ECONOMIC ANALYSIS OF SUBSURFACE DRIP IRRIGATION LATERAL SPACING AND INSTALLATION DEPTH FOR COTTON

Abstract

Cotton lint yield, seed mass, fiber quality parameters, gross return, and net return were compared for subsurfacedrip irrigation (SDI) lateral spacing and installation depth in a clay loam soil in western Texas for three seasons. Drip lateralswere spaced either in alternate furrows (2 m) or beneath every planted bed (1 m), and installation depths were either 0.2 or0.3 m beneath the soil surface. Net return was gross return minus fixed and variable costs. Fixed costs included the annualpayment for financing the initial investment of SDI materials and installation (5.00% interest over 10 years), the annual landlease, and the annual depreciation of the SDI system. Variable costs were those associated with cotton production and weresimilar for the two drip lateral spacings. Lint yield, seed mass, and gross and net returns were significantly greater for the1 m lateral spacing in the first two seasons, but these parameters were significantly greater for the 2 m lateral spacing in thethird season. These parameters were consistently greater (either numerically or significantly) for the 0.3 m lateral depth inall seasons. Most fiber quality parameters were not significantly different, and no consistent trends were observed. Lint yieldsranged from 640 to 1,635 kg ha-1, and net returns ranged from -$395 to $1,005 ha-1. The low lint yield and resulting net losswere due to a germination failure in the second season for the alternate furrow spaced laterals. Additional seasons of studyare required before conclusions might be drawn concerning the most economic lateral spacing for cotton production in theTrans-Pecos region of Texas, but the 0.3 m lateral depth resulted in greater net returns than the 0.2 m lateral depth.