Large-Scale Field Trials: The Design
Blake Sanden, Louise Ferguson, Craig Kallsen, Brian Marsh & Bob Hutmacher
Using Saline Ground Water for Irrigation
Counting on the salt tolerance of cotton and pistachios, a San Joaquin Valley grower (Kern Co., California) started pumping brackish groundwater for an experimental drip tape field in cotton in 2003, with the intent of interplanting pistachios in the following years. We used this opportunity to undertake a large-scale field trial to to test the use of saline water for commercial-scale production and the development of a new pistachio orchard. Of particular interest to use was the opportunity to evaluate the orchard under an irrigation system which uses shallow sub-surface drip tape (SDI).
Starting in 2004, twelve 19.5 acre test plots were set up in a randomized complete block design in two adjacent parcels. With each plot being nearly 20 acres in size, the 240 acres dedicated to this trial is possibly the largest replicated salinity irrigation test ever attempted in the San Joaquin Valley.
|Spring 2004||Field planted to pima cotton|
|March 2005||Pistachio Pioneer Gold (PG1) rootstocks planted to an 18 x 22 foot spacing, inter-planted with four rows of pima cotton. A set of 10 trees in the middle of each 19.5 acre plot, along with the adjacent cotton used for intensive sampling. A total of 23 pistachio UCB rootstocks planted adjacent to these areas.|
|August 2005||Pistachios budded with a Kerman scion|
|Spring 2006||Four rows of pima interplanted with pistachio rows
|Spring 2007||Cotton interplanting cancelled due to a 40% reduction of district water: grower canceled entire Westside cotton program|
The irrigation system used drip tape with emitters every 12 inches, installed at about 10 inches below field grade.This system was designed for a final tree
spacing of 22 feet.
In this system, the cotton received 1.99 inches/day and the pistachios received 0.57 inches/day, with irrigations are scheduled for a 24 hour duration due to restrictions on canal water delivery.