WIND EROSION EQUATION Recent Changes (NAM) USDA-NRCS

1. WIND EROSION EQUATIONRecent Changes (NAM)USDA-NRCS

2. Wind Erosion continues to be a serious problem in the semiarid and arid regions of the US.

3. The Good Old Days

4. The Good Old Days cont.

5. WEQ Changes made! • WEQ has been updated to account for irrigation effects, random roughness and I Factor adjustments. • WEQ changes are outlined in the new edition of the National Agronomy Manual.

6. Introduction WEQ Excel Spreadsheet • Cover NAM changes • Changes to Ridge Roughness • Addition of Random Roughness • Quick intro to the Excel spreadsheet • Demo how to edit and make changes • Answer Questions

7. Spreadsheet History • Began as a spreadsheet by Tom Keep • Then Circular 2, NAM amendment Sept. 12, 1997 was incorporated • SGe calculations added, 1998 • Krd-Ridge Roughness formulas added in 1998

8. Circular 2 Changes • I Adjustment for Irrigation -Above 180 no adjustment -180 or less, reduce one I class • IF – ‘Irr. Factor’ reduces Erosive Wind Energy (EWE) for mgt period • Random Roughness (Krr) combined with Ridge Roughness (Krd)

9. ADJUSTMENTS TO “I” • Irrigation adjustment (IF) -adjustment applies to all soils

10. EWE IRRIGATION ADJUSTMENT • Effects of wet soil is accounted for by adjusting the EWE for the mgt period • Bare wet soil remains non-erodible wet: • 1 day for coarse textured soils • 2 days for medium textured soils • 3 days for fine textured soils • See sheet “WEG tab” for table

11. ADJUSTMENTS TO “I” - IRRIGATION

12. “Krr” RANDOM ROUGHNESS FACTOR • Soil cloddiness raises the threshold wind speed at which erosion begins • Provides sheltered area among clods where moving soil can be trapped • Spreadsheet reduces RR (clodsize) by one half after 15 days.

13. “Krr” RANDOM ROUGHNESS FACTOR • Non-oriented surface roughness • Cloddiness • Usually created by tillage implements • Values represented as standard deviation, in inches, of roughness heights • Use Random Roughness-Guidance sheet • Roughness assigned to each tillage implement (ideal conditions)

14. Random Roughness - Krr

15. Ridge Roughness- Krd • Revised NAM has new tables • Based on I values and Preponderance • Low Preponderance values indicate less of the erosive wind is from the prevailing wind direction. • Higher Krd values indicate that ridges are less effective • Krd can be lower than 0.5 now

16. Irrigation Input Requirements • Enter the number of Irrigations, including pre-plant and post harvest irrigation • “Non-erodible wet days” will be calculated based on soil texture (WEG) • Drip irrigation poses a problem. Need to estimate the % of surface that is non-erodible wet

17. Circle Irrigation The soil texture determines the number of non-erodible wet days (1,2,or 3) per irrigation It takes this system 96 hours to make one complete circle. For WEQ this is one irrigation. Day 3-24 hrs Day 4-24 hrs Day 1-24 hrs Day 2-24 hrs

18. Field Width • With the WEQ Speadsheet, field width is the distance across the short side of the field or average short side of a polygon.

19. Field Width vs Unsheltered Distance Field Width

20. Field Width vs Unsheltered Distance • The Excel Spreadsheet model will determine L using the length/width ratio of the field, the angle of deviation, wind preponderance and the resulting wind erosion direction factor.

21. Computer Requirements • Need 486 minimum. • 586 is better • Windows 95, 98, or NT • Excel version 7.0 • 16 mg of RAM or better • File name WEQvs8.01.xls

22. INSTR sheet • Wind Erosion Model Worksheet Legend -Definitions • Describes input data and column headings • New-Krd, Krr, IF, No. of Irr, and TWF Read this sheet first.

23. Res WKS sheetRequired Inputs • Operation Dates • Crop Names • Operations • Percent Flat Residue • Number of irrigation per mgt period • Yield adjustment • Prod., Farm, Tract, Field, C, I, Field Width, LW ratio, Tillage Dir, Field Dir, Irr (y/n)

24. Calc sheet • Detailed calculations by Mgt Period • Note Krd, Krr, and IF factors added here • No inputs needed or allowed

25. Data Tables • Crop table -Need to maintain crop data; residue produced and green growth • Tillage table -Residue reduction -Random roughness assigned to tillage

26. Data Tables cont. • Climate data, the wind direction, EWE, and Preponderance must be added for climate stations in your state.

27. Summary • If Users have a basic understanding of the EXCEL spreadsheet, they can use this model. • State Agronomist should become familiar with the wind data (climate file), crop data, and operation (tillage) files before beginning use in a new state.

28. Limitations • We can not change tillage direction in each mgt period. • Need to create templates and save for later use. • It does not allow for crusting (no I factor adjustment for a period of crusting).

29. Limitations • Growth curve data is limited • Do not have SGe curves for all crops both green and dry

30. Where to get more information • Call State Agronomists for assistance: • State Agronomists can call: Mike Sporcic, michael.sporcic@nm.usda.gov , 505-761-442 or,

31. Where to get more information • Gary Tibke– (785)537-5541 tibke@weru.ksu.edu • Lorenz Sutherland--(719)384-5408 lorenz.sutherland@co.usda.gov • Websites for WEQ www.nm.nrcs.usda.gov/techserv or www.weru.ksu.edu/nrcs We’re Done

32. Questions & Short Demo END

33. The End