2. New Legislation Act 148 – Water use reporting, mapping of groundwater information, consider need for addition legislation Act 177 – Water use conflict resolution Governor - Water Legacy Act http://www.michiganlegislature.org/

3. Irrigation Scheduling Know available soil water for each unit Known depth of rooting for each crop Know allowable soil moisture depletion at each stage of plant growth Use evapotranspiration data to estimate crop water use Measure rainfall in each field Use container capacity for nursery crops

4. Why Schedule Prevent stress – health of plant - yield loss – appearance Maximize water use efficiency – beneficial use of resource Minimize leaching of nitrates or pesticides

5. Irrigation amount The amount of water available to the plant is a function of root depth and soil available water For example: plant with a rooting depth of 2 ft on “Coarse-textured loamy sand” has.08 in/in X 2 ft X 12 in/ft = 1.98 in For an allowable depletion of 50% - a 1 in application would replenish available water

6. Reference Evapotranspiration ETo or potential evapotanspiration represents a well watered, fully developed plant such as grass Reference evapotranspiration is multiplied by a crop coefficient to obtain the ET rate for a specific crop The crop coefficient varies throughout the growing season For Example Corn at 20% = 0.67 at 50%=1

7. Estimates of ET Max and min temperatures Relative humidly Wind Net radiation Modified Penman to estimate ETo U of Wisconsin web site http://www.soils.wisc.edu/wimnext/et/miet.html

8. ET Measurements Weighing Lysimeters Uniformity of soil important Representative plant growth

9. For Annual Crops Depth of root zone increases during the growing season Allowable soil moisture depletion varies with each stage of plant growth

11. Methods to Estimate Soil Moisture Feel and Appearance Electrical resistance – electrodes on blocks in soil Tensiometers – measures soil moisture tension Must be measured at a range of depths in root zone

14. Irrigation Scheduling Methods All methods require keeping sufficient records Appearance and feel of soil – must look at a range of depths in the root zone Checkbook method – inputs are rainfall and irrigation – output ET – Automated spreadsheet will be available by Jan 15 http://www.extension.umn.edu/distribution/cropsystems/DC1322.html “SCS-Microcomputer Irrigation Scheduling Package” 1992 Computer simulations