Water management strategies and their effects on rice grain yield and nitrogen use efficiency

Abstract

Midsouthern US producers are reluctant to adopt alternate rice (<i>Oryza sativa</i> L.) irrigation techniques that could reduce groundwater withdrawal due to perceived reduction in nitrogen use efficiency (NUE) and rice grain yield. The objective of this study was to determine the impact of four rice irrigation techniques (continuous flood, straighthead irrigation, alternate wet/dry, and aerobic) on maturity, mature plant height, NUE, and rice grain yield for six cultivars commonly grown in Louisiana and Mississippi. This experiment was conducted in 2013 and 2014 at Louisiana State University (LSU) AgCenter in Crowley, Louisiana, on a Crowley silt loam (fine, smectitic, thermic Typic Albaqualfs) and at Delta Research and Extension Center in Stoneville, Mississippi, on a Sharkey clay (veryfine, smectitic, thermic Chromic Epiaquerts). Nitrogen use efficiency and rice grain yield for rice grown in an aerobic environment was reduced at least 20% compared to continuous flood, straighthead-drain management, and alternate wetting and drying (AWD) irrigation. Straighthead irrigation and AWD performed similar to the continuously flooded production system for NUE and rice grain yield. These data indicate that when properly managed use of an alternate irrigation strategy, such as AWD irrigation, does not reduce NUE, plant height, or grain yield compared to a continuously flooded system.