Potential yields and yield gaps in wheat: the bases of wheat yield progress

Potential yields and yield gaps in wheat: the bases of wheat yield progress

CSIRO PLANT INDUSTRY

Tony Fischer | Honorary Fellow, CSIRO Plant Industry, Canberra, Australia

Presentation at Borlaug Summit on Wheat for Food Security 25-27 March 2014, Ciudad Obregon, Mexico

• Methodology for understanding past yield progress • Some case studies • Global summary by cases and megaenvironments • Wheat yield prospects

World average wheat yield 1983-2012 known here as farm yield (FY)

Potential yields and yield gaps in wheat: the bases of wheat yield progress | Tony Fischer 2 |

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

1980 1990 2000 2010 2020 2030

Yie

ld (

t/h

a)

?

Source FAOSTAT 2014

Slope linear at 32 kg/ha/yr (not curvilinear nor exponential)

Predicted yield in 2012 is 3.1 t/ha

Slope relative to 2012 yield is 1.0% per annum Must disaggregate

Wheat Breeding in Mexico and Yield Increases


Source (1976) Journal of the Australian Institute of Agricultural Science 42, 139–148.

Irrigated Wheat Yield changes in the Yaqui Valley


Source SARH, SAGARPA, Fischer and Wall (1976), Bell et al (1995), Ahrens et al (2012); D.Flores pers. comm.

0

100

200

300

400

0.0

1 . 0

2.0

3.0

4.0

5.0

6.0

7 . 0

8.0

9.0

1950 1960 1970 1980 1990 2000 2010

N F

ert

. rat

e (

kg/h

a)

Gra

in Y

ield

(t/

ha)

Potential yield (PY), CIANO plots against year of release, 1970s best agronomy

N rate on farm

Average Farm Yield

(FY)

slope 266 kg/ha/yr 6.0% of 1975 FY

Yield change in Yaqui Valley 1982–2012


Source SARH, SAGARPA; D.Flores, K.D. Sayre and I Ortiz-Monasterio pers. comm.

0

100

200

300

400

0 . 0

1 . 0

2.0

3 . 0

4 . 0

5 . 0

6 . 0

7.0

8.0

9 . 0

10 . 0

1975 1980 1985 1990 1995 2000 2005 2010 2015 N f

ert

. Rat

e (

kgN

/ha)

Yie

ld (

t/h

a)

slope 60 ± 9 kg/ha/yr 0 . 9 % of 2012 FY

FY

vs

year

N Rate

FY 2012

6 . 4 t/ha

slope 28 ± 10 kg/ha/ yr 0 . 3 % of 2012 PY

PY vs

year of release

PY 2012

9 t/ha

Yield Gap

41 % of FY

Surveys and satellite imagery suggest currently no lack of N, but small constraints: • late planting • late watering • summer weeds

Summary of approach

• In essence the approach views FY as PY less Yield Gap :

FY = PY ‒ Yield Gap

with the yield gap unlikely to be < ~30% of FY (or FY unlikely to be > ~77% of PY); larger gaps have an exploitable component


• Also, FY progress is PY progress less Yield Gap change: rel. change in FY = rel. change in PY less rel. change in gap Note

• Gap and gap change determined by difference (gap = PY – FY)

• Relative progress in PY is measured against year of release under latest agronomy, and this

• is assumed to translate into the same relative progress in FY upon full adoption of the technologies measured in PY progress.

• As such PY progress contains any positive agronomy by variety interaction.

• PY progress measure must avoid bias from greater disease in older varieties and must have representative

natural resource base.

Division of world wheat lands into wheat megaenvironments (WMEs) for balanced sampling

WME Moisture Latitude Global wheat Area (%)

Examples

Spring wheat

1 Irrigated Low 17 Mexico, S Asia, Egypt

2 + 3 High rainfall Low 5 Wet N Africa, Brazil

4 Low-mod rain Low 15 Australia, wet N Africa

5 Irrigated Low, hot 2 Bangladesh, Sudan

6 Low-mod rain High 20 Canada, Siberia

Winter (including facultative) wheat

10 Irrigated Middle 6 North China Plain

11 High rainfall Middle 23 Eurasia, E USA

12 Low – mod rain Middle 11 Great Plains, Anatolia

Total 100

Potential yields and yield gaps in wheat | Tony Fischer 7 |

Wheat yield progress in India and in Punjab State 1992-2012 (irrigated low latitude)


0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

1990 1995 2000 2005 2010 2015

Gra

in y

ield

(t/

ha)

slope 24 kg/ha/yr* 0.4%

PY Punjab State

slope 30 kg/ha/yr*** 0.7%

FY Punjab State

Yield gap 56% of FY

• Punjab progress not unlike Yaqui Valley but all yields lower

• Yield gap larger than Yaqui Valley: many small constraints

Source FAOSTAT, Singh et al 2011, I. Sharma pers.comm.

Wheat Yield Progress in Western Australia (water limited hence PYw)


• Notable gap closing due to better agronomy:

- conservation tillage and herbicides = earlier sowing , more moisture

- more crop diversity

- more nitrogen

• Gap partly driven by risk aversion of farmers in dry rainfed areas

Source NVT, ABARES

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

1980 1985 1990 1995 2000 2005 2010 2015

Gra

in Y

ield

(t/

ha)

FY slope 18 kg/ha/yr**

1.0%

PYw


Yield gap 45% of FY

Wheat Yield progress in the United Kingdom (humid, winter wheat)


• Excellent PY data from HGCA

• Results confirmed McKay et al (2010) applying linear mixed model analysis to the data, showing that

• agronomic progress in PY appears exhausted.

• Also yield gap small and increasing

• More so in France where FY not increasing significantly despite PY breeding progress

Source HGCA, FAOSTAT

slope 34 kg/ha/yr** 0.4%


4.0

5.0

6.0

7.0

8.0

9.0

10.0

11.0

12.0

1990 1995 2000 2005 2010

Gra

in Y

ield

(t/

ha)

FY

PY

Yield Gap 34% of FY

Note yield axis offset.

Summary of case studies on Wheat Yield Progress


Region

(Wheat

MegaEnvironment)

Estimated farm or potential yield

(t/ha) and yield gap (%) in 2010

Rate of change

(% p.a.)d

FY PY Yield gap FYe PYe Yield gapf

Spring wheat regions (some examples)

Yaqui Valley, Mexico (WME1) 6.4 9.0 41 g0.9 0.3 −0.6

Punjab, India (WME1) 4.5 7.0 56 g0.7 0.4 −0.3

Western Australia b (WME4) 1.8 2.6 44 g1.0 0.5 −0.5

North Dakota,b USA (WME6) 2.5 4.0 60 1.0 0.7 −0.3

bRainfed cropping regions commonly experiencing water shortage so PYw was estimated eAll FY and PY slopes are statistically significant at P < 0.10 or better, except for the FY slope for northern France (P = 0.13) fCalculated as FY rate of change less PY rate of change

Source: Fischer et al (2014)

Winter wheat regions (some examples)

Shandong and Henan (WME10) 5.8 8.8 52 1.7 0.7 −1.0

United Kingdom (WME11) 8.0 10.7 34 0.4 0.6 +0.2

Kansas,b USA (WME12) 2.8 3.8 36 0.7 0.4 −0.3

Average all cases (n = 12) 4.43 hna 48 ± 4 0.83 0.61 ± 0.06 −0.23

After weighting for WME production (WME 1 =23%, WME 6 = 13%, WME 11 = 38%) World 3.0 4.5 50 1.0 0.6 –0.4

Wheat yield prospects (next 20 - 40 years): continued PY progress? 1

• Currently at about 0.6% p.a. comparatively low (cf. rice 0.8%, maize 1.1%, soybean 0.7%) but no sign of a PY limit being approached although progress becoming more difficult and more expensive

• New agronomy is part of PY progress but options for greater yield are limited, possibilities:

‒ Soil physical status (e.g. Controlled Traffic)

‒ Soil microbiology in general

‒ Water limited situations:

‒ plastic mulching

‒ better seasonal climate forecasts and weather insurance

‒ for intermediate latitudes, earlier sowing, possibly with head frost resistance

(new agronomy for greater resource use efficiency is however vital)


Wheat yield prospects: continued PY progress? 2

• But conventional breeding still makes steady yield progress , and new tools are continuing to be developed to help efficiency which is undoubtedly falling:

‒ Computing, biometry, mechanization, robotics = more yield trials

‒ Managed environments, remote sensing, targeting physiological traits

‒ Molecular markers, culminating in genomic selection (GS)

• And untapped wheat genetic resources remain a likely source of yield genes but difficult and hence expensive to access by prebreeders


Wheat yield prospects: continued PY progress? 3

• What about non-conventional breeding?

‒ Heterosis, becoming so important now in tropical rice, will likely be harnessed for a 10-15% yield jump, possibly helped by GM

‒ The private sector can and will likely play a greater role in wheat breeding

‒ Can genetic engineering (GM) help on potential yield? Direct impact on PY/PYw unlikely in 20 years at least, indirect via freeing breeding resources more likely.

• And can we improve on 0.6% PY progress? Even with the private sector becoming involved? Overall looks quite difficult to me.


Wheat yield prospects: closing the yield gaps? 1.

• Gaps are smaller in wheat (avg 50%) than in rice (e.g. avg 76%, often >100%) and especially maize (36% in USA, but 100% in China, Argentina and >200% in SSAfrica)

• Gap closing inevitably means intensification on all fronts (physical inputs and managerial) , but it is also the path to more sustainable wheat systems and more efficient use of inputs (water, nutrients, energy) per kg grain produced

• Gap closing is generally considered to involve activities to promote adoption of existing technologies, i.e. agricultural extension, but this can be facilitated by breeding and agronomic research


Wheat yield prospects: closing the yield gaps? 2.

• Breeding can help gap closing through: ‒ More robust varieties e.g. more suited to soil disorders and new conservation

agriculture systems and

‒ Especially better pest/disease resistance, and here genetic engineering will help.

• Agronomic research can also help gap closing, for example:

‒ More appropriate conservation agriculture techniques/machinery

‒ Easier ways to diagnose and avoid nutrient deficiencies and

‒ to reap the benefits of greater rotational diversity in wheat cropping systems.

• No wish to underrate the importance and complexity of extension, which has also been subject to extensive research, debate and ongoing reinvention (e.g. innovation platforms).

• But time doesn’t permit further discussion of extension except to say that, however it is structured, it remains vital and unfortunately resource intensive, and much neglected in developing countries.


Wheat yield prospects: closing the yield gaps? 3. • Also unfortunately, beyond R, D and E, other barriers to yield gap closing are especially evident in

developing countries:

‒ Farmer skill levels, farmer access to financial resources and strong land tenure, weak farmer empowerment

‒ Poor input supplies, infrastructure, markets, and the absence of the institutions

• Eliminating these barriers has a long way to go as we look at wheat across the world:

‒ Low level of R, D and E investment generally in developing countries (R & D intensity < 1%)

‒ Urban and elitist biases in national policies which continue the neglect of rural development

‒ Inefficient seed systems, and

‒ the on-going shrinkage of farm size in developing countries which only impedes modernization and perpetuates rural poverty.

• Norman Borlaug understood well the big picture in agricultural development, and right from his early days here in the Yaqui Valley, strove at all levels of government to eliminate these barriers by promoting small farmer friendly policies

• Overall however at least for wheat the days of rapid yield gap closing have past, and keeping up the average global rate of yield gap closing of say 0.4% will be difficult


Summary of wheat farm yield prospects globally

• Potential yield (new tools cancelled by diminishing biological returns) +0.6% , no change

• less Yield gap change ( note diminishing exploitable yield gap in W Europe, elsewhere) ‒(‒ 0.4%), at best

• plus Carbon dioxide rise (2ppm p.a. ) but cancelled by warming zero

• and likely gradual shift from irrigated to rainfed production yield negative? ---------------------

Net prospect for FY 1.0%, at best


Likely rate of change (linear %p.a. relative to 2010 FY)

Summary (continued)

• Most estimates suggest 1% p.a. yield growth is not enough to meet demand growth esp. in next 20 years

• Consequences: equilibrium modelling points to likely higher real wheat price relative to 2010, greater stress for poor wheat consumers, larger wheat area (more rainfed), greater trade in wheat.

• Result responsive to more R , D and E investment but elasticity

uncertain and maybe low (<0.2); also effectiveness of R D & E an issue, and other rural investments (e.g. roads, education) often necessary

• With attention to all of these, the world might scrape by on wheat, but prospect for more urban price-driven crises remains higher with wheat than with other staples


CSIRO Plant Industry Tony Fischer | Honorary Fellow

t +61 2 6246 5244 e [email protected] w www.csiro.au


Thank you for your attention, and I acknowledge all the researchers whose published data has helped put together this presentation.

Also if you want to know more, there are 70 pages in the Wheat chapter in our new book (Fischer, Byerlee and Edmeades 2014) and over 500 in the whole book! Come and visit the poster.

Wheat Yield changes in the Yaqui Valley

• Especially early in the Green Revolution, one important aspect of this technological progress was the positive variety x fertility (N) interaction, looking like this:


0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

0 75 150 225 300

Gra

in y

ield

(t/

ha)

Nitrogen fertilizer rate (kgN/ha)

1980s varieties

1950s varieties

1950s N level

1980s N level Effect of :

:

variety X N

variety

N

Source Ortiz-Monasterio et al (1997)

Wheat Yield changes in the Yaqui Valley

• Secondly, part of the early FY progress by Borlaug in the Yaqui valley came from new varieties with better stem and leaf rust resistance

• This is not PY progress, which must be measured without disease; however maintaining disease resistance is a major achievement (and on-going role) of wheat breeding

• Also in measuring PY progress in vintage trials, must be careful to avoid disease, which if present will tend to bias upwards the estimated rate of PY progress, as the following research here at CENEB showed:


Source Sayre et al (1998)

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

1965 1975 1985 1995

Gra

in y

ield

(t/

ha)

Year of Variety Release

With fungicide

No fungicide (=leaf rust)

slope 27 kg/ha/yr*** or 0.5%

slope 92 kg/ha/yr*** or 1.7%

CSIRO.

Yaqui Valley: now > 90% of wheat on raised beds.

Wheat yield progress in Kansas ( dry, winter wheat)


• Acreage loss to GM maize and soybean

• Conservation tillage has led to less summer fallows

• Tough environment including many biotic stresses

Source Nalley et al (2008), NASS (2012)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

1980 1985 1990 1995 2000 2005 2010

Gra

in y

ield

(t/

ha)

Year

PYw

FY

slope 20 kg/ha/yr*

0.7%

slope 14 kg/ha/yr***

0.4%

Yield Gap 36% of FY

0.0

0.5

1.0

1.5

2.0

2.5

1850 1870 1890 1910 1930 1950 1970 1990 2010

Gra

in Y

ield

(t/

ha

) Change in average farm yield (FY) of rainfed wheat in Australia over the period 1852−2012 showing major drivers of change (curves

hand fitted)


Source Adapted from Donald (1964), Fischer (2009) and J.F.Angus and J.Kirkegaard pers. comm. 2011

Exploitative farming

Fallowing, P fertilizer, adapted vars.

Mechanization, legume pastures, herbicides

Semidwarf vars., break crops, N fertilizer

Millennium drought

Farm yield (FY) wheat in WANA

Country

Average 2010-2012 Increase 1993-2012 %p.a., rel. 2010-12

Comments Prodn Mt

Area Mha

Yield t/ha

Prodn Area Yield

Turkey 20.52 7.91 2.60 (0.3) -1.3 1.3 FY takeoff 2009?

Iran 13.21 6.80 1.94 1.5 (0.2) 1.3

Syria 3.52 1.57 2.24 (-0.1) (0.0) (-0.2)

Iraq 2.65 1.34 1.98 3.1 (-1.5) 3.8

S. Arabia 1.21 0.20 5.93 (-3.4) -7.5 1.7

Kazakhstan 14.07 13.10 1.06 2.8 1.1 2.0

Uzbekistan 6.59 1.40 4.71 4.6 1.4 4.2

Afghanistan 4.32 2.37 1.82 3.3 1.2 2.6

Morocco 4.92 3.03 1.63 2.3 0.8 (2.1) FY slope P=0.103

Algeria 2.86 1.79 2.69 3.1 (1.1) 2.7

Tunisia 1.32 0.65 2.00 (1.6) (-0.9) 2.2

Egypt 8.13 1.30 6.23 2.4 1.7 1.0 FY plateau >2003

Ethiopia 3.07 1.54 1.99 4.3 3.4 2.1

Sudan 0.34 0.20 1.71 (0.4) (-1.6) (1.6) Source FAOSTAT Mar 2014

Wheat yield progress in India and in Punjab State 1992-2012 (irrigated low latitude)


0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

1990 1995 2000 2005 2010 2015

Gra

in y

ield

(t/

ha)

slope 24 kg/ha/yr* 0.4%

PY Punjab State


FY Punjab State

FY India slope 29 kg/ha/yr***

1.0%

Yield gap 56% of FY

• India yield not stagnant

• Punjab progress not unlike Yaqui Valley but all yields lower

• Yield gap larger than Yaqui Valley: many constraints

Source FAOSTAT, Singh et al 2011, I. Sharma pers.comm.

Summary of case studies on Wheat Yield Progress


Wheat

mega-

environment

Region

Estimated farm or potential yield (t/ha)

and yield gap (%)

Rate of change

(% p.a.)d

FY PY Yield gap FYe PYe Yield gapf

Spring wheat regions

1 Yaqui Valley, Mexico 6.4 9.0 41 g0.9 0.3 −0.6

1 Punjab, India 4.5 7.0 56 g0.7 0.4 −0.3

1 Jiangsu, China 4.6 7.5 63 0.8 0.7 −0.1

4 Western Australiab 1.8 2.6 44 g1.0 0.5 −0.5

6 Saskatchewan,b Canada 2.3 3.8 69 0.8 0.6 −0.2

6 Saskatchewan,b,c Canada 2.2 3.6 64 0.7 0.5 −0.2

6 North Dakota,b USA 2.5 4.0 60 1.0 0.7 −0.3

6 Finland 3.7 4.8 30 1.0 0.8 −0.2

Winter wheat regions

10 Shandong and Henan, CN 5.8 8.8 52 1.7 0.7 −1.0

11 United Kingdom 8.0 10.7 34 0.4 0.6 +0.2

11 Northern France 8.6 10.8 26 0.3 1.1 +0.8

12 Kansas,b USA 2.8 3.8 36 0.7 0.4 −0.3

Overall average

Average (n = 12) 4.43 hna 48 0.83 0.61 −0.23

bRainfed cropping regions commonly experiencing water shortage so PYw was estimated cDurum wheat dAll rates of FY progress and gap closing contains the direct effect of CO2 rise (~0.2% p.a.) eAll FY and PY slopes are statistically significant at P < 0.10 or better, except for the FY slope for northern France (P = 0.13) fCalculated as FY rate of change less PY rate of change gFY rates of change include small but significant weather trends (see text) for which no correction is applied here; two were unfavourable and one favourable for FY

Source: Fischer et al (2014)

Wheat

Mega-environment

Weighting factor

(fraction of total)

Estimated values for

2008–10

Estimated rate of change relative

to 2008–10 values

(% p.a.)

Area Producti

on

PY

(t/ha)

Gap

(%)

FY

(t/ha) PY Gap FY

Spring wheat regions

1,2,3 = irrig., humid, low lat. 0.23 0.23 5.5 83 3.0 0.6 −0.4 1.0

4,5 = dry and hot, low lat 0.17 0.08 2.5 67 1.5 0.3 −0.9 1.2

6 = High lat. 0.20 0.13 3.0 50 2.0 1.0 −0.2 1.2

Winter (and facultative) wheat regions

10 = irrigated, middle lat 0.06 0.09 6.5 44 4.5 0.5 −1.1 1.6

11 = humid middle lat. 0.23 0.38 6.5 30 5.0 0.7 0.0 0.7

12 = dry, middle lat. 0.11 0.09 3.0 30 2.3 0.5 −0.3 0.8

After weighted average

World average 1.00 1.00 a4.5 b50 a3.0 b0.6 b−0.4 b1.0

Key wheat yield statistics by world wheat megaenvironments.

aWeighted by area of WME bWeighted by production of WME Source:.

Source: Fischer et al (2014). Estimates apply to 2008–10 when average world wheat area

was 222 Mha and production was 674 Mt

Presentation title | Presenter name 32 |

Potential yields and yield gaps in wheat: the bases of wheat yield progress

Science

Transcript of Potential yields and yield gaps in wheat: the bases of wheat yield progress