A Comparison of Sprinkler and Flood Irrigation for Rice 1

Sprinkler irrigation of rice ( Oryza sativa L.) has recently been considered to reduce water use and increase grower flexibility in U.S. production areas where flood irrigation is predominant. Tests were conducted for 2 yr on a Sharkey clay (Vertic Haplaquept) to evaluate selected rice cultivars under sprinkler vs. flood irrigation. Irrigation methods were main plots and three cultivars in 1983 and six cultivars in 1984 were subplots. Sub‐subplots in 1984 were single or split application of 101 kg N ha− 1 . Sprinkler irrigation consisted of three weekly applications of 0.038 m water each in 1983 and a similar scheduling to maintain soil moisture tension above –30 kPa in 1984. In 1983, sprinkler irrigation increased sheath blight ( Rhizoctonia solani ) incidence and decreased grain yield (4448 kg ha− 1 vs. 7139 kg ha− 1 under flood irrigation), dry matter production, harvest index, and florets per panicle compared to flood irrigation. In 1984, despite chemical control of sheath blight, yields averaged 5901 kg ha− 1 under sprinkler irrigation vs. 7846 kg ha− 1 under flood irrigation. Nitrogen timing did not significantly affect yields, but a weak N timing ✕ irrigation method interaction ( p =0.061) denoted that split N applications may benefit yields under sprinkler irrigation. multiple regression indicated fewer florets per panicle was the primary source of yield loss with sprinkler irrigation. Sprinkler irrigation of rice might decrease water use but it lowers yields and increases need for fungicides compared with flood irrigation.