Irrigation Water Conservation Using Wide-spaced Furrows 1

Furrow irrigation studies comparing water applications to narrow and wide-spaced furrows were conducted on three crops at thee locations in Oklahoma over eight growing seasons. Wide-spaced-furrow irrigation usually required about half the water of narrow spacing. In 9 of 11 studies, no yield reductions were noted. In the seasons where yield reductions were noted, the atmospheric evaporative demand was high. A simple test was devised to indicate if a season in progress shows high atmospheric demand. The evaporative demand test involves measurement of rainfall and daily wind movement. Using standard National Weather Service instruments, daily average of rain > 1.6 mm between 15 July and 31 Aug. combined with daily wind movement < 155 km in August caused no yield reduction in wide-spaced-furrow irrigation. Wind was measured at the standard height of a “Class A” evaporation pan (51 cm). Conservation of water from wide-spaced-furrow irrigation should be possible on medium to fine textured soils in many semiarid regions of the world