EVALUATION OF IRRIGATION APPLICATION METHODS FOR RICE PRODUCTION

This clay soil study was carried out in Dodai and Dhandi minors command area of Larkana and Tando Muhammad Khan districts in Sindh, during 2005-2007. The study consisted of the following treatments: (a) Traditional irrigation method also called pancho in local language, (b) Irrigation as required i.e. application of water after an interval of ten days, (c) Irrigation at an interval of seven days with the main focus to compare pancho irrigation with scheduled irrigation systems for growing rice crop. These treatments were replicated thrice in a Randomized Complete Block design. During the study impact of different treatments on electrical conductivity, sodium adsorption ratio, soil infiltration rate, water table depth, groundwater quality and crop yield was monitored. Soil samples from 0-15, 15-30, 30-60 and 60-90 cm depth were collected for determining the physico-chemical properties. Soil infiltration rate was measured with the standard ring method. One observation well was installed at the experimental site to monitor water table depth and groundwater quality. Crop yield estimation was carried out on whole plot basis. Soil analysis shows that with the passage of time salinity build up occurred at watercourse 4R, Dodai minor and 16L, Dhandi minor whereas at watercourse 17- CR it showed a slight decrease. The increase might be due to a rise of saline groundwater at watercourses 4R and 16L. The SAR showed depth-wise increase as compared to initial values. Soil infiltration rate decreased over the time period at watercourse 17-CR whereas it has increased at watercourse 16L. The water table data shows that the variation trend over the time period was prominent and it ranged between 0.63 to 0.84 meters and 0.51 to 1.74 meters at watercourse 17-CR and 16L, respectively. The EC of groundwater ranged between 1700 to 1800 ppm and 1400 to 3400 ppm, which is considered from good to hazardous at watercourse 17-CR and 16L respectively, whereas the SAR remained within safe limits and ranged between 1.3 to 1.6 and 3.3 to 14.4 at watercourse 17-CR and 16L , respectively. The crop yield data revealed that the higher rice yield was obtained in T1 followed by T3 at all the watercourses.