2. Woody Woodruff Method University of Missouri –a chart !!! –a “checkbook” method –uses historic water use data –originally for corn on claypan soils took into account the need to dry soil out at end of season –others have modified it University of Nebraska Gregory et al. (Ag Engineering) have computer program Commercial Ag Program will regionalize the charts

5. Soybean Water Use Planted: May 22 Length: 120 days Cairo, IL historic weather Total water: 18.8 inches

8. 0.8 in rain

9. 0.4 in rain

10. 0.8 in rain 0.4 in rain 2.0 in rain

11. 0.8 in rain 0.4 in rain 2.0 in rain 0.6 in rain

12. 0.8 in rain 0.4 in rain 2.0 in rain 0.6 in rain 1.5 in irrigation We never want to cross below the bottom line as it represents drought conditions for our crop and thus yield loss. Therefore, a 1.5” irrigation takes place on June 10.

13. 0.8 in rain 0.4 in rain 2.0 in rain 0.6 in rain 1.5 in irrigation 6/16 Next irrigation date

14. 0.8 in rain 0.4 in rain 2.0 in rain 0.6 in rain 1.5 in irrigation Continue using the same strategy through the season. Don’t bother plotting rainfall amounts less then 0.25 inches, since most of it evaporates before getting into the ground. Plan last irrigations based on conditions in your field & rain- fall forecasts. 1.5 in irrigation 0.4 in rain 2.0 in rain 0.4 in rain

15. Bootheel Irrigation Survey, 2000

16. Reinbott, Columbia, MO 2001

17. Information needed to make your own Woodruff Irrigation Chart Information on crop –corn: Relative Maturity (RM) –soybean: Maturity Group –cotton: no special information Emergence date Soil type County in Missouri where crop is

22. Http://agebb.missouri.edu/irrigate/woodruff