The SARE-funded project had these objectives:
1. Evaluate the long-term effects of subsurface drip irrigation on permanent crops such as pecan trees
2. Compare irrigation management of subsurface drip irrigation with other irrigation systems
3. Evaluate energy and water savings
In addition, the USDA Agricultural Research Service, through its National Pecan Advanced Cloning Testing System, has these goals:
1. Identify which rootstock is best suited for this climate
2. Determine if pecan is a viable alternative crop for small land users in this area
3. Determine which varieties of pecans are best adapted to the Tucumcari area, the plains of Texas and northern parts of USDA Zone 6
Growing pecan trees in northeastern New Mexico is a challenge because of its late spring frost and distinctive soils. This project expands on a 15-year National Pecan Advanced Clone Testing System research project, in which project coordinator Lem Chesher is a participant, to determine which pecan rootstocks and scion clones are best adapted to the area. Chesher’s plan is to assess subsurface drip irrigation on permanent crops like pecans.
A subsurface drip system was installed in February 2002 and the trees planted in March. Despite unusually dry conditions, the pecan test plot performed well, with all trees surviving and adding 6 to 12 inches of growth. And they did it using 25% less water than with the traditional micro-sprinkler system.
The summer of 2002 was one of the driest on record in the research area. Farmers who irrigate with canal water were allotted only 3 acre-inches of water, and many wells went dry or were drawn down severely. Still, the 80 pecan trees in the test plot survived and added 6 to 12 inches of new growth.
During the season, the soil surface remained dry, but soil below the surface was kept at 50% moisture with irrigation of 0.25 to 0.5 inches of water every three or four days. Few weeds grew to compete for water until a mid July storm dropped an inch of moisture. To control the weeds, sweeps were used between the rows and Roundup was used near the tree base. The well water was treated with nitric acid to reduce the pH to 6.5 from 8, and zinc was foliar sprayed four times.
The subsurface drip system used about 25% less water than the micro-sprinklers typically used. Project coordinator Chesher says the savings should increase this year as the producer learns how to use the system more efficiently, engaging the daily evapotranspiration rates for pecans provided by USDA-ARS in Bushland, Texas.
“If the test plots had been irrigated with canal water, I do not think the trees would have survived the summer on the 3 acre-inches of water allotted,” says Chesher. “There was no water left in the canal after June.” Further, winds prevented running the micro-sprinklers on many days, and the sprinklers irrigate 95% of the orchard floor compared with only to the tree line with the drip system.
Tree calipers were to be taken in February 2003 for comparison and provided to USDA-ARS in March for their research on pecan rootstock.
BENEFITS OR IMPACTS ON AGRICULTURE
Homeowners and small landholders – 5 to 20 acres – have increased their planting of pecan trees. The sale of trees through the local soil and water conservation district rose 60% in 2002 from 1999, mainly to homeowners using drip irrigation.
Project coordinator Lesher says he’s unable to estimate the amount of water saved, but he says that local small farmers in five to eight years should be able to generate added income from pecan sales along Interstate 40.
“The subsurface drip irrigation is very new to this area,” says Chesher. There is still a wait-and-see attitude right now, but we have several outreach programs planned for 2003 and 2004.”
FARMER ADOPTION AND DIRECT IMPACT
Chesher anticipates that tree sales will rise again in 2003, assuming there are enough trees to meet demand. He hopes to increase outreach to recommend that potential growers purchase new USDA releases like Pawnee and Kanza instead of Western and Wichita, varieties not well suited to the area.
While he received only a few written comments, Lesher says producers tell him they are amazed at the lush green trees growing on what appeared to be little or no water. He says he planted a few seeds of watermelon and cantaloupe over one of the drip lines, which added to the effect of lush, green growth.
“This stirred many questions because most area crops were dead or dying because of the drought,” he says. “The water saving and efficiency were evident.”
FUTURE RECOMMENDATIONS OR NEW HYPOTHESES
None were made.
DISSEMINATION OF FINDINGS
The research project was discussed at several venues, including these:
· 3rd National Pecan Scientists Workshop, Las Cruces, June 2000
· Western Pecan Conference, Las Cruces, March 2001
· Canadian River Soil and water Conservation District annual meeting, Tucumcari, November 2001
· Crop Germplasm Committee for Pecans and Hickories, Las Cruces, March 2002
· Canadian River Soil and Water Conservation District meeting, Tucumcari, May 2002
· Tucumcari Tree Board meeting, Tucumcari, June 2002