State or Agency: Department of Agronomy and Horticulture, Agricultural Experiment Station, New Mexico State University, Las Cruces, NM and NMSU Agricultural Science Center at Farmington, NM

Title: Subsurface Drip Irrigation for Northwestern New Mexico

Principal Investigator:  Mick O’Neill
 

A. Subsurface Drip Irrigation (SDI) on Field Crops

1) Summary
An 8-acre SDI trial was established in 2002 after system installation in 2001.  Four tape depths were evaluated with different field crops.   During 2002 alfalfa, beans, corn, and potatoes were grown at each of the different tape depths.  The rotation for 2003, which required a low-residue crop to follow a high residue crop, included alfalfa, corn, and potatoes.   Crops were evaluated and stand establishment, water-use, and final yield.

2) Highlights
During 2002, alfalfa germinated only in areas immediately above the tape.  In order to improve plant stand in 2003, alfalfa was drilled into the existing stand and sprinkler irrigated approximately every other day for one month.  Growth of the existing stand improved but satisfactory emergence of the newly planted material was not obtained.  It is known that allelopathic competition can prevent germination of reseeded alfalfa from several weeks to over one year.  It appears that this was the case for poor establishment of reseeded aflafla in 2003.

Small, two-row planting equipment for potatoes was used in the large plots (25 x 400 feet) to successfully obtain uniform plant stands in all tape depth treatments.
Corn stand were directly related to tape depth ranging from a low of 64% in the 9-inch treatment to a high of 98% in the 3-inch treatment.
 

Tape depth, inches	Percent stand
3	98.0
5	93.6
7	77.3
9	64.3
Mean	83.3
P	1.0008
LSD (0,05) = 12.9	CV = 9.7

Weed control was improved during 2003 but tractor-mounted spray applications still leave much to be desired.  Soil applied herbicides are not adequately activated by incorporation because of limited rainfall or no sprinkler irrigation.  RoundUp performs well in genetically modified crops such as RoundUp Ready corn but the choices are limited.  Injection of herbicides through the drip system may hold promise.

Gopher damage continues to plague the project.  Exorbitant time is devoted to splicing drip tape rather than completing other critical duties, especially early in the season when tape damage leads directly to reduced crop stands.  In closed canopy stands like alfalfa, damaged drip tape may go unnoticed until harvesting operations when swathers are bogged down in wet areas.  Drip tape buried at the deeper depths is difficult to find and may take 1-2 man-hours per gopher strike to repair.

Management of appropriate water application levels at four drip-tape depths is difficult when investigating different crops.  This is especially true with potato, which requires a favorably moist environment in the tuber profile for optimum production.  Given a uniform water application across all tape depths, the shallow depth treatments are too wet and the deep depth treatments are too dry.

B. Hybrid Poplar Production with Drip Irrigation

1) Summary
I an attempt to address several of the problems associated with SDI, especially the problems associated with gopher damage to buried drip tape, a 2-acre surface drip trial was established in 2002 to determine the production potential of hybrid poplar in the Four Corners region.  Ten hybrid poplar clones were selected.  Another trial was established in 2003 with the same ten clones plus an additional ten clones.  This trial was repeated at the OSU Malheur Experiment Station to investigate adaptation of poplar hybrids to elevated pH at two sites.

2) Highlights
Growth and chlorosis differences were noted both years between the clones grown in an alkali soil with a pH of 8.2.  Clones that established well in 2002 and demonstrated superior growth rates also grow satisfactorily in 2003. Visual rankings of chlorosis were obtained in 2002 and a Minolta chlorophyll meter was used in 2003 to determine differences between hybrid clones.  Iron chelate was injected through the drip irrigation systems and clones responded favorable as indicated by increased SPAD readings.  Screening for growth rates and chlorosis ratings will provide information for the successful selection of clones adapted to a semi-arid environment with elevated soil pH characteristic of the Four Corners region.

Gopher damage has been virtually eliminated.  During the two seasons, there have been five gopher strikes.  This is because the dripper tubing is heaver than the drip tape used in the SDI system and it is on the soil surface, which is out of the normal gopher habitat.  It is easy to see damaged dripper tubing lying on the surface thereby permitting rapid repairs.

Discussions with representatives from a large commercial farm and an excelsior manufacturing company have lead to the rapid dissemination of poplar production in the area.  Western Excelsior, which currently harvests aspen from the San Juan National forest, is interested in sustainable wood production for their factory.  The Navajo Agricultural Products Industry has agreed to initiate a 250-acre hybrid poplar plantation to begin to provide the wood required by Western Excelsior.  Cuttings of clones selected from research carried out by this project will be planted in the Spring of 2004.  Future plantations will be planted in successive years until Western Excelsior has ample supplies for their long-term requirements.

C. Students supervised

Renae Pablo, M.S. NMSU Agronomy and Horticulture Department
Kevin Lombard, Ph.D. NMSU Agronomy and Horticulture Department

D. Publications

O’Neill, Mick, Renae Pablo, and Todd Begay 2003. Subsurface drip irrigation for field crops. In: O’Neill, M.K., R.N. Arnold, D. Smeal, T. Jim, C.K. Owen, and K.D. Kohler. 2003. Thirty-sixth Annual Progress Report: 2002 Cropping Season. NMSU Agricultural Science Center at Farmington. Agricultural Experiment Station and Cooperative Extension Service. New Mexico State University. Las Cruces, New Mexico, USA. pp. 127-139.

O’Neill, Mick and Kevin Lombard. 2003. Hybrid poplar production under drip irrigation in the Four Corners region. In: O’Neill, M.K., R.N. Arnold, D. Smeal, T. Jim, C.K.

Owen, and K.D. Kohler. 2003. Thirty-sixth Annual Progress Report: 2002 Cropping Season. NMSU Agricultural Science Center at Farmington. Agricultural Experiment Station and Cooperative Extension Service. New Mexico State University. Las Cruces, New Mexico, USA. pp. 140-143.

E. Presentations

O’Neill, Mick, Kevin Lombard, Dan Smeal, and Rick Arnold. 2003. Hybrid poplar for the Four Corners region. NMSU College of Agriculture, Annual All College Conference. January 6-8, 2003. New Mexico State University. Las Cruces, New Mexico, USA.

O’Neill, Mick. 2003. Drip Irrigation. Seminar presented at the Nenahnezad Chapter House, Navajo Nation. March 13, 2003. Nenahnezad, NM.

O’Neill, Mick, John Mexal, and Kevin Lombard. 2003. Establishment of hybrid poplar under drip irrigation in the semi-arid Four Corners region. 8th North American Agroforestry Conference. June 23-25, 2003. Corvallis, Oregon, USA.

O’Neill, Mick. 2003. Overview of Oregon trip with particular attention on drip irrigation of hybrid poplar. Presentation to management of the Navajo Agricultural Products Industry. July 29, 2003. Farmington, NM.

O’Neill, Mick. 2003. Highlights of drip-irrigated hybrid poplar plantation. Briefing to management of the Navajo Agricultural Products Industry. August 14 & 18, 2003. Farmington, NM.

O’Neill, Mick. 2003. Highlights of drip-irrigated hybrid poplar plantation. Briefing to management of Western Excelsior, Inc. September 18, 2003. Farmington, NM.
F. Personnel Development

O’Neill, Mick and Renae Pablo. 2003. Visit to Potlatch Corporation Poplar Plantation. June 18-19, 2003. Boardman, OR.

O’Neill, Mick and Renae Pablo. 2003. Visit to OSU Malheur Experiment Station. June 19-21, 2003. Ontario, OR.

O’Neill, Mick and Renae Pablo. 2003. Attended the 8th North American Agroforestry Conference. June 22-25, 2003. Corvallis, OR.
 

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