Assessing Pre-canal Irrigation Scenario of Soil, Water and Crop in Head-reach of Indira Sagar Command

Abstract

Off late, it has been conjectured that due to improper management of irrigation, every year as much area goes out of cultivation as is brought under irrigation in India. Introduction of canal irrigation is a latest development in Indira Sagar command. As such, the study was conducted to generate database to assess pre-canal irrigation scenario on soil, water and crop in Vertisols and associated soils of head-reach of Indira Sagar command so that afterwards it can be compared with post-canal irrigation scenario to plan strategies for enhancing production on sustainable basis in the region. The study reveals that among the fitted equation to rainfall and concurrent runoff data the highest coefficient of determination was found in case of polynomial relationship as 0.998 which is highly significant and can be successfully used in predicting runoff values in Indira Sagar Command. The order of suitability of fitted equations is observed as polynomial, power, linear, exponential, and logarithmic based on coefficient of determination values of 0.99, 0.99, 0.98 0.96 and 0.93, respectively. The value of runoff coefficient (a) was ascertained 32% which can be suitably used for estimating value of precipitation runoff (Qpro) in black soils of Indira Sagar Command in the Conceptual Irrigation Return Flow Model (CIRF Model). The water table fluctuations in 13 wells during 2005 and 2012 ranged from 2.50 to 5.1 m and 0.70 to 4.9 m, respectively during pre-canal irrigation period which in turn indicates safe water table depth for crop production but showing rising trend. Estimated values of water-quality parameters clearly indicate that waters are of good quality for irrigation. Estimated values of pH, EC, SAR and RSC are found in the range of 7.21 to 7.40, 0.36 to 0.39 dS m-1, 0.82 to 0.95 and 0, respectively. Soybean appears to be major kharif crops having largest grown area in between 103232 to 165380 ha with average productivity 1150 kg ha-1 followed by cotton with grown area in 1 between 63392 to 76191 ha and average productivity 967 kg ha-1. Similarly, in Rabi Wheat appears to be major crop with largest cropped area in between 49446 to 82399 ha with average productivity 1927 kg ha-1. The values of SYI for various crops obtained indicate that yield of all the kharif crops were sustainable over the period 2001-10. The values of SYI obtained were 0.67 and 0.53 for major kharif crops soybean and cotton respectively. It implies less sustainable yield over the period. Similarly, the SYI values of major rabi crops wheat and gram were 0.81 and 0.66, respectively indicates reasonable yield sustainability. The estimated values of N, P, K, OC, EC pH and ESP around Kelwa distributary are ranging in between 119 to 208 kg ha-1, 5.6 to 13.6 kg ha-1, 320 to 560 kg ha-1, 0.23 to 0.52 %, 0.27 to 0.71 dS m-1, 6.74 to 7.51 and 1.02 to 4.26 and around main canal are ranging in between 90 to 280 kg ha-1, 5.6 to 16.0 kg ha-1, 320 to 620 kg ha-1, 0.25 to 0.76 %, 0.36 to 0.87 dS m-1, 6.80 to 7.68 and 1.17 to 8.21, respectively. As an ultimate fall out it can be inferred to that pre canal irrigation scenario in head reach of Indira Sagar Command is absolutely normal in terms of physico-chemical properties of soil, depth of water table for growing crops, quality of irrigation water, however, there is enough scope to improve productivity sustainably