Center Pivot Irrigation for Corn: Water Management and System Design Considerations

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1 Center Pivot Irrigation for Corn: Water Management and System Design Considerations Steve Hines Extension Educator University of Idaho Jerome County December 12, 2013

2 This talk summarizes UI Bulletin BUL 881 Center Pivot Irrigation for Corn: Water Management and System Design Considerations in Southern Idaho By S. Hines and H. Neibling Or Google: University of Idaho Bulletin 881

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4 Factors Affecting Corn Yield Dr Fred Below, University of Illinois Factor Weather (Irrigation) Nitrogen Hybrid Previous Crop Plant Population Tillage Growth Regulators Weight on Yield (%) 27% %

5 Outline Impact of stress on yield depends on crop stage Water stress may occur because insufficient water is applied to match ET Irrigation scheduling problem Irrigation design problem Water stress may occur because part of applied water is lost to surface runoff.

6 Critical growth stages V6 V7-V12 Pollination

7 Drought Stressed Ears

8 Outline Impact of stress on yield depends on crop stage Water stress may occur because insufficient water is applied to match ET Irrigation scheduling problem Irrigation design problem Water stress may occur because part of applied water is lost to surface runoff.

9 Timing of Crop ET and Critical Crop Stages for Magic Valley Conditions Tillering Tillering Boot - flower Boot - flower Tuber set V-6 Germination, Emergence & Early Growth Early growth Flowering Pollination Winter Grain Spring Grain Dry Beans New fall seedings Potatoes Field Corn Sugar Beets Alfalfa Date

10 Agrimet Estimated Crop ET, in/d Average 30-Year ET for Corn in the Magic Valley gpm/a 6.5 gpm/a Critical pollination and ear development stage

11 ET and Irrigation, inches 35 Bliss Corn Silage gpm/acre Scheduling deficiency AGRIMET ET Max irrigation Actual irrig /20 0 5/1 5/31 6/30 7/30 8/29 9/28 10/28 Date

12 Outline Impact of stress on yield depends on crop stage Water stress may occur because insufficient water is applied to match ET Irrigation scheduling problem Irrigation design problem Water stress may occur because part of applied water is lost to surface runoff.

13 6.5 gpm/a 7.5 gpm/a

14 6.5 gpm/a 7.5 gpm/a

15 You may not be able to supply enough water at mid-season, so how much usable water can you bank in your soil?

16 Maximum Storable Water Sandy Loam (1.7 in/ft * 0.5 = 0.85 in/ft) 1 ft: 0.8 in 2 ft: 1.7 in 3 ft: 2.6 in 50% MAD Only 40% during pollination Silt loam (2.4 in/ft * 0.5 = 1.2 in/ft) 1 ft: 1.2 in 2 ft: 2.4 in 3 ft: 3.6 in

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19 Outline Impact of stress on yield depends on crop stage Water stress may occur because insufficient water is applied to match ET Irrigation scheduling problem Irrigation design problem Water stress may occur because part of applied water is lost to surface runoff.

20 Spread the water stream over a wider area to match infiltration rate of your soil

21 Sprinkler & Infiltration rate, in/h Portneuf silt loam Kimberly, ID first pivot span infiltration 20' dia. 45' dia. 100' dia Time after irrigation is started, hours

22 Fore and Aft Booms Spread the Application Pattern & Reduce Runoff

23 Sprinkler & Infiltration rate, in/h Portneuf silt loam Kimberly, ID last pivot span Time after irrigation is started, minutes infiltration 20' dia. 45' dia. 45' + booms (75) 100' dia.

24 Sprinkler & Infiltration rate, in/h Portneuf silt loam Kimberly, ID last pivot span Time after irrigation is started, minutes infiltration 20' dia. 45' dia. 45' + booms (75) 100' dia. infiltration in surface storage

25 Reservoir Tillage Increases surface storage to minimize runoff More effective on flat fields than sloping ones Storage capacity 0-2% slopes, 0.75 inch storage 2-5% slopes, 0.5 inch storage >5% slopes, 0.25 inch storage Mini ponds tend to break down as the season progresses

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27 Application or Infiltration Rate, in/h Field area, % ft 45 ft 100 ft sandy loam field area 1320 ft pivot Distance From Pivot Point, feet

28 Reduce Pivot & linear Runoff Losses By: Choose proper application pack Use fore & aft booms to spread application pattern Limit application per revolution Use reservoir tillage (dammer-diker)

29 Growth Stage Final Irrigation Considerations Plant Moisture % Days to maturity Water use to maturity (inches) Blister (R2) Dough (R4) Full Dent (R5) ¼ Milk Line ½ Milk Line ¾ Milk Line Physiological Maturity

30 Summary - Pivots and Linears Avoid excessive early and late-season irrigation but. Fill the soil profile early Pay attention to critical ET timing of corn for maximum yield Use faster rotation speeds or dammer-diking to reduce runoff You can grow good corn on 80% water with good management Refer to your Proceedings or UI Bulletin 881

31 Questions?