Can flexibility be built into cropping systems for adapting to climate uncertainty?(practical, on ground, farming systems)

Presenter: Darshan Sharma Centre for Cropping Systems

Northam, WA

This project DAW00202 'Demonstrating adaptation to climate change in the wheatbelt of Western Australia through innovative on-farm and virtual farm approaches' is funded by the Department of Agriculture and Food, Western Australia, the Grains Research and Development Corporation and the Australian Government's Climate Change Research Program.

WA DAFWA Team: Caroline Peek, Glen Riethmuller, David Bowran, Doug Abrecht, Geraldine Pasqual, Meredith Fairbanks, David Gray,

Leon C. Megginson (1963) (Professor of Management and Marketing at Louisiana State University at Baton Rouge)

‘According to Darwin’s Origin of Species, it is not the most intellectual of the species that survives; it is not the strongest that survives; but the species that survives is the one that

is able best to adapt and adjust to the changing environment in which it finds itself.’

- implies flexibility would win under variable env

- but opens the challenge:how can cropping systems be adjusted to changing climate?

Background

Background

ChallengeHow to adapt farming system to ± ?

We agreeClimate is changing/changed

In most of the Southwest of WATemperature: ± Rainfall : ↓ ±

Source: IOCI

Hypothesis

Hypothesis

Flexibility in cropping systems by:1. Growing a variety that exhibits desirable

plasticity/stability of yield components

2. Strategically structured plant populations to maximise crop buffering

3. Population control where farmers could kill a part of the crop under water deficient conditions

Rationale

1. Plasticity/StabilityWheat Grain yield =

Number of grains/spike X Mean Grain weight X Number of spikes/area

Some varieties are more plastic for some traits than others.

Spike size change : Grain weight change

e.g. Eagle Rock is more stable for Grain weight while Carnamah is more plastic for Grain weight

2. Population structure

• Mix the seed of different varieties to build buffering capacity

• Varietal blends have been used to buffer disease resistance

• Wheat blends may also offer a small yield advantage even in the absence of severe stress…. Gallandt et al (2001); Cowger and Weisz (2008)

• We think, carefully devised varietal mixtures can be used to stabilise yield against seasonal uncertainty- such as frost, end of season drought, good spring rains

for example- Population structure• Say,

– 4t/ha anthesis Biomass ~ 2.4t/ha gy potential– 20mm post-frost R/F ~ 3 additional filling days– 4% grain fill/day

• Additional grain Mixture ~ 3 times

Additional grain from 20 mm late rain(theoretical)

0

50

100

150

200

250

300

350

0 20 40 60 80 100

% yield lost due to frost on early flowering variety

Ad

dit

on

al

Gra

in (

kg

/ha

)

One variety (earlyflowering)

Two variety mix(one varietyunaffectged)

3. Population control

High plant density may reduce grain yield in rapidly warming and drying conditions.

Mullewa 2001

1.01.01.11.11.21.21.31.3

0 100 200 300

Plant density (plant/m2)

Gra

in y

ield

(t/

ha

)

BUT there are reasons to start with high plant density• Optimum plant density- changes with season• High plant density- good for weed control• High seed rate- good for uncertain crop establishment• High plant density- good for early wind erosion• High plant density- good for wider rows (what works for crop, also works for weeds)

• As such, Growers would often wish if some plants could be sacrificed LATER in the season according to latest weather forecast for remainder of the season!

We think, Shandying herbicide tolerant and intolerant varieties- a possible option to create an EXTRA decision point that MAY be used LATER in the season

Photograph by: Harmohinder Dhammu

Tolerant + Intolerant + Spray = Half the population

Conclusion

Conclusions• Flexibility of cropping systems for adapting to climate

uncertainty seems achievable.

• Some technologies for adapting to climate change are already there but need objective testing within the emerging farming systems.