Comparison of Subsurface Drip Irrigation Uniformity Designs on Cotton Production

Abstract

Relaxing subsurface drip irrigation (SDI) uniformity design standards for systems irrigatingcotton in semi-arid environments could reduce installation costs. A SDI system was installed andcotton production experiment conducted from 2001 to 2005 to evaluate good, acceptable, and poorirrigation uniformity (FV = 7.5, 15.7, and 37.1%) at moderate and near full irrigation levels (0.6BI and1.0BI). Flow variation treatments were established by installing drip laterals in separate zones withlateral diameters of 22, 25, and 17 mm and pressurizing corresponding laterals at 83, 45, and 69 kPain very good (VGD), acceptable (ACC), and poor (POOR) treatment areas.<br><br>Cotton yield response tended to follow changes in emitter flow rate along the length of drip laterals,but not to the extent expected. Total cotton lint yield and total yield value within a treatment areawere not significantly affected by irrigation system designs with flow rate variations (FVs) between7.5 and 37.1 during the four test years. Average total lint yields were in a narrow range between1442 and 1490 kg ha-1 yr-1and average yield values were between 1681 and 1749 $ ha-1 yr-1 amongall treatments. Conditions other than SDI design, common to the Texas High Plains, impacted cottonyield variability.