The study was repeated in 1984 but with disease control and split nitrogen applications. Yields were reduced 25 percent mainly due to fewer tillers per area, fewer florets per panicle, and a slightly lower specific grain weight. Under this management system there was a 25 percent yield differential between sprinkler and flood irrigated rice. However, only specific soil types can be effectively irrigated using sprinkler systems. Preliminary tests indicated that rice production under sprinkler irrigation on adapted soils can be economical in four of five years using 24 acre-inches of total water.
Total water includes both effective rainfall and irrigation water.
Effect of water stress levels during specific rice growth stages have received little research effort. Rice production in the U.S. depends on a highly mechanized, intensively managed system. All rice in the U.S. is direct seeded and grown under controlled irrigation. Therefore, little international research on water management is applicable to U.S. rice. Texas has a statewide water deficiency largely because ground water extraction exceeds recharge.