At Woolf Enterprises in Huron, Calif., 2008 cotton acreage will fall to 2,300 acres, a 75 percent plus reduction from the 10,000 acres planted just six years ago. The major reason is the limited supply and increasing costs of water, and the competition for acreage from newly planted almond and pistachio orchards, plus wine grape vineyards.
Woolf's Crop Production Manager Kevin Lehar said the operation has sought innovative ways to maintain a cotton mix. Drip irrigation is a method now reaping dividends.
“Many farmers look at the return per dollar invested. Because of where our operation sits, we base our operation on the return per acre-foot invested because water is such a precious resource for us,” Lehar said. “We are primarily in the old priority two area (of the Westlands Water District) so our water availability is not as good as some of the guys on the east side of the canal.”
Water-related costs (water plus conveyance systems and irrigation-related labor) comprise 40 percent to 50 percent of the cost of growing cotton. He called water the highest cost input on any crop grown at Woolf's.
Speaking to cotton growers at the Central Coast Cotton Conference in late November in Monterey, Calif., Lehar discussed the issues challenging cotton's viability, not only water but higher costs for diesel fuel, natural gas, labor, and worker's compensation insurance. He said the last minimum wage increase cost Woolf $500,000 annually.
The initial costs of drip irrigation systems are pricey but the rewards come down the pike. After experimenting with drip on a small basis over the last five years, it's now in use on about 7,000 acres at Woolf.
“We had to spread the costs over more acres and looked at multiple crops over multiple years to spread the costs around. The longer the equipment is working and viable, it will last multiple years,” said Lehar. “When you can spread drip system costs over five years instead of three, simple math indicates you are money ahead.”
The first option for moving systems was looking at furrow or surface drip. Lehar explained the use of drip in garlic fields. “The irrigation tape is installed after fall planting. Due to crop rotation, more surface drip is used than buried drip. We lay the tape across the top and we irrigate it that way. We have done some work with buried drip in a 40-inch bed and used that as a rotation with cotton.”
Once the garlic crop reaches maturity usually in June, the water is turned off. The drip tape is moved to another field, either a 40-inch cotton system or a 60-inch tomato system both with in-furrow drip.
An advantage of the drip system is allowing the grower to take the crop full season. Lehar noted, “Typically with processing tomatoes first color on the fruit leads to cutting off the overhead irrigation to eliminate disease problems. With drip irrigation, the crop can run full season.”
One of the problems with conventional irrigation in cotton, especially Pima, was moving sprinklers amid the plant's spreading branches. “It's hard to get people to move pipe,” he said. “We normally get to the point where we can't afford to continue to move pipe so we shut the water off. With drip, you can take cotton to full season.”
The portability of the drip system is essential. It must be moved quickly from one field to the next.
Lehar said, “When we started this program, we hit some bumps but now our guys have been doing this for about five years. They can actually take a field down, move it, and get it fired back up within three days. They have it down to a science.” Experience has led to efficiency. Drip tape removal costs in the beginning cost about $75 per acre. It's now at $30.
Woolf employees built their own removal system even though commercial equipment is available. “We think we build a better mousetrap,” Lehar noted.
Some of the drip systems are now two-years-old. The plan is five years of use with rotation. Mostly 8-mil tape is used.
“While 15-mil tape could be used, our philosophy is after five years we'll have some compaction issues so we'll need to get in there and work the ground,” Lehar said. “In addition, water short years mean we have to pump water from the 35 wells on the ranch. Because of high salt and TDS (total dissolved solids) levels in the well water, fields need to be worked up and soil amendments added.”
Lehar said drip irrigation provides 90 percent to 95 percent water efficiency. The beauty is the same amount of water is delivered from the source point to the end of the field. Under or over irrigation by conventional irrigation is eliminated.
Distributing fertilizer through a drip is also a plus. “If you're over-irrigating a head end through conventional irrigation, then you're over fertilizing the head end. With the drip system, you know what each emitter is releasing.”
Woolf's goal is 100 percent drip on 60-inch tomato beds and 30-inch cotton beds. Lehar said that success depends on the companies for which Woolf grows garlic and onions.
Cotton works well in the Woolfs' mix mostly as a rotation with tomatoes. Tomatoes repeatedly grown on the same ground leads to increased disease pressures, more weeds, and decreased yields decrease. He said cotton works well in the rotation more than anything else.
Drip has not yet lead to large yield increases or huge water savings yet, but Lehar is optimistic. “This year my drip fields out yielded any of the conventionally irrigated fields. I attribute that specifically to irrigating more efficiently with the drip system.”
Weed pressure has declined about 50 percent with drip irrigation, Lehar noted.
The cost of a drip irrigation system varies across the board and is dependent on various factors. Mike Pitter, branch manager for Rain for Rent in Chandler, Ariz., said $750-$1,500 per acre is the average cost, including a filtration system, booster pump, underground PVC, risers, drip tape, valving and installation. About one-third of the cost is for installation.