Bryan Wilkins

Pecan Irrigation-and the irrigation system installation at

the GCREC

In South Alabama we generally get enough rain in June and July to size our pecans.

We don’t get enough steady rainfall during the critical August and September nut filling period to adequately fill the nuts out.

Irrigation can make up the difference.

Why Irrigate????

Gives the best use of the available water supply by controlling the water flow to give maximum yields with the least amount of waste.

Evaporation loss minimal because the water it applied below the soil surface

Low pressure requirements=lower operating costs

Lower labor requirementsIrrigation can be applied anytimeFertilizer can be injected through the system

Advantages of Drip Irrigation

Less disease and insect pressure Less wetted area means less weeds and restricts

populations of potential pest hosts No wind effect, lets you irrigate around the clock

It’s a permanent systemEasily and readily adapted to automatic controlsProvides improved infiltration in soils with low intake

capacityAllows for the use of more saline water.

Advantages of Drip Irrigation

Pecans have a very efficient water transport systemDeveloped ability to avoid stomatal closure under

high temps with adequate waterPecans are very inefficient users of waterRequire large amounts of water to support optimal

growth and fruit production

Pecans and Water

You must have a clean water supply. Adequate and dependable filtering systems are difficult to provide

Clogged emitters that result from poor water filtration, algae, bacteria, sulfur, iron and calcium in the water.

Non-uniformity of water discharged from the emitters.On sandy soils water is not evenly distributed , the water

does not tend to move laterally causing insufficient root volume wetting and leaching of nutrients.

Mice and rabbits and other animals cause damage by chewing on the flexible lines.

Disadvantages of Drip Irrigation

Increased Nut Size/Quality, Nut Retention

Minimizes Shuck Decline/Sticktights

Enhances shuck splitReduces Severity of

alternate bearingAbility to inject

fertilizer and systemic insecticides

Other Advantages of Irrigation

Adequate nut fill requires late season water

1 acre inch x 27,154 gallons/acre inch x 7 days = 3,879 gallons/acre/year

Extension Recommendation is 1 to 2 inches/week

3,879 gallons27 trees/acre

2 acre inches = 288 gallons/tree/day

= 144 gallons/tree/day

55 Acre Inches – Growing SeasonMarch 5”April 4”May 4”June 4”July 10”August 10”September 10”October 8”

TOTAL 55”

Dormant Season Irrigation

Mid-November 2”End December 2”First February 2”

Water about every 6 weeks

TOTAL 6”

4” Well pumping 85 gallons/minuteWater Source

Installed August 2012Drip Irrigation

components:drip tube with ½ gph inline

emitters spaced 3 feet apart

2 lines per tree plowed in at the edge of the herbicide strip

Irrigation at GCREC

Cost of System:Parts and Labor: $700/AcreWell: 4 inch 5 HP $6200.00

The system is a continuous loop, live feed system. It has a 2” main feed line running through the center

of the orchard. 1½” lines on the end of the rows supplying water.All drip lines are plugged connected to the main feed

and the lines on the end of the row.This creates a continuous water supply that keeps

the pressure up and waters more effectively all the way down the row.

Irrigation System Design

A siphon valve is installed to put acid and chlorine through the system periodically

Acid will clean any mineral deposits that may block the emitters and chlorine will take care of algae and bacterial slime

System Maintenance

2 Treatments: Irrigated and non-irrigated5 Replications3 Tree plots with the center tree being the

record treeNon irrigated trees have the water shut off with

ball valves

Irrigation Experiment

Data to be collected:Date of shuck splitHarvest datePercent of shuck tightsPercent KernelTotal Yield

Irrigation Experiment

QUESTIONS