for further yield enhancement (Figure 1). However, realisation of these potentials
will depend on creating conditions for innovation which involve leading farmers and their
support industries, as well as
scientists, and which re-focuses
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farmers’ attention on enhancing
capture and conversion of the finite resources for crop growth:
light energy and water, rather than merely on variety and
chemical comparisons.
A Yield Enhancement Network (YEN) has therefore been
initiated in the UK and Ireland
with the specific aims of identifying and supporting on-farm
innovation for crop yield enhancement. The YEN supports
farmers in competing for the
highest yield and the greatest
proportion of potential yield. It
employs not only verified measurements of yield but also measurements of how farmers’ crops
capture and convert resources
for growth.
Results
The greatest cereal yield measured by YEN members in 2013
and 2014 was 14.50 t/ha; this represented 76% of the estimated
bio-physical potential of the
land where the crop was grown
(in east Lincolnshire, 2013-14).
Figure 1. Estimated potential cereal yields for soils holding 210 mm available water (a) with
average solar radiation and summer rainfall, and (b) with radiation and summer rainfall in
2013. Locations of YEN competition contestants in 2013 are also indicated.
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TEMA: KORN OG BÆLGSÆD
The world´s highest yields
Figure 2. Two eras of UK wheat breeding: increasing harvest index
before 1990; increasing biomass after 1990 (Clarke et al., 2012).
The most obvious feature of this
record crop was its large production of biomass: 22.9 t/ha. Indeed the obvious explanation
of the yields achieved by YEN
crops was their close dependence on total shoot biomass.
Discussion
Comparisons of UK wheat varieties over the last 50 years show
that genetic yield enhancement
took place by increasing harvest
index until about 1990, but by
increasing total shoot biomass
after 1990 (Figure 2), possibly with prolonged crop development (Clarke et al., 2012).
Whilst some of this extra biomass may have been achieved
by improved efficiency, genetic
potential of modern wheat varieties can clearly be enhanced
through capturing more resources for growth. Recent data indicate that average wheat
root density is less than 1 cm2
at ~0.4 m depth, hence modern
Figure 3. Root densities of 3 crops sampled in the 1970s and 1980s
and 17 modern crops (green) (White et al., 2014).
crops may be unable to capture
adequate water for enhanced
biomass growth.
We invite growers and their
sponsors from Denmark (and
further afield) to join the YEN,
and to thereby generate a European network of on-farm innovators, focussed on enhancing
crop growth and productivity,
and supported by comprehensive crop analysis and improved
understanding.
References
Brisson N, Gate P, Gouache
D, Charmet G, Oury F-X
& Huard F. 2010. Why are
wheat yields stagnating in
Europe? A comprehensive
data analysis for France.
Field Crops Research 119:
201–212.
Clarke S, Sylvester-Bradley R,
Foulkes J, Ginsburg D, Gaju
O, Werner P, Jack P, Flatman
E & Smith-Reeve L. 2012.
Adapting wheat to global
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warming or ‘ERYCC’ – Earliness and Resilience for
Yield in a Changing Climate.
HGCA Report No. 496, p.
131.
Knight S, Kightley S, Bingham I, Hoad S, Lang B, Philpott H, Stobart R, Thomas
J, Barnes A & Ball B. 2012.
Desk study to evaluate contributory causes of the current ‘yield plateau’ in wheat
and oilseed rape. Project Report No. 502, p. 225.
Petersen J, Haastrup M, Knudsen L & Olesen JE. 2010.
Causes of yield stagnation
in winter wheat in Denmark.
DJF Report Plant Science
No. 147, p. 149.
White C, Berry P & Sylvester-Bradley R. 2014. More
rooting, more food, less water? Abstract C7.73 presented at SEB meeting on Roots
for Global Food Security,
Manchester.
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