CONJUNCTIVE USE OF WATER AND ITS MANAGEMENT FOR ENHANCED PRODUCTIVITY OF MAJOR CROPS ACROSS TERTIARY CANAL IRRIGATION SYSTEM OF INDUS BASIN IN PAKISTAN.

Farmers in Pakistan either rely only on groundwater or manage conjunctive use of surface and groundwater for irrigating crops due to shortage of canal water. Present study was undertaken to find variations in conjunctive water management practices, groundwater productivity and crop profitability in Chuharkana irrigation sub-division in Punjab. Physical and questionnaire based data were collected from 120 farmers using stratified random sampling technique from vicinity of four watercourses of Lagar distributary. Trajectory method was employed to measure tubewells' discharge for evaluating groundwater productivity across watercourse reaches. EC, SAR and RSC were measured to evaluate groundwater quality. Results show prevalence of surface and groundwater use for irrigation. Area under conjunctive use decreased from 76.6% at head to 46% at tail due to decreased canal water supply towards tail while area irrigated by groundwater-only increased from 20% to 54% across head to tail. Analysis of groundwater samples showed lower quality levels. EC, SAR and RSC ranged between 1.27-1.55 dS m-1, 6.39-9.54 (mmol L-1)1/2 and 3.75-4.18 meL-1 respectively, with higher values towards tail. Groundwater productivity for wheat was relatively higher at the head, while that of rice did not vary much across watercourse reaches. Conducive soil conditions and more reliance on groundwater for timely irrigation resulted gross margins at the tail. [ABSTRACT FROM AUTHOR]