Abstract:
Furrow irrigation necessitates the wetting of only a part of the surface of land, thus reducing evaporation losses, lessening the puddling of heavy soils and making it possible to cultivate the soil sooner after irrigation. Surge irrigation in furrows possesses the capability to increase irrigation efficiency, by ensuring water saving, better uniformity and reduced tail water losses in different soil and site conditions. To assess the suitability of the system for use in the sandy loam soils of Tavanur region, and to obtain suitable management parameters for surging in the area, a study was conducted at the Instructional Farm of KCAET, Tavanur. Continues flow was compared with surge flow of cycle ratios ½, 1/3 and 2/3 with cycle times 6.9 and 7.5 minutes for discharges of 1.3, 1.7, and 2.1 lps. Data of advance time, depth of flow and inflow-outflow measurements were collected during field irrigation runs.
Surge flow in all cases advanced faster compared to continuous flow. For cycle ratio ½ the reduction in advance time ranged as 14.59, 22.8 and 14.77 per cent for the three discharge rates. In the case of cycle ratio 1/3, the reduction was 37.6, 41.94 and 38.01 per cent respectively, whereas for cycle ratio 2/3, the reduction was 34.29, 32.83 and 22.73 per cent respectively. Infiltration variability was lesser under surge flow and the values of infiltrated volume and infiltrated depth at various sections along the furrow length was lesser. Surging with cycle ratio 1/3 and a discharge of 1.3 lps showed the least variability in infiltrated depth and the greatest uniformity of application. Infiltration rate was found to decrease significantly along the length of the furrow and between consecutive surges. The lowest intake rate was obtained for surge flow of cycle ratio 1/3. Surging with cycle ratio 1/3, and a discharge of 1.3 lps required only 1.11 m3 of water to complete the advance. This was the least value compared to continuous flow and other surge flow cases. Analysis of variance of the volume required to complete the advance indicated significant difference between flow types at 5 per cent and 1 per cent levels. The variation between discharges was also significant at 5 per cent and 1 per cent levels. Thus surge flow proved advantageous compared to continuous flow in the sandy loam soils of Tavanur region and surging with cycle ratio 1/3 and a discharge of 1.3 lps was chosen as the best out of the selected treatments for the study.
