Subsurface Drip Irrigation Research Not Final, but Insightful
Farmers interested in irrigating using Subsurface Drip Irrigation (SDI) in Delaware now have some state-specific “scenarios” to consider thanks to research being done through University of Delaware (UD) Cooperative Extension. Earlier this winter, 29.5 miles of SDI lines were buried at 16” deep and placed 60” apart throughout the UD Warrington Research Farm to test various production scenarios.
In May 2012, UD Extension agent James Adkins and staff planted 18 acres of corn and soybeans over the SDI field. Corn was planted in row patterns that straddled the drip tape (15” between tape and row center) or lined up directly on top of the drip tape. Soybeans were planted across the field in 7.5” rows without regard to the drip line placement. As soil moisture measurement is critical for drip, plots were irrigated using weather station evapotranspiration (ET) data, or based on soil moisture measurements at varying depths in the soil profile. Visual differences were evident almost immediately between the various irrigation treatments; however, the yield data has yet to be statistically analyzed.
Funding for this multi-year SDI research project was provided through the USDA Natural Resources Conservation Service (NRCS), the Delaware Department of Ag, and other agricultural partners to determine effectiveness of SDI systems in Delaware. Although definitive results of the research cannot be determined from one year of harvest, the first year’s study brought to surface the following:
Subsurface Drip irrigation is more challenging to manage in sandy soil than silt/clay-based soil, as the capillary action of heavier soils draw up more water up vertically;
Tape is susceptible to insects (injection of pesticide through the drip lines may be required to prevent insect damage);
Ground must be wet prior to planting—use drip tape to continue to water plants. When using drip tape on sandy soils, it is extremely hard or almost impossible to get the soil wet once it is dry;
SDI requires a high level of management (ex: Periodic flushes of the system are needed to keep tape from filling with precipitates);
Drip tape uses less electricity, but not necessarily less water than a pivot system.
More information on SDI will be available as research continues. For background information on this SDI project, please visit www.de.nrcs.usda.gov/technical/engineering/.
Caption: UD Extension Agent James Adkins provides NRCS employees with an interactive tour to highlight first-year experiences with SDI.
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