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Submitted to: Crop Management at www.cropmanagement.org
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 12/17/2012 Publication Date: 1/22/2013 Citation: Sorensen, R.B., Butts, C.L., Lamb, M.C. 2013. Corn Yield Response to Deep Subsurface Drip Irrigation in the Southeast. Plant Management Network. doi:10.1094/CM-2013-0122-01-RS. Interpretive Summary: Corn production covers just over 300,000 ha in the tri-state area of Alabama, Florida, and Georgia with only 31% of these acres being irrigated (29). Of the total irrigated hectares in Georgia, only about 10% was irrigated using drip, trickle or micro-sprinkler while Florida, on the other hand, has over 220,000 ha using some type of drip or trickle irrigation (29). Due to drip system installation expense, it is assumed that most of these drip systems are on high value vegetable crops. It is unknown, if or how many, of these drip or trickle systems may be used to grow corn or other traditional row crops such as cotton or peanut. Economic simulations showed that subsurface drip irrigation (SSDI) would be more profitable for small areas (<30 ha) because of its lower investment per unit land area and lower pumping costs compared to center-pivot systems (2,21). Overhead sprinkler irrigation systems are the most common in the tri-state area, because they are easy to assemble, durable, do not require elaborate filtering systems, and familiarity with operation and maintenance. One major concern with overhead sprinkler systems is that once water exits an overhead sprinkler system, its fate may be affected by environmental conditions such that water may not reach the intended target but is lost due to wind and evaporation before it reaches the soil surface and becomes available for crop use. Thus, subsurface drip irrigation has the potential to provide consistently high water application efficiencies that could conserving soil, water, and energy. Some of the major benefits of drip irrigation include precise placement of water and chemicals, low labor requirements, and reduced runoff and erosion compared with overhead sprinkler type systems. These SSDI systems have the capability of frequently supplying water to the root zone thereby reducing the risk of cyclic water stress typical of other irrigation systems. Various researchers have shown that crop yield and quality can be increased using SSDI on tomato, (1,6), cotton (5,13), and corn (19,20,23). These SSDI systems are adaptable to various field sizes and shapes making them an important economic consideration, especially in the southeast. This economic advantage is further evident when considering the option to design a SSDI system to effectively cover an irregularly shaped field that would not be totally covered with a sprinkler type system (2). With proper SSDI designs, these systems can provide sufficient water to various parts of the field according to topography, soils series, or crop species. Drip tube laterals have been effectively installed at 0.2- and 0.3-m soil depths on cotton, corn, fruits, and vegetables (4,6,22,28). Drip laterals have been spaced at 1, 2, and 3 m apart with yields decreasing as lateral spacing increased to greater than 2 m (8,10,17,23). Drip tubing was buried or laid on the soil surface at various lateral spacings, i.e., every row or alternate row middles, in continuous cotton or cotton-corn-peanut rotations (7, 8, 9, 25). In continuous cotton with alternate row lateral spacing, there was year to year variability due to climatic patterns, but irrigated cotton yields were greater than nonirrigated yields especially in dry years (9). A comparison of alternate row versus every row lateral spacing showed no yield difference with either continuous cotton or cotton-corn-peanut rotation (7,8,25). With increasing concern for water conservation in the tri-state region (Alabama, Georgia, and Florida), the use of SSDI with greater irrigation efficiency may be of great interest to individual growers, water and environmental conservancy agencies, and policy making agencies. There is little long term corn yield response data with SSDI to make best management recommendations. Therefore, the objectives of this research were to determine the long-term yield response Technical Abstract: Long term grain corn (Zea mays L) yield with various crop rotations irrigated with subsurface drip irrigation (SSDI) is not known for southeast US. A subsurface drip irrigation system was installed on Tifton loamy sand with three crop rotations, two drip tube lateral spacings, and three irrigation levels. Crop rotations were alternate year, back-to-back, and three years between corn crops. Drip tube laterals were installed underneath each crop row (narrow) and alternate row middles (wide). Crops were irrigated daily at 100, 75 and 50% of estimated crop water use. Irrigation level affected corn yield 6 out of 8 years with 50% irrigation level having lower yield compared with 75 or 100% irrigation level. The 50% irrigation level averaged 7327 kg/ha while the 75 and 100% irrigation levels averaged 9512 kg/ha. The narrow lateral spacing increased corn grain yield 50% of the time but the higher yield may not offset the cost of the increased tubing compared with the wider lateral spacing. There is no clear evidence indicating one specific crop rotation better than another. Applying irrigation at 75% of recommended water use did not reduce crop yield implying a possible 25% water savings compared with full irrigation. |
