Location: National Peanut Research LaboratoryTitle: Yield response and economics of shallow subsurface drip irrigation systems
Submitted to: Journal of Agricultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/25/2016
Publication Date: 9/30/2016
Citation: Sorensen, R.B., Lamb, M.C., Butts, C.L. 2016. Yield response and economics of shallow subsurface drip irrigation systems. Journal of Agricultural Science. 4(1):1-11.
Interpretive Summary: Drip irrigation due to its simplicity of design, has been used to irrigate vegetables and high value crops for many years. Previous research has shown that shallow subsurface drip irrigation (S3DI) can be installed easily with low initial investment and provide flexible irrigation schedules. The yield potential for S3DI was over 2, 3, and 7 times greater than nonirrigated crops of peanut, cotton, and corn, respectively. Strip tillage, a form of conservation tillage that disturbs a small strip of land where the crop is planted, can be an effective management tool to reduce crop production expenses. However, the acceptance of strip tillage has been slow due to grower concerns of increased plant/soil born diseases and ultimately loss of yield. With the use of strip tillage combined with S3DI thereby leaving the drip tubing in the field for a minimum of three years, may be quite economical, and could therefore be used on small irregular shaped fields. The objectives of this research were to determine: 1) crop yield and associate net returns over drip system expenses for the life of the drip tubing, 2) yield comparison of irrigated to nonirrigated treatments, and 3) the susceptibility of shallow buried drip tubing to biological or mechanical damage. The field for this research was 54 ft wide by 1100 ft long. Crop rotation was cotton, corn, and peanut with only one crop being planted each year. Drip tubing was installed in cotton and left in the field for three cropping seasons and removed prior to peanut harvest. Irrigation events for peanut, cotton, and corn were determined by IrrigatorPro and verified using water potential sensors installed at 12-inch soil depth and monitored twice per week. The recommended maximum field length with 90% emission uniformity was about 750 ft. The total field length was 1100 ft or about 300 ft longer than recommended for this tubing diameter. This would allow an irrigation variable within the field. Net revenue was determined by subtracting the expense of the drip system from the gross revenue of the total crop value for the life of the drip tubing installed. Replications for yield and irrigation treatments were not randomized so analysis of variance statistical analysis was not valid. Therefore, a one-sample T-test was used to determine if the irrigated crop yield by down-row distance was different from the average non-irrigated yield within the same year. Precipitation was greater in 2003, 2004 and 2005 compared with the last three years of the project. A one-way T-test comparing irrigated to nonirrigated net revenue for the life of the project show the 95% confidence interval for net revenue between $2213 and $2934 ac-1 (p<0.001). Since the total net revenue for nonirrigation was only $1497 ac-1 which is far below the lower confidence interval, then installation of drip irrigation for these six years with the various rotations was economically beneficial. Total repair cost for the first three years was just over $3.24 ac-1 yr-1. Damage to the tubing caused by biological activity was minimal. Mechanical damage was paramount due to the lack of an electronic guidance system. This S3DI system requires the need for strip or no-tillage type operations. Growers would need an electronic guidance system to keep equipment on track. More information is needed for other growing areas with different management styles and irrigation system designs to determine drip tubing length of service before it must be removed due to the expense of maintenance to repair leaks or emitter plugging. Currently, there is no equipment manufacturing company in the local area that promotes equipment to install or remove drip tubing from the field. The ARS-USDA-National Peanut Research Laboratory is currently working on equipment that may be manufactured from existing equipment that can be used to install and extract drip tubi
Technical Abstract: Field tests were conducted using shallow subsurface drip irrigation (S3DI) on cotton (Gossypium hirsutum, L.), corn (Zea mays, L.), and peanut (Arachis hypogeae, L.) in rotation to investigate yield potential and economic sustainability of this irrigation system technique over a six year period. Drip tubing was installed every three years in alternate row middles, strip tillage was used prior to planting, and tubing was removed prior to peanut harvest. The installed system cost about $422 ha-1 for tubing and flexible mainline. Irrigated crop yields were increased five out of six years and net revenue four out of six years compared with nonirrigation. Total irrigated net revenue over six years was almost double ($6358 ha-1) compared with nonirrigated net revenue ($3700 ha-1). Drip tubing repair expense for 2003 to 2006 was just over $8 ha-1 yr-1. This type of irrigation system seems to be economical for this soil type, crop rotation, and management/tillage techniques. However, more information is needed when using S3DI in other growing areas, soil series, crop rotations, and management styles.