Furrow Irrigation for Mid-South Rice Production.

Rice irrigation currently accounts for the greatest amount of irrigation water applied per acre over corn, soybeans, and cotton in the mid-south. The alluvial aquifer serves as the major source of irrigation water for rice production in Mississippi; however, it is declining at a rate of 37,000 ha-m yr^-1 and has done so for approximately 35 years. An experiment was conducted at the Delta Research and Extension Center in Stoneville, MS to evaluate the yield and physiological response of rice to alternate wetting and drying (AWD) and furrow irrigation practices as compared to a continuous flood. Three rice cultivars were evaluated in six different rice irrigation treatments that include: a continuous flood, optimized AWD, and furrow irrigation with water level thresholds at 10 cm below the soil surface, 20 cm below the soil surface, 30 cm below the soil surface, and 40 cm below the soil surface. Water level in each paddy was monitored and irrigation events were triggered at each respective threshold back to a 10 cm flood for continuous and AWD, and 40 ha-mm was applied for furrow irrigation. Additionally, five fertilization treatments totaling 168 kg N ha^-1 were applied at different split intervals (100, 75/25, 50/50, 50/25/25, 25/25/25/25) according to growth stage. Conventional and Clearfield herbicides were applied at different growth stages and evaluated for weed control. Data from this experiment suggest that furrow irrigation for mid-south rice production may be economically feasible, and results of furrow irrigation water management strategies on total water use, rice yield, weed control and economic return will be discussed at length. Water management practices that reduce groundwater withdrawals are a viable option for rice producers in the mid-south.