CONSERVATION PRACTICES TO INCREASE RESILIENCY

Making sure we can handle the extremes!

Carolyn Olson, Ph.D.90th Annual Outlook Forum February 20-21, 2014

SOIL MANAGEMENT AND SOIL HEALTH

FACTORS AFFECTING RESILIENCY

Inherent Soil Properties texture

mineral content

Dynamic Properties Water Holding Capacity

Organic Matter Content

Soil Moisture

Soil Temperature

Images Courtesy Purdue University

July 2012

September 2012

GOOD SOILS = GOOD YIELDS

Mean NCCPI

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Co

un

ty Yield

(g m

-2)

180

200

220

240

260

280

300

320

340

KentuckyIowaNebraska

Kentucky(Double crop)Y = 131.187 + 187.458X. r2 = 0.72***

Soybean yields across Iowa, Kentucky, and Nebraska

SOIL WATER BALANCE

Soil Water

Precipitation

irrigation

Evapotranspiration (ET)

Runoff

Drainage

= -

Inputs Losses

Corn Water Use 2000

Day of Year

100 120 140 160 180 200 220 240 260 280

Wate

r U

se (

mm

)

0

100

200

300

400

500

600

Clarion Spring N (100 kg/ha) Webster Spring N (100 kg/ha)Clarion Fall N (200 kg/ha)Webster Fall N (200 kg/ha)

Organic Matter (%)

0 1 2 3 4 5 6 7

Ava

ilab

le W

ate

r C

onte

nt

(%)

0

5

10

15

20

25

30

35

Data Points Sand, AWC = 3.8 + 2.2 OMSilt Loam, AWC = 9.2 + 3.7 OMSilty clay loam, AWC = 6.3 + 2.8 OM

WATER IS REQUIRED FOR GRAIN PRODUCTION

Corn Water Use Efficiency

Water Use (mm)

200 300 400 500 600 700 800 900

Yie

ld (

kg h

a-1)

8000

10000

12000

14000

16000

18000

20000

22000

24000

26000

28000

Water deficitneed 5 inches more water to grow 300 bu corn

EVAPOTRANSPIRATION

ET = Soil water evaporation + Plant transpiration

Energy Input

(Net radiation)

Water Vapor

Gradientf (temp, vapor

pressure)

Windspeed

Gradient

Soil Water Availabilit

y

Components of ET

Potential ET (how much could evaporate) vs Actual ET (how much does)

Rate-limitation

PROJECTED CHANGE IN NORTH AMERICAN PRECIPITATION

BY 2080-2090

PRECIPITATION CHANGES

Change in seasonality Change in intensity Change in frequency Change in regional distribution

IMPLICATIONS

Soil water availability will become more variable because the input will be more variable

How do we manage soil water when the supply has an increased variation

Wet SpringHot Summer

Wet SpringCool Summer

Dry SpringCool Summer

Dry SpringHot Summer

CLIMATE PROJECTION:WETTER SPRING, HOTTER SUMMER

Iowa climate projection is average May-June rainfall and July-August temperature using 9 downscaled climate scenarios, spanning 3 GCMs and 3 emissions scenarios.

Training period for downscale method is 1960-1999.

Data Source: Stoner et al. (2013)

CLIMATE PROJECTION:FEWER WET SUMMERS, MORE HOT SUMMERS

Iowa climate projection is average May-June rainfall and July-August temperature using 9 downscaled climate scenarios, spanning 3 GCMs and 3 emissions scenarios.

Training period for downscale method is 1960-1999.

Data Source: Stoner et al. (2013)

TEMPERATURE CHANGES

Warmer temperatures increase ET demand through vapor pressure deficit

Warmer temperatures will increase the rate of water use inducing agricultural drought more quickly

OBSERVATIONS

Tillage increases the soil water evaporation rate

Yield differences among soils within a field is related to organic matter content and soil water holding capacity

Water use patterns within a field cause “drought” stress to occur in every year

Organic Matter (%)

0 1 2 3 4 5 6 7

Ava

ilab

le W

ate

r C

on

ten

t (%

)

0

5

10

15

20

25

30

35

Data Points Sand, AWC = 3.8 + 2.2 OMSilt Loam, AWC = 9.2 + 3.7 OMSilty clay loam, AWC = 6.3 + 2.8 OM

BENEFITS OF CONSERVATION AGRICULTURE

Short-term Reduce soil water

evaporation Increase infiltration

of rainfall or irrigation events

Reduce the overall of evapotranspiration rate if plants are grown in standing stubble

Long-term Increase the soil

water holding capacity through improved organic matter content

Increase water availability to the crop

Increase rooting depth

RESILIENCY STRATEGIES

Conservation practices focused on dynamic soil properties such as improving soil organic matter and water holding capacity - broadly, soil health Conservation tillage Cover Crops Residue

Management

No Till

Conventional

CONSERVATION PRACTICES Can’t make it rain any more often and at the

optimum time to have best yield Will increase the ability of the soil to capture

more water, reduce the evaporation rate from the soil surface, and increase water availability to the crop

Over the long-term will increase the capacity of the soil to store more water and make water available to the plant

Will increase the overall resiliency of the cropping system to withstand climate stresses (variable precipitation and temperature extremes)