Effects of urea types combination with alternate wetting and drying irrigation on rice yield in the Vietnam Mekong Delta

Abstract

A field experiment was arranged with a split-plot design with three replications, two irrigation methods including continuous flooding (CF) and Alternate Wet Drying (AWD) combination with three amounts of two fertilizers, nitrogen White Urea and Black Urea. Actual yield, yield components, leaf N content, and chlorophyll index were investigated. The results showed that AWD application saved 9.5% of freshwater. Compared with FC, OM18 did not respond to AWD combination with white and black urea. Applying 100 or 120N of both nitrogen types gave better performances in panicles, filled grain, and yield under both FC and AWD. Regarding OM 18 yield, 100N (Black Urea)– 80 P2O5 – 60K2O in CF gave the best yield (8.0 tons/ha), but this treatment showed non-significant differences from 120N(Black Urea) – 80 P2O5– 60K2O in AWD as well as 120N (Black Urea) – 80 P2O5 – 60K2O in CF (7.2 tons/ha). OM 18 responded to Black Urea better than White Urea under AWD and FC. OM 18 showed the best yield in 100N(Black Urea) – 80 P2O5 – 60K2O under CF. AWD application saved up to 9.5% freshwater.