Presentation at Utah Hay and Forage Symposium February 1, 2013 By L. Niel Allen Irrigation Extension Specialist Utah State University

Transcription

1 Presentation at Utah Hay and Forage Symposium February 1, 2013 By L. Niel Allen Irrigation Extension Specialist Utah State University

2 When are Irrigation Strategies for Water-Short Years Important Limited irrigation water supplies Allocation of water between different crops High irrigation water costs Drought Could be every year

3 Basic Principles Alfalfa uses water is most efficiently during spring growth (1 st and perhaps 2 nd cutting). About 5 acre-inches of ET per ton (1 st cutting) About 7 acre-inches of ET per ton (later cuttings) Under-irrigation results in higher irrigation efficiencies (slight deficit irrigation) It takes water to maintain alfalfa with little growth. Most alfalfa varieties will go into dormancy. Alfalfa is generally considered drought tolerant.

4 Basic Principles (Continued) There are variable costs to growing alfalfa (irrigating, fertilizer, pest control, harvesting, etc.). Focus on most productive alfalfa land (best soils, best alfalfa stem density, least weeds, youngest alfalfa, best irrigation systems). Focus on land with most efficient irrigation application. Extra water does not produce extra yield. Enough but not extra

5 Strategy Irrigate when Alfalfa Water Use Efficiency is the best. Irrigate to insure a good 1 st cutting. Alfalfa can produce more tons per unit of water during the first cutting. Can provide better utilizes the winter precipitation. Then focus on land that can be irrigated the entire irrigation season.

6 Limited Irrigation of Alfalfa in the Great Plains and Intermountain West Troy Bauder, Neil Hansen, Brad Lindenmeyer, Jim Bauder, and Joe Brummer

7 IMPLICATIONS OF DEFICIT IRRIGATION MANAGEMENT OF ALFALFA - Steve Orloff, Dan Putnam, Blaine Hanson, and Harry Carlson Changes in alfalfa water use (ET) and water use efficiency over the growing season. (Sacramento Valley)

8 Limited Irrigation of Alfalfa in the Great Plains and Intermountain West Troy Bauder, Neil Hansen, Brad Lindenmeyer, Jim Bauder, and Joe Brummer

9 Strategy Improve Irrigation System Coefficient of Uniformity

10 Irrigation Depth Distribution (80% Coefficient of Uniformity) Irrigation Depth (in) Average Irrigation of 15 inches

11 Irrigation Depth Distribution 50 % of Area Fully Irrigated Irrigation Depth (in) Area Receiving less than Indicated Depth (%) CU=70% CU=80%" CU=90% Assumes ET from Irrigation of 15 inches Area of deep percolation

12 Irrigation Depth Distribution 75 % of Area Fully Irrigated Irrigation Depth (in) Area Receiving less than Indicated Depth (%) CU=80%" CU=90% CU=70% Area of deep percolation Typical irrigation recommendation for a full water supply (75% of area fully irrigated)

13 Irrigation Depth Distribution 25 % of Area Fully Irrigated Irrigation Depth (in) Area Receiving less than Indicated Depth (%) CU=70% CU=80%" CU=90% Area of deep percolation

14 Yield from Irrigation Only Additional Yield is from Precipitation Summary of Impact of Deficit Irrigation and Irrigation System Coefficient of Uniformity. (Net Irrigation Requirement of 15 inches from calculations not field measurements) % Area Fully Irrigated Item Units Coefficient of Uniformity 70% 80% 90% 25% (deficit Irrigation) 50% 75% (full irrigation) Irrigation (inches) Irr. Eff. (%) 95% 97% 98% Yield (tons/acre) IWUE (tons/ac-in) Irrigation (inches) Irr. Eff. (%) 85% 90% 95% Yield (tons/acre) IWUE (tons/ac-in) Irrigation (inches) Irr. Eff. (%) 66% 78% 89% Yield (tons/acre) IWUE (tons/ac-in) Assumptions: Net Irrigation Requirement of 15 inches Yields based on 0.2 tons per acre-inch maximum and WUE v. ET function Note: This is only the yield from irrigation in some area of Utah the yield from precipitation can be 2 to 3 tons per acre.

15 Yield from Irrigation Only Additional Yield is from Precipitation Summary of Impact of Deficit Irrigation and Irrigation System Coefficient of Uniformity. (Net irrigation Requirement of 25 inches. From calculations not field measurements) a % Area Fully Irrigated Item Units Coefficient of Uniformity 70% 80% 90% 25% (deficit Irrigation) 50% 75% (full irrigation) Irrigation (inches) Irr. Eff. (%) 95% 97% 98% Yield (tons/acre) IWUE (tons/ac-in) Irrigation (inches) Irr. Eff. (%) 85% 90% 95% Yield (tons/acre) IWUE (tons/ac-in) Irrigation (inches) Irr. Eff. (%) 66% 78% 89% Yield (tons/acre) IWUE (tons/ac-in) Assumptions: Net Irrigation Requirement of 25 inches Yields based on 0.2 tons per acre-inch maximum and WUE v. ET function

16 Limited Irrigation of Alfalfa in the Great Plains and Intermountain West Troy Bauder, Neil Hansen, Brad Lindenmeyer, Jim Bauder, and Joe Brummer Partial Season-only first cutting Deficit Irrigation was maximum irrigation of 1.5 inches per week. 0

17 Leaking Gaskets and Drains Waste Water

18 Example of under irrigation

19 Example of under irrigation

20 Maintained Irrigation System

21 This is the goal

22 Recommendations Improve irrigation system uniformity. Fix irrigation leaks, replace gaskets, drains, sprinklers, etc. Irrigate best land. Focus on first cutting, then irrigate the land you can keep growing during the rest of the season Implement slight deficit irrigation to improve irrigation efficiency. Don t spread water too thin that you don t have a cutting worth harvesting. Irrigation the acreage you can keep alfalfa from going dormant and producing near potential yield.

23 Recommendations for Surface Irrigation If available flow is low, irrigate fewer borders (For example, if you normally use 15 cfs for three borders, then irrigate only 2 borders if you have only 10 cfs). Turn off water when it reaches about 2/3 of the length of field to avoid or reduce runoff.

24 Questions