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

Earths Water Budget OCEANS ATMOSPHERE LAND 97.5% 2.4% <. 001% No new water !

The Water Cycle Water Cycle

Water 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 LOWHIGH SunlightCloudySunny HumidityLowHigh TemperatureLowHigh WindCalmwindy

Water Quality

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 soilimpacts temperature Soil texture

Infiltration & Runoff Influences Slope Slope Soil typepermeability Soil typepermeability Impermeable surfaces in developed areas Impermeable surfaces in developed areas Soil surface coverPlants and mulch or other organic matter on surface Soil surface coverPlants and mulch or other organic matter on surface Soil moisture channels –Worm holes, animal burrows, root channels all increase infiltration Soil moisture channels –Worm holes, animal burrows, root channels all increase infiltration Cultivation & management techniques such as contour farming, terracing, grassed filter strips, etc. Cultivation & management techniques such as contour farming, terracing, grassed filter strips, etc.

Runoff Control Runoff Management Slope Management Soil Management Crop Management Diversion channels Terraces Contouring Engineered structures Cover crops Vegetative barriers Strip cropping Inter-cropping Conservation tillage Mulching Contour farming Breaking up hardpan Vegetative barriers Water reservoirs Check dams Grassed waterways

Crop selection related to the water cycle Seasonal differences: frozen vs. non-frozen Soil coverNRCS 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

Northwest 40 % of ave. annual precipitation EvapotranspirationEvapotranspiration. Southwest 100 % of ave. annual precipitation Northeast 40 % of ave. annual precipitation

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.

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

Water Use (Evapotranspiration) PlantEmergent plant (% pan evaporation) Full Cover (% pan evaporation) Corn 30% 83% (at tassel) Soybeans 20%110% (70 days)

R. Dow, MSUE Condensation Influences Temperature Amount of water in the atmosphere Atmospheric pressure Presence of condensation nuclei

Land Use Water Impacts Infiltration Rates High organic > Medium organic residue > Low organic residue Sandy soil > Loam > Silty > Clay soil Forest > Pasture > Crop land > Bare earth > Buildings > Pavement Runoff Rates Low organic residue > Medium organic residue > High organic residue Clay soil Silty soil Loam soil Pavement > Buildings > Bare earth > Crop land > Pasture > Forest

Crops 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, WABiofuel Variety Trials Factsheet, USDA-ARS and WSU, Prosser, WA Oil Producing Crops PlantYield (seed lbs/acre) Biodiesel gal/acre PlantYield (seed lbs/acre) Biodiesel gal/acre Corn780018Safflower Oats360023Rice Cotton100035Sunflower Soybean240048Peanut Mustard140061Rapeseed Camelina150062Coconut Crambe100065Oil palm

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 grain Corn stover Corn total Switchgrass Miscanthus

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