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 outlineCourse 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

Earth’s Water Budget

Earth’s Water Budget

OCEANS

ATMOSPHERE

LAND97.5%

2.4%

<.001%

No new water !

No new water !

The Water CycleThe Water CycleWater CycleWater Cycle

Water QuantityWater Quantity

Julie Doll

Crop water needs are determined by considering crop, soil type and region as well as climatic conditions

CLIMATIC CONDITION

CROP WATER NEEDS

LOW HIGH

Sunlight Cloudy Sunny

Humidity Low High

Temperature Low High

Wind Calm windy

Water QualityWater Quality

Evaporation ConsiderationsEvaporation Considerations 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 InfluencesEvaporation 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 InfluencesInfiltration & Runoff Influences 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. 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 ControlRunoff Control

Runoff Management

Slope Management

Soil Management

Crop Management

Diversion channelsTerracesContouringEngineered structures

Cover crops Vegetative barriersStrip croppingInter-cropping

Conservation tillageMulchingContour farmingBreaking up hardpan

Vegetative barriersWater reservoirsCheck damsGrassed waterways

Crop selection related to the water cycle

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 ConsiderationsInfiltration 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 InfluencesTranspiration 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

Northwest40 % of ave.

annual precipitation

EvapotranspirationEvapotranspiration

Southwest100 % of ave.

annual precipitation

Northeast40 % of ave.

annual precipitation

http://geochange.er.usgs.gov/sw/changes/natural/et/

Water MovementWater Movement

The lower 5 miles of atmosphere moves approximately 40,000 billion gallons of water vapor over the contiguous United States each day. Around 10 % of this moisture precipitates.

What happens to the precipitation on the U.S.?

What happens to the precipitation on the U.S.?

Evapotranspiration Surface water outflow

Groundwater outflow Consumptive use

67%

28%

2% % of Precipitation that goes to:

Water Use (Evapotranspiration)

Water Use (Evapotranspiration)

Plant Emergent plant(% pan evaporation)

Full Cover(% pan evaporation)

Corn 30% 83%(at tassel)

Soybeans 20% 110%(70 days)

R. Dow, MSUE

Condensation InfluencesCondensation Influences Temperature Amount of water in the

atmosphere Atmospheric pressure Presence of condensation

nuclei

Land Use Water ImpactsLand Use Water Impacts Infiltration Rates

<---Greatest----------------------------------------------------------Lowest--->High organic > Medium organic residue > Low organic residue Sandy soil > Loam > Silty > Clay soilForest > 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 soilPavement > Buildings > Bare earth > Crop land > Pasture > Forest

Http://omp.gso.uri.edu/ompweb/doee/teacher/pdf/act10.pdf

Crops used for biofuelsCrops used for biofuels Miscanthus Switchgrass Willow Popular Corn Sorghum Sugar cane Alfalfa stems Soybeans Brasssicas Algae

Source: Biofuel Variety Trials Factsheet, USDA-ARS and WSU, Prosser, WA

Oil Producing CropsOil 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

Biomass Production, Potential Ethanol Production

& Needed Land Area

Biomass Production, Potential Ethanol Production

& Needed Land Area

Feedstock Biomass (Tons/acre)

Ethanol(gal/acre)

Million acres needed for 35 billion gallons

of ethanol

% 2006 harvested U.S. cropland

Corn grain1 4.5 456 12.6 24.4Corn stover2 3.3 300 19.1 37.2

Corn total 7.8 756 7.6 14.8Switchgrass 4.6 421 13.6 26.5Miscanthus 13.2 1198 4.8 9.3

The Hydrologic Cycle and Biofuel Crop Considerations

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