The Effect of Various Water Management Strategies on Rice Yield, NUE, and Soil Chemical Properties on a Sharkey Clay Soil.

The Mississippi Alluvial Aquifer is heavily relied on for irrigating intensively managed crops in the “Delta”.  The 30 year decline of this important resource is cause for concern regarding its sustainability.   Therefore, irrigation of crops including rice should be done in the most efficient manner.  The objective of this study was to evaluate rice irrigation strategies with the goal of maintaining or improving grain yield.

An experiment was conducted in Stoneville, MS, on Sharkey clay (Chromic Epiaquerts) soil.   Six popular southern USA cultivars (‘Cheniere’, ‘CL151’, ‘CLXL729’, ‘CLXL745’, ‘Jupiter’, and ‘Presidio’) were drill-seeded in a randomized complete block design within each of four irrigation schemes.  The irrigation schemes were:  1) Continuous flooding; 2) Flush irrigation (aerobic); 3) Intermittent irrigation; and 4) Straighthead drain irrigation.  Plots were managed for drill-seeded, delayed-flood rice culture.  At maturity, plots were harvested with a small plot combine. Total above ground biomass was collected from 0.9 m of row at panicle emergence, oven dried, ground and analyzed for total N content. Watermark soil moisture sensors were used to trigger irrigation when soil moisture reached 20-30 centibar range for the flush and intermittent irrigation schemes.  In the intermittent scheme, a full flood was established and allowed to soak between cycles.  For the flush irrigation, the flood was maintained for 12 hours then released.

Grain yield and total N uptake were not affected by the interaction of cultivar and irrigation scheme. Grain yield and total N uptake were the greatest and not different from each other with continuous flooding, intermittent irrigation and straighthead drain irrigation.

These data suggest there are two alternative water management schemes that can maintain grain yields.  Nitrogen management would need to be altered to achieve greater yields in the flush irrigation treatment.  Finally, the need for a continuous flood was not warranted in this study.