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

Abstract

A subsurface drip irrigation system with drip lines below alternating furrows was used toestablish three irrigation treatments designated as HW, MW, and LW applied 1.0*PET, 0.6*PET, and0.5*PET. By mid July a pattern of alternating rows with tall and short plants (row type) was visible. Astudy was initiated to quantify the variability of cotton growth and yield between adjacent rows. Theposition of irrigation laterals and flow rate of emitters was measured. Plant size and lint yield weremeasured in the two row types. The drip line moved closer to one of the adjacent beds as distanceincreased from the header line. Water flow was uniform among emitters along the drip lines. Plantheight decrease along the row was greater for short rows rather than tall rows. Cotton yields werehigher in tall rows than short rows. Short rows in all water levels had a decreasing yield trend withdistance from the header line. Tall row yields increased down the row in the LW and MW waterlevels, but decreased in the HW water level. Difference in plant height and yield between row typeswas attributed to water supply differences caused by drip lines being closer to tall rather than shortrows. The simultaneously decreasing trend of plant height in all water levels in both row types andHW treatment yield were likely caused by reductions in soil nutrient levels.