Submitted to: Peanut Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/15/2006
Publication Date: 3/15/2007
Citation: Sorensen, R.B., Nuti, R.C., Lamb, M.C. 2007. Rodent management for surface drip irrigation tubing in corn, cotton, and peanut. Peanut Science. 34:32-37
Interpretive Summary: Surface drip (SD) irrigation has been widely used on vegetable crops and has recently been gaining interest in field crop production. Damage of the drip tubing from rodents has been identified as a major concern for SD adoption in field crops such as corn, cotton, and peanut. Research was conduction at 4 sites in southwest Georgia to document the cost associated with SD repair and possible physical or chemical management techniques to reduce rodent damage. Site 1 had a slight cover of soil and debris over the tubing (no chemicals were applied); Site 2 had the an insecticide and an animal repellent applied; Site 3 had 5 chemicals applied along with three drip tubing thicknesses (8, 10 and 15 mil); Site 4 had the animal repellent. All sites had a control where SD tubing was laid on the surface for control. Rodent damage was minimal in corn and cotton. Rodents have a large number of predators and need cover to survive. Corn and cotton have very little crop cover for rodents to hide for protection during the growing season compared with peanut. Most rodent damage was in peanut where there is abundant crop cover along with food and water. All four sites were used to determine the cost required to repair one hole. It was shown that it costs about $0.67/hole with the major cost attributed to labor or about 78% of the total cost. The breakeven point of when to fix versus when to replace would be about 200 holes/ac depending on labor and tubing costs. At Site 1, strip tillage and stalk pulling equipment slightly buried SD drip tubing. This cover protected the tubing during the next couple of years to raise cotton, corn and peanut. There was minimal damage to the tubing. Overall at this site there was a total of 20 holes repair of which 10 were caused by mechanical not biological damage. This was an average of 3 holes/ac per year. Chemical management included two insecticides, one rodenticide, and one repellent. These chemicals were applied just prior to canopy closure. At Sites 2, 3, and 4 there was no difference between the control and chemicals applied with respect to rodent damage. However, at Site 3, there were over three times more holes in the 15 mil tubing compared with the 8 mil tubing. Rats and mice have incisors that need to be sharpened. They also have the tendency to chew to exercise their jaw muscles and possibly to relieve nervousness. The drip tubing that was slightly buried had the best rodent control (5 holes/ha) compared with all other treatments (717 holes/ac). This implies that lightly burying the tubing may be the only option available to reduce rodent damage in peanut fields. However, this light soil cover on the drip tubing may not be an option if clean tillage is the normal farm practice such that drip tubing would need to be destroyed and replaced each year. If the tubing could be installed and not removed for three to four years such as with strip tillage, this system would be a more cost effective irrigation system for installation and repairs.
Technical Abstract: Surface drip (SD) irrigation of field crops has been gaining interest in the farming community. However, rodent damage is one of the major drawbacks for SD acceptance. This research documents the cost of repairing drip tubing and effectiveness of several rodent control methods. Four sites were used to identify cost of repairing tubing. Treatments included drip tubing on the soil surface with no treatment, tubing that was lightly buried, sprayed with an insecticide or animal repellent, and edible rodenticide placed next to the tubing. Once a leak was found, it took an average 4 minutes to repair the hole. Each repair had an average cost of $0.67 for labor and repair materials. This does not include time or transportation cost to find the leak. Rodent damage was the same in the control versus any chemical management technique. At Site 4, the animal repellent, Ropel®, did have less rodent damage (2392 holes/ha) compared with the control (6049 holes/ha) however, the damage was extensive enough that it would be more cost effective to replace the tubing than to repair. The drip tubing that was slightly buried had the best rodent control (5 holes/ha) compared with all other treatments (1771 holes/ha). One disadvantage of burying the drip tubing is removal. Strip tillage along with burying the drip tubing showed excellent resistance to rodent damage and appears to be a cost effective management tool for SD.