Clinton Shock¹, Erik Feibert¹, Eric Eldredge¹, Monty Saunders¹, Marvin Butler², Claudia Campbell², Fred Crowe², R. Bafus², Peter Sexton³, and Jim Klauzer4

Western Region Project W-128: Microirrigation: Management Practices to Sustain Water Quality and Agricultural Productivity, San Antonio, TX, November 6-8, 2001

¹Malheur Experiment Station, OSU, 595 Onion Ave., Ontario, OR 97914 Telephone (541) 889-2174 Email Clinton.Shock@oregonstate.edu
 ²Central Oregon Agricultural Research Center, OSU, 850 Dogwood Lane, Madras, OR 97741 Telephone (541) 475-7107
³University of Maine
⁴Clearwater Supply, Ontario, OR

Drip irrigation systems are being intensively tested on alfalfa for seed, alfalfa for hay, potatoes, onions for bulbs, onions for seed, poplar trees, yew shrubs, and carrot seed. Observations are also being made on drip system serving mint, sugar beets, and wheat fields. Treatments are being evaluated based on crop yield, crop quality, and water use efficiency. Grids of sensors are being used to examine the vertical and horizontal movement of water through the soil profile from drip lines. Various soil moisture monitoring equipment is being evaluated for use as irrigation scheduling aids in growers fields.

Highlights are as follows:

1. The project demonstrated that onions required relatively little fertilizer N when irrigated with SDI.

2. Potato water use efficiency was very high using SDI. Potato irrigation criteria proved to be wetter using SDI than has been previously shown for potato irrigation criteria in furrow or sprinkler irrigation systems, but less total water was required using SDI than with the other irrigation systems.

3. Water use efficiency of SDI is greater than micro-sprinklers for poplar saw-log production.

4. When a grower's irrigation systems were changed from surface furrow irrigation to SDI, the response of alfalfa seed yield was favorable.

5. Four semi-permanent buried drip irrigation systems have been established on a cooperating grower's farm, and these are being used to examine the possibility of SDI through an entire crop rotation.

6. Alfalfa seed yield using SDI was high with 13 acre-inches of water per acre, compared with wetter or drier treatments.

7. Poplar irrigation was more efficient in converting water into wood with surface drip irrigation than with micro-sprinklers.

8. Carrot seed was more productive and of better germination when produced with drip irrigation than with sprinkler irrigation. Surprisingly, the drip irrigation criteria was of little consequence.

2. Tape configuration in alfalfa seed: Tape placement and alfalfa plant spacing for the alfalfa seed above is as follows: the alfalfa is 30 inches between rows and there is 5 feet between the tapes. Tape buried 12 inches deep between every other row of alfalfa is being compared with tape buried as deep as mechanically possible; 15-18 inches deep between every other row of alfalfa.

3. Irrigation criteria for potato. Potatoes were grown with successively drier irrigation criteria ( -15, -30, -45, and -60 kPa) with five replicates of each treatment. A single drip tape served two rows of potatoes to reduce tape cost, enhancing economic feasibility. Soil water was monitored automatically every hour using granular matrix sensors. Plots were irrigated automatically as often as every 6 hours, as required.

4. Tape placement for potatoes: The potato rows were spaced 3 feet apart. The treatments resulted in tapes 3 or 6 feet apart, respectively.

1. Buried 3-4 inches below the soil surface over every potato seed piece row.

2. Buried 3-4 inches deep between two rows of potatoes in a single raised bed.

5. Leaching avoided: Three vertical grids of soil moisture sensors were used in the soil perpendicular to the potato and onion crop rows and drip tapes to evaluate vertical and horizontal soil water movement. (The soil in all the other trials were measured for soil water potential or soil water content.)

6. Reduced N applications: Onions were grown using 0, 50, 100, 150, 200, 250, and 300 lb N/acre with an irrigation criterion of -20 kPa. The N was split into small increments during the season. Both the current N recommendations and commercial applications are in the range of 300 to 350 lb N/acre. The resulting onion bulb yield and grade are being evaluated after conventional storage. The economic value of the crop will be estimated as well as the most environmentally sound and economically advantageous N rates.

7. Soil moisture monitoring in growers' drip-irrigated onion fields. Soil water potential was monitored using GMS every 8 hours in three cooperating growers' fields using AM400 Soil Moisture Data Loggers With Graphic Displays (M. K. Hansen Co., East Wenachee, WA).

8. Demonstration of the continuous use of tape. Tape was buried 6-8 inches deep on a cooperating farm in 2000 (Ontario Farms, Ontario in cooperation with David Blaylock) where a sequence of crops is being planted to establish the variability of long term use of tape in the same field without removal. Onions, wheat, and sugar beets are being grown in rotation in successive years on 3 acre plots. Mint is being grown on an additional 3 acres with long term SDI. These plots have been monitored for water application and soil moisture in 2000. Water flow measuring and soil moisture monitoring equipment were installed this spring.

9. Hybrid poplar water use and irrigation systems. Five irrigation treatments are being evaluated to increase irrigation efficiency: three irrigation rates using mini-sprinklers and two alternative drip irrigation systems. Water application, soil water potential, applied water, and tree growth are being measured in all four replicates of the trial.

10. Carrot seed. Carrot grown for seed is a very important high-value crop in central Oregon. Disease tolerances are low in the crop, particularly Alternaria radicina and A. dauci. Employing a subsurface drip system to deliver irrigation water may decrease potential for disease infection and spread within the carrot canopy and may provide long term benefits of decreasing water and fertilizer use. Towards this end, a preliminary trial is being conducted to observe carrot yield and disease incidence with five different irrigation thresholds (-15, -30, -60, -90, and -120 kPa soil water potential). The first season of this trial is almost completed. There is a plot of sprinkler irrigated carrots for a comparison, irrigated at a threshold of -60 kPa.

2000 Results: The amount of water that was applied from May (when treatments were imposed) through mid August was approximately 7.5 inches in the drier treatments (-120 kPa) to 25 inches in the wetter treatments (-15 kPa). The sprinkler-irrigated treatment used about 16 inches. Seed yield per acre was not very sensitive to irrigation threshold within the drip-irrigated treatments. However, the drip-irrigated lb/ac had greater yields (425 lb/ac) than did the sprinkler-irrigated carrots (335 lb/ac). Seed from the drip-irrigated carrots had higher germination rates (85 to 91%) than did the seed from the sprinkler-irrigated carrots (77%). There was no observable disease incidence in the plots prior to harvest. There was no statistical difference in disease incidence on the seed between the drip and the sprinkler-irrigated carrots.

11. Onion seed. Onion grown for seed is a very risky, but potentially very profitable, crop. The fungus Botrytis allii may blight seed stalks, umbels, and florets in onion and has been known to cause complete stand loss. As with carrots, SDI may provide benefits in decreasing disease spread and so decrease some of the risk associated with this crop. Trials using SDI in seed onion are being conducted to look at the effect of tape placement (0, 5, 10, and 20 cm depths) on disease incidence and yield. In 2001, the plots were initially irrigated the same as last year, however due to the high incidence of Botrytis and especially soft rot, the threshold for the average soil moisture potential was changed to -55 kPa.

2000 Preliminary Results: Disease incidence was not severe in the 2000 growing season, and there were no statistically significant differences for incidence of Botrytis between the drip and sprinkled irrigated plots. Seed yield was greater in the drip plots than in the sprinkler-irrigated plots. Within the drip plots there was a trend for seed yield to be greatest at a tape depth of four inches.

2001: The disease incidence this year is quite pronounced as compared to last year. On May 23 there was a thunderstorm with hail and high winds, the plots were on the edge of the storm and received only slight to minimal damage, the further east, the more the damage. There were very few plants where the hailstones actually penetrated the scape. In 2000 there was no noted incidence of soft rot, this year there is by comparison, considerable soft rot. The soft rot was showing in the plants prior to the hailstorm. On June 6 there was a rating taken on both soft rot and Botrytis. All the female plants obviously affected by soft rot in the drip plots were counted and four reps of two female rows each were counted in the sprinkled plots. There was a statistical difference of incidence between the sprinkled plots and the drip plots, with the sprinkled plots having nearly four times the incidence of soft rot. There was no statistical difference within the drip treatments. Botrytis was rated by taking a 3 foot representative sample from one of the female rows within each plot and counting the number of obviously infected plants. There is no statistical difference of Botrytis incidence between any of the plots sprinkled or drip. Seed yields have not been determined.

12. Water stress on yew. Hicksii yews are being grown experimentally under variable water stress using SDI to optimize taxol production. The effect of water stress on other chemical components in the yew leaves is currently being examined.

13. Alfalfa hay. Preliminary observations on the use of SDI for alfalfa hay production will be made in 2002. The SDI system was installed this fall under an area that will be planted to an alfalfa variety trial.

14. Shelter belt. A drip irrigation system was established on a shelter belt of shrubs and trees in 2001. The shelter belt was successfully irrigated.

EPA 319, Oregon Department of Environmental Quality, Oregon Watershed Enhancement Board, OSU Agriculture Research Foundation, OSU-IPPC, Idaho Eastern-Oregon Onion Committee, Nelson Irrigation, Fresno Valves, T-Tape, Netafim, Irrometer, Clearwater Supply, and US Bureau of Reclamation

Refereed Articles

Shock, C.C., E.B.G. Feibert, M. Seddigh, and L.D. Saunders. 2002. Water Requirements and Growth of Irrigated Hybrid Poplar in a Semi-arid Environment in Eastern Oregon. Western Journal of Applied Forestry. 17(1)46-53.

Shock, C.C., E.B.G. Feibert, L.B. Jensen. R.L. Jones, G.W. Capps and E. Gheen. 2001. Changes toward sustainability in the Malheur-Owyhee watershed. In W.A. Payne, D.R. Keeney, and S. Rao (eds). Sustainability in Agricultural Systems in Transition Proceedings, ASA Special Publication. American Society of Agronomy, Madison, WI. p 97-106.

Extension Publications

Shock, C. C. 2001. Drip Irrigation: An Introduction. Oregon State University Extension, Corvallis OR. EM8782. Also available at
http://extension.oregonstate.edu/umatilla/mf/sites/default/files/Drip_Irrigation_EM8782.pdf

Jensen, L., and C. C. Shock. 2001 Strategies for Reducing Irrigation Water Use. Oregon State University Extension, Corvallis OR. EM8783.  Also available at
http://extension.oregonstate.edu/catalog/pdf/em/em8783.pdf

Oregon State University Agricultural Experiment Station, Special Report 1025.

Sexton, P., C. Campbell, F. Crowe, and C. C. Shock. 2001. Drip Irrigation of Seed Onion in Central Oregon: Preliminary Data on the Effect of Tape Placement. p 155-158.

Sexton, P., C. Campbell, R. Bafus, F. Crowe, and C. C. Shock. 2001. Drip Irrigation of Seed Carrots in Central Oregon: Preliminary Data on the Effects of Irrigation Threshold on Seed Yield. p 194-196.

Oregon State University Agricultural Experiment Station, Special Report 1029.

Shock, C.C., L.D. Saunders, B. Horn, E. Saunders, and J. Klauzer. 2001. Adaptation of Subsurface Drip Irrigation to Alfalfa Seed Production. p 19-21. Also available at http://www.cropinfo.net/AnnualReports/2000/AlfSeedDrpRpt2000.htm

Shock, C. C., E. B. G. Feibert, and L. D. Saunders. 2001. Plant Population and Nitrogen Fertilization for Subsurface Drip-irrigated Onions. p 52-59.  Also available at http://www.cropinfo.net/AnnualReports/2000/ondrip00.htm

Shock, C.C., E.B.G. Feibert, and L.D. Saunders. 2001. Micro-irrigation alternatives for hybrid poplar production, 2000 trial. p 93-101. Also available at http://www.cropinfo.net/AnnualReports/2000/Popirr2000.htm

Shock, C. C., E. P. Eldredge, and L. D. Saunders. 2001. Drip-Irrigation Management Factors for Umatilla Russet Production. p 122-127. Also available at http://www.cropinfo.net/AnnualReports/2000/DripFactorial00.htm

Shock, C. C., E. P. Eldredge, and L. D. Saunders. 2001. Early and Late Harvest Drip-Irrigated Red and Russet Varieties. p 128-134. Also available at http://www.cropinfo.net/AnnualReports/2000/00EarLatRedRus.htm

Others

Shock, C. C, A. Corn, S. Jaderholm, L. Jensen, and C. A. Shock. 2001. Evaluation of the AM400 Soil Moisture Data Logger to aid irrigation scheduling. International Irrigation Show 2001 Proceedings, The Irrigation Association. p 111-116. Also available at
http://www.Cropinfo.net/OtherReports/HansenIA2000.htm

Shock, Clinton. C., Eric P. Eldredge, Lamont D. Saunders, and Erik G. B. Feibert. 2001. Optimum Soil Water Potential and Drip Tape Position for Potato (Solanum tuberosum L.) Drip Irrigation., The Potato Association of America 85th Annual Meeting, April, 2001, St. Augustine, Florida.

SUPERVISION OF STUDENT RESEARCH HELP:

Katie Kimberling, Eastern Oregon Univ. Vale, OR
Cedric Shock, University of Oklahoma Ontario, OR
Misty Janes, Nebraska College Ontario, OR
Daniel Horn, New Plymouth H.S. New Plymouth, ID
Benjamin Horn New Plymouth H.S. New Plymouth, ID
Andrew M. Sadowski OSU Vale, OR
Andrew Nishihara Adrian H.S. Adrian, OR
Scott Jaderholm BYU Ontario, OR
Fawn L. Pettet Boise State University Ontario, OR

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