Removing peanut foliage adjacent shallow subsurface drip laterals to reduce rodent damage

Authors: Sorensen, Ronald - Ron

Submitted to: Crop, Forage & Turfgrass Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/30/2019
Publication Date: 8/8/2019
Citation: Sorensen, R.B. 2019. Removing peanut foliage adjacent shallow subsurface drip laterals to reduce rodent damage. Crop, Forage & Turfgrass Management. 5:190010. https://doi.org/10.2134/cftm2019.01.0010.
DOI: https://doi.org/10.2134/cftm2019.01.0010

Interpretive Summary: The use of shallow subsurface drip irrigation (S3DI) in field crops has been quite successful. Drip tubing was left in the field for five years with a cotton-corn-corn-corn-peanut rotation. This research showed that for tube longevity, conventionally tilled areas had less tube repairs compared with strip- or no-tilled practices. Thinner wall tubing (8 mil) had 3.5 times more holes compared with thicker wall tubing (15 mil). The “cost-to-repair” versus “cost-to-replace” tubing indicates average replacement time at about 5.4 years. Both corn and cotton have an open type canopy such that rodents cannot hide from predators quite as easily as with a closed canopy such as peanut. Previous research has shown that buried drip tube laterals had less damage by rodents in corn and cotton compared with peanut. This implies that a closed canopy type crop (peanuts) would have more rodent damage than an open canopy type crop (corn or cotton). It would seem reasonable that removing peanut foliage adjacent the shallow buried drip tubing would result in a semi-open canopy and would reduce rodent damage. With the open gap associated with the drip lateral, these animals will probably not move into this open space, thereby reducing the “opportunity time” for the rodent to find and chew on the tubing. However, reducing peanut foliage could reduce peanut yield. Therefore, cutting a small portion of the total plant leaf area of peanut foliage adjacent drip tube laterals should create an open type canopy but not reduce pod yield. Therefore, the objectives of this research were to determine if removing small amounts of peanut foliage affected peanut yield and if the open type canopy could reduce rodent damage on shallow subsurface drip tube laterals. This project was conducted from 2015 to 2018. Treatments consisted of 8 and 16-in cut gap in alternate row middles, 8 and 16-in cut gap in all row middles, and a no-cut control treatment. In 2015 only, there was one treatment added to remove about 70% of the total forage. The cutting treatments consisted of two cutting coulters spaced 4-in adjacent each drip tubing for the 8-in gap in alternate row middles. The coulters would be moved to 8-in distance adjacent each drip tube in alternate row middles for a 16-in gap. Coulters were added and removed to the tool bar to cut peanut branches in all row middles or alternate row middles to have the same 8- and 16-in gap. Each treatment was replicated a minimum of three times. Peanut foliage/branches were cut at about 90 days after planting depending on plant growth. The objective was to keep peanut branches from over-lapping and covering the area above the buried drip tubing. After each plot was cut, the total foliage mass from a 10-ft length in each cut middle was collected, dried, and weighed. The total yearly percentage foliage removed was determined by totaling the total mass of material cut from the middle of the rows divided by the total mass removed prior to harvest. Prior to each harvest, three random areas of 3-ft by 6-ft of peanut row were cut to the soil surface to determine the total mass of plant material available. The dry mass from each cutting and each treatment was totaled to determine the total mass of peanut hay removed during the growing season. Peanut was dug with a 2-row inverter. After field drying, peanuts were combined using a 2-row combine with a bag attachment. The total mass was recorded. Moisture samples were collected, and all samples were dried below 10.5% moisture. Subsamples were sent for an official grade. S3DI systems were installed each year so that new tubing would always be evaluated. Irrigation events for the sprinkler systems were scheduled using IrrigatorPro for peanut and verified with soil water potential sensors. Irrigation events for S3DI were scheduled using soil water potential sensors installed at 10 and 20-in soil d

Technical Abstract: Using shallow subsurface drip irrigation (S3DI) in field crops has been successful from a yield and economic standpoint. However, the use of S3DI in peanut has been discouraging due to the amount of rodent damage to drip tubing. The objective was to determine if cutting peanut foliage adjacent the drip tube lateral would reduce rodent damage. Peanut foliage was cut 90 days after planting using coulters to cut 8- and 16-inch gaps adjacent drip tube laterals. Multiple cuts were needed to keep peanut branches from over-lapping the drip tubing. Total foliage mass removed from cut middles was determined. Removed foliage mass was totaled and percentage removed per total available was calculated. Peanut was harvested, and yield and grade characteristics were determined using normal procedures. After harvest, drip tubing in each plot was manually extracted and evaluated for biological damage. There was no difference in the amount of foliage removed between the 8- and 16-in cut gap. The average amount of foliage removed with either gap space was about 16% of the total forage available. There was no yield or grade difference with cut gap width. There was twice as many holes in the control and 8-in gap compared with the 16-in gap such that rodent damage decreased as cut gap increased. This implies that within a peanut crop, foliage can be removed adjacent the S3DI drip laterals to reduce rodent damage without loss of peanut yield or grade.