Cotton Production Response to Crop Row Offset and Orientation to SDI Laterals in the Texas High Plains

Abstract

Production questions concerning subsurface drip irrigation (SDI) lateral position and orientation to crop rows in the Texas High Plains have been asked. Field experiments were conducted at Halfway, TX to evaluate row to lateral offsets of 0.0, 0.13 m, 0.25 m, and 0.38 m; perpendicular crop row to SDI laterals with spacing at 0.76 m, 1.02 m, and 1.52 m; and crop row widths of 0.76 m and 1.02 m. Cotton rows spaced at 0.76 m resulted in generally higher yield than 1.02-m rows and significantly higher yields at the high irrigation level. There were significant differences in yields from individual rows of adjacent row pairs irrigated with a single lateral when row offsets were greater than 0.25 m on 0.76-m row spacing. However, cotton plants from rows closest to the lateral largely compensated for yield losses of rows farthest from the SDI lateral. The perpendicular compared to traditional row-to-lateral orientation resulted in declines in cotton lint yield and irrigation water use efficiency, with significant yield declines at high irrigation. Irrigation water use efficiency (IWUE) resulting from rows perpendicular to laterals followed yield trends with higher IWUE values in treatments with closer SDI lateral spacing. Orienting rows perpendicular across drip laterals using 0.76-m row widths resulted in significantly higher yields and IWUE’s than 1.02-m row widths at high irrigation capacity. These experiments will provide producers added information on how to install and manage existing SDI systems and whether to convert from traditional irrigation systems to SDI.