Submitted to: ASAE Annual International Meeting
Publication Type: Proceedings
Publication Acceptance Date: 8/1/2004
Publication Date: 8/5/2004
Citation: Wanjura, D.F., Mcmichael, B.L., Upchurch, D.R. 2004. Horizontal allignment of drip lines relaive to beds in sdi: effects on cotton growth and yield [abstract]. ASAE Annual International Meeting. Paper No. 041050. p. 1-13. Interpretive Summary: Subsurface drip irrigation (SDI) use is increasing because of the potential for more efficient use of water and the capability to irrigate with lower water quantities. The positive aspects of system performance and crop yield increase are offset by high initial system costs and the requirements of greater precision in water application. During the second year after installing an SDI system with drip lines placed under alternating furrows a pattern of uneven cotton growth was observed between adjacent rows across a field in late July. A study was initiated to quantify the variability of cotton growth and yield between adjacent rows, the horizontal position of irrigation laterals relative to plant rows was measured and the flow rate of single emitters was sampled. The drip line position was closer to one of the adjacent rows as distance increased from the header line. Water flow was uniform among emitters along drip lines. Difference in plant height and yield between adjacent rows was attributed to water supply differences caused by the position of drip lines. The importance of equidistant horizontal spacing relative to both plant rows irrigated by a single drip line was demonstrated by the results of this study.
Technical Abstract: 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 100%, 60%, and 50% of reference evapotranspiration. 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.