Horizontal Alignment of Drip Lines Relative to Beds in SDI: Effects on Cotton Growth and Yield

A subsurface drip irrigation system with drip lines below alternating furrows was used to establish three irrigation treatments designated as HW, MW, and LW applied 1.0*PET, 0.6*PET, and 0.5*PET. By mid July a pattern of alternating rows with tall and short plants (row type) was visible. A study was initiated to quantify the variability of cotton growth and yield between adjacent rows. The position of irrigation laterals and flow rate of emitters was measured. Plant size and lint yield were measured in the two row types. The drip line moved closer to one of the adjacent beds as distance increased from the header line. Water flow was uniform among emitters along the drip lines. Plant height decrease along the row was greater for short rows rather than tall rows. Cotton yields were higher in tall rows than short rows. Short rows in all water levels had a decreasing yield trend with distance from the header line. Tall row yields increased down the row in the LW and MW water levels, but decreased in the HW water level. Difference in plant height and yield between row types was attributed to water supply differences caused by drip lines being closer to tall rather than short rows. The simultaneously decreasing trend of plant height in all water levels in both row types and HW treatment yield were likely caused by reductions in soil nutrient levels.