Management of Sorghum Under Limited Irrigation1

Abstract

AbstractGrain sorghum [Sorghum blcolor(L.) Moench] is produced with furrow irrigation across much of the semiarid West. Rising energy costs and declining water supplies in some regions have caused many farmers to irrigate with less water than required for maximum yield. Irrigation needs could be reduced if rainfall were used effectively on irrigated land. Research was done at the Texas Agric. Exp. Stn.. Etter, TX from 1979 to 1982 to compare different systems for limited irrigation of sorghum while attempting to maximize the use of rainfall. The study was conducted on graded furrows (0.3% slope) on a fine, mixed, mesic Torrertic Paleustoll (Sherm silty clay loam soil). The irrigation treatments were: 0, 2.5, 3.8, 5.1, and 10.1 (full irrigation) cm applied at each irrigation. The treatment receiving 2.5 cm was irrigated only in every third furrow and the treatment receiving 3.8 cm was irrigated in alternate furrows. All limited irrigation treatments contained furrow dams spaced 3 m apart. Total water applied varied with years due to rainfall. The seeding rate was varied down the row on plots that received 2.5, 3.8, and 5.1 cm per irrigation. Variable seeding rate was compared with uniform seeding on the 3.8 cm water treatment. Every third row was left blank on the 2.5 cm water treatment. Limited irrigation reduced runoff compared to full irrigation. Water advanced further down the field in alternate than in every furrow irrigation. The dams of non‐irrigated furrows were left in better condition to retain water from precipitation than in the irrigated furrows. The irrigation water use efficiency of 3.8 cm applied to alternate furrows was higher than 5.1 cm applied to every furrow with no change in yield. The yield and water use efficiencies from plots with uniform seeding rate were equal to those from variable seeding rate plots