The Water Cycle:
Impacts of Annual/Perennial Bioenergy Crops
Eleanor Burkett - Extension Educator, University of Minnesota
Roberta Dow, PhD - Extension Educator, Michigan State University
Course outline
 Overview of the water and water cycle
 Demands for water
Water quantity & bio mass production
Water quality & bio mass production
 Other considerations
Evaporation
Runoff
OCEANS
Earth’s Water
Budget
ATMOSPHERE
<.001%
97.5%
2.4%
LAND
Water Cycle
The Water Cycle
Water Quantity
Crop water needs are determined by
considering crop, soil type and region as
well as climatic conditions
CLIMATIC
CONDITION
Julie Doll
CROP WATER NEEDS
LOW
HIGH
Sunlight
Cloudy
Sunny
Humidity
Low
High
Temperature
Low
High
Wind
Calm
windy
Water Quality
Evaporation Considerations
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Air pressure
Temperature of the air
Temperature of the water at the air-water or air-soil surface
Air humidity
Area of the air-water surface (larger area, greater
evaporation)
 Depth of water affects water currents moving heat and the
ability to keep the surface temperature at evaporation level
 Airflow at the water or soil/air surface
 Shallow water table and bare soil for soil-water evaporation
Evaporation Influences
 Plant canopy over soil – impacts soil
temperature
 Mulch or leaf litter –impacts water
temperature, and air flow
 Amount of water in soil—impacts
temperature
 Soil texture
http://techalive.mtu.edu/meec/module01/images/Evaporation.jpg
Infiltration & Runoff Influences
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Slope
Soil type—permeability
Impermeable surfaces in developed areas
Soil surface cover—Plants and mulch or other organic
matter on surface
 Soil moisture channels –Worm holes, animal burrows,
root channels all increase infiltration
 Cultivation & management techniques such as contour
farming, terracing, grassed filter strips, etc.
http://upload.wikimedia.org/wikipedia/commons/9/95/Runoff_of_soil_%26_fertilizer.jpg
Runoff Control
Slope
Management
Runoff
Management
Diversion channels
Terraces
Contouring
Engineered structures
Vegetative barriers
Water reservoirs
Check dams
Grassed waterways
Soil
Management
Crop
Management
Conservation tillage
Mulching
Contour farming
Breaking up hardpan
Cover crops
Vegetative barriers
Strip cropping
Inter-cropping
Crop selection related to
the water cycle
 Seasonal differences: frozen vs. non-frozen
 Soil cover—NRCS Runoff Control Numbers for
various covers
Bare vs covered
Forested vs annual
Grasses vs annual
Infiltration Considerations
 Plant precipitation interception differences
Row crop vs grass or woodland
Annual vs perennial
 Soil infiltration differences
Clay, loam, sand, gravel
 Rooting depth
Deeper rooted plants provide deeper root
channels when they die.
Transpiration Influences
 Plant type
 Size of stomatal opening
 Light
 Plant density
 Wind speed
 Temperature
 Humidity
 Soil moisture
 Season & region
http://en.wikipedia.org/wiki/File:Tomato_leaf_stomate_1-color.jpg
Evapotranspiration
Northwest
40 % of ave.
annual
precipitation
Southwest
100 % of ave.
annual
precipitation
Northeast
40 % of ave.
annual
precipitation
http://geochange.er.usgs.gov/sw/changes/natural/et/
Water Movement
The lower 5 miles of atmosphere moves
approximately 40,000 billion gallons of water vapor
over the contiguous United States each day.
What happens to the
precipitation on the U.S.?
% of Precipitation
that goes to:
2%
28%
Evapotranspiration
67%
Surface water outflow
Groundwater outflow
Consumptive use
Water Use
(Evapotranspiration)
Plant
Emergent plant
Full Cover
(% pan evaporation) (% pan evaporation)
Corn
30%
Soybeans
20%
83%
(at tassel)
110%
(70 days)
Condensation Influences
 Temperature
 Amount of water in the
atmosphere
 Atmospheric pressure
 Presence of condensation
nuclei
R. Dow, MSUE
Land Use Water Impacts
Infiltration Rates
<---Greatest----------------------------------------------------------Lowest--->
High organic > Medium organic residue > Low organic residue
Sandy soil >
Loam > Silty >
Clay soil
Forest > Pasture > Crop land > Bare earth > Buildings > Pavement
Runoff Rates
<-- -Greatest---------------------------------------------------------Smallest--->
Low organic residue > Medium organic residue > High organic residue
Clay soil
Silty soil
Loam soil
Pavement > Buildings > Bare earth > Crop land > Pasture > Forest
Http://omp.gso.uri.edu/ompweb/doee/teacher/pdf/act10.pdf
Crops used for biofuels
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Miscanthus
Switchgrass
Willow
Popular
Corn
Sorghum
Sugar cane
Alfalfa stems
Soybeans
Brasssicas
Algae
Oil Producing Crops
Plant
Yield (seed
lbs/acre)
Biodiesel
gal/acre
Plant
Yield (seed
lbs/acre)
Biodiesel
gal/acre
Corn
7800
18
Safflower
1500
83
Oats
3600
23
Rice
6600
88
Cotton
1000
35
Sunflower
1200
100
Soybean
2400
48
Peanut
2800
113
Mustard
1400
61
Rapeseed
2000
127
Camelina
1500
62
Coconut
3600
287
Crambe
1000
65
Oil palm
6251
635
Source: Biofuel Variety Trials Factsheet, USDA-ARS and WSU, Prosser, WA
Biomass Production,
Potential Ethanol Production
& Needed Land Area
Million acres
Biomass Ethanol needed for 35
Feedstock
(Tons/ (gal/acre) billion gallons
acre)
of ethanol
Corn grain1
4.5
456
12.6
Corn stover2
3.3
300
19.1
Corn total
7.8
756
7.6
Switchgrass
4.6
421
13.6
Miscanthus
13.2
1198
4.8
% 2006 harvested
U.S. cropland
24.4
37.2
14.8
26.5
9.3
The Hydrologic Cycle and
Biofuel Crop Considerations
 Water usage for biofuel crop production
 Biofuel crop versus other land use
 Crop impacts on water needs by other
organisms
 Crop impacts on runoff and infiltration
 Methods to decrease the water use impacts
of biofuel crop production will promote their
agricultural sustainability
Last updated:
2011