1.
Can ecological practices mitigate
floods and droughts?
Pairing meta-analysis with a hydrology model to
understand soil water impacts
Andrea Basche
Research Fellow
SWCS Annual Meeting
July 31, 2017

2.
UCS Happy Hour & Upcoming Report
• 5:30pm-7:30pm
TONIGHT! at The
Great Dane
• Learn more about
upcoming floods and
droughts report AND
how to stay
connected to our
Science Network
resources

3.
Scattered Trees
Forest
Prairie
Water/Wetland
Historic Vegetation of Iowa
1832-1859
Source: Iowa State University
Iowa Dept. of Natural Resources
Basche and Edelson. 2017. Agroecology and Sustainable Food Systems.

4.
Basche and Edelson. 2017. Agroecology and Sustainable Food Systems.

5.
45%
7%
Basche and Edelson. 2017. Agroecology and Sustainable Food Systems.

6.
Healthy soils could lead to better
water outcomes, yet questions remain
• What do soil improvements actually mean for
water impacts on a field scale?
• What practices are most effective and in what
environments?
• How do conservation practices change water
outcomes on a landscape scale?

7.
No-TillCropland
Grazing
Cover
Crops
Perennials
Perennial
grasses,
Agroforestry,
Forestry
Crop
Rotation
Grazing
Management
Reduced rates,
Rotational grazing,
Grazing exclusion
Meta-analysis
How do agricultural practices
in crop & grazing lands impact
infiltration rates on individual fields?
7 studies 52 studies 11 studies 23 studies 37 studies 8 studies
24 205 39 81 221 40
Number of paired observations
Basche and DeLonge. Under Review; DeLonge and Basche. Under Review.

8.
No-TillCropland
Grazing
Cover
Crops
PerennialsCrop
Rotation
Grazing
Management
Meta-analysis
7 studies 52 studies 11 studies 23 studies 37 studies 8 studies
TREATMENT
Conventional
or Reduced
Tillage
Crops
Only
No
cover
crop
Annual
Crop
System
Mono-
culture
Conventional
or Continuous
Grazing
CONTROL
How do agricultural practices
in crop & grazing lands impact
infiltration rates on individual fields?

9.
No-TillCropland
Grazing
Cover
Crops
PerennialsCrop
Rotation
Grazing
Management
Meta-analysis
Average infiltration rate improvement
-21% +6% +19% +35% +59% +59%
7 studies 52 studies 11 studies 23 studies 37 studies 8 studies
Basche and DeLonge. Under Review; DeLonge and Basche. Under Review.

10.
How do continuous living cover practices impact
water storage on individual fields?
Porosity
Upper end of
plant available
water
Mean increase of 8-9%
for 27 studies analyzed
Only evaluated
continuous living cover
practices: cover crops,
perennial crops and
agroforestry
Basche and DeLonge. In Press. Soil Science Society of America Journal.

11.
Diverse cover crops
Perennial crops (i.e. alfalfa)
Livestock on perennial grassesHow do agricultural practices
in crop & grazing lands impact
water on a landscape scale?

12.
Livestock on perennial grasses
Improving water outcomes
with better soil water
storage capacity and more
diverse crop management
Diverse cover crops
Perennial crops (i.e. alfalfa)

13.
Livestock on perennial grasses
Basin Characterization
Model
Diverse cover crops
Perennial crops (i.e. alfalfa)

14.
Perennial grasses in
areas with
>5 tons/acre/yr
soil loss
Cover crop added
to areas with
>2 tons/acre/year
soil loss
Daily Erosion Project Modeling, Iowa State University. Cruse et al. 2006. Daily estimates of rainfall, water runoff, and soil erosion in
Iowa. Journal of Soil and Water Conservation..

15.
Perennial grasses in
areas with
~$80 ha/yr loss
Cover crop added
to areas with
<$50 ha/yr profit
Brandes et. al. 2016. Subfield profitability analysis reveals an economic case for cropland diversification. Environmental Research Letters.

16.
Livestock on perennial grasses
Diverse cover crops
Perennial crops (i.e. alfalfa)
• 10-14% less runoff overall
• 7-10% more water use
from plants overall
• In severe droughts (1988,
2012) up to 16% greater
crop water use
• Similar magnitude
benefits with future
climate

17.
Cedar Rapids
• 22% perennials
• 27% including
cover crop
• 17% reduction
in flood
frequency
• 13% less runoff
• 8% more crop
water use
X% of Least Profitable
Corn/Soy Acreage
Shifted to:
Creates Benefits of:

18.
Profitability Scenario: Runoff Reduction

19.
Erosion Scenario:
Actual Evapotranspiration

20.
Summary
• Conservation practices have clear benefits for
water infiltration and water storage on field
and landscape scales
• Largest benefits come from continuous living
cover
• Targeting regions of lower profitability or
greater erosion potential to include perennials
or cover crops to build healthier soil improves
water use efficiency in wetter and drier years

21.
UCS Happy Hour & Upcoming Report
• 5:30pm-7:30pm
TONIGHT! at The
Great Dane
• Learn more about
upcoming floods and
droughts report AND
how to stay
connected to our
Science Network
resources

22.
Thank You

23.
Analysis Details
• For each study, extract key data:
– Infiltration rate with & without conservation practices
– # treatment replications
– location
– annual rainfall
– soil type
• Calculate “Response Ratio”
– Ratio of infiltration rate of experimental treatment / the control treatment
• Statistics
– mixed-effect models
– take into account effect of study
Basche and DeLonge. Under Review; DeLonge and Basche. Under Review.

24.
No-TillCropland
Grazing
Cover
Crops
PerennialsCrop
Rotation
Grazing
Management
Meta-analysis
7 studies 52 studies 11 studies 23 studies 37 studies 8 studies
Infiltration rate improvements greater than
one inch/hour (conservation – control)
21% 31% 22% 37% 42% 53%
Percent of experiments that showed this large improvement:

25.
Wang et al. 2015
Wang et al. 2015
LRR > 1
3-5x IR
increase
Perennial Experiments

26.
Basche and DeLonge. Under Review; DeLonge and Basche. Under Review.

27.
Brandes et. al 2016 Subfield profitability analysis reveals an economic case for cropland diversification. Environmental Research Letters

28.
Percent [%] increase in Infiltration Rate
(with Conservation Practice)
No-Till
Grazing Exclusion
Grazing Management
Cover Crop
Perennials
Crop Rotation
Crop & Livestock
NO CHANGE
# observations

29.
How do continuous living cover practices impact
water storage on individual fields?

30.
How do continuous living cover practices impact
water storage on individual fields?

31.
Erosion Scenario: Runoff Reduction

32.
Profitability Scenario:
Actual Evapotranspiration

33.
No-Till Experiments

34.
No-Till Experiments

35.
No-Till Experiments

36.
No-Till Experiments

37.
Cover Crop Experiments