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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
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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
Earth’s Water Budget OCEANS ATMOSPHERE <.001% No new water ! 97.5% LAND 2.4%
Water Cycle The Water Cycle
Water Quantity Julie Doll
Evaporation 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 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 • 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 Soil Management Crop Management Conservation tillage Mulching Contour farming Breaking up hardpan Diversion channels Terraces Contouring Engineered structures Cover crops Vegetative barriers Strip cropping Inter-cropping Vegetative barriers Water reservoirs Check dams Grassed waterways
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
InfiltrationConsiderations • 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 Northeast 40 % of ave. annual precipitation Southwest 100 % 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. Around 10 % of this moisture precipitates.
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 Siltysoil 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 • Miscanthus • Switchgrass • Willow • Popular • Corn • Sorghum • Sugar cane • Alfalfa stems • Soybeans • Brasssicas • Algae
Oil Producing Crops Source: BiofuelVariety Trials Factsheet, USDA-ARS and WSU, Prosser, WA
Biomass Production, Potential Ethanol Production& Needed Land Area
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