IJRAFS Volume 5

DEVELOPMENT OF EFFICIENT WATER MANAGEMENT STRATEGIES FOR RICE IN THE YALA SEASON ON NON CALCIC BROWN SOILS OF THE AMPARA DISTRICT OF SRI LANKA- A FIELD STUDY

The principal objective of this study was to evaluate alternative water-saving irrigation regimes for rice cultivation in the yala season on Non-Calcic Brown soils in the Ampara district with a view of reducing total water input while ensuring minimum or zero yield reductions. The field experiments were conducted at Ampara during the yala seasons of 2006 and 2007. Seven water-saving irrigation treatments were imposed as following: Standing water (SW) throughout (T1); SW during vegetative (VEG) and reproductive (REP) stages and saturated soil conditions (SAT) during grain-filling, GF, (T2); SW during VEG followed by SAT during the rest (T3); SW during VEG followed by SAT during REP and allowing to dry down to crack formation (CF) during GF (T4); SAT throughout (T5); SAT during VEG and REP followed by CF during GF (T6) and SAT during VEG and CF during the rest (T7). The two yala seasons differed in their weather patterns, with 2006 being a typically dry yala season with very little mid-seasonal rainfall while 2007 being a relatively wet yala season with mid-seasonal rainfall during all three phenological stages of the crop. In 2006, vegetative growth of the rice crops, measured in terms of leaf area index (LAI) and total dry weight (TDW) decreased with decreasing water availability across the seven experimental treatments. . …