Study on feasibility of drip irrigation in shallow ground water zones of eastern India
Although the effectiveness and economics of drip irrigation systems are well established in areas having undulating topography and water scarcity, its economics in plain areas bestowed with good quality ground water at shallow depths are not yet studied. Due to this, there is confusion among farmers as well as planners regarding the guidelines for selection and propagation of this system in such areas. This study attempts to evolve guidelines for deciding the economic threshold value of fixed cost of drip irrigation system for sugarcane crop. Nomographs have been developed to find the threshold value of economic fixed cost of drip irrigation system (exclusive of pumping unit) for a combination of variables, depth of water table, yield level under check basin irrigation, expected yield gain with adoption of drip system, irrigation requirement with check basin, and electricity charges. The perusal of nomographs shows that the factors influencing the economics of drip irrigation in order of importance are yield gain ratio, electricity charges, irrigation requirement and depth of ground water.
Investment decision model for drip irrigation system
Drip irrigation is becoming popular in India although the decision to shift to drip irrigation from surface irrigation is not backed up by solid economic factors. It is not that the factors do not justify the shift, but that insufficient study has been done to document the conditions under which a change is justified. The investment decision for shifting to drip irrigation will depend upon many factors; including cost of cultivation, productivity, yield gain factor, cost of produce, electricity charges, depth of groundwater and irrigation requirement. These parameters vary from crop to crop, place to place, size of plot, and farmer to farmer. Therefore a sweeping recommendation suitable for all conditions cannot be made. In view of this, a software program has been developed for estimating the threshold economic value of the investment cost of drip irrigation. In addition to the threshold value of investment cost, the software provides information on energy consumption and net return. The software can be used both for annual crops such as sugarcane or seasonal crops such as vegetable rotations (winter–summer). To demonstrate the interdependence of various input parameters, an analysis has been made using local data in this software. The analysis has provided the relationship between the investment cost and the yield gain factor, the returns from the crop, as well as the savings in energy and the size of the prime mover with regard to the size of the farm.
Irrigation planning: 1. Cropping pattern
Irrigation programs, specified in terms of dates and depths of irrigation, are developed for corn, grain sorghum and pinto beans. The information contained in the irrigation programs for each crop is applied in an area-allocation model to determine a cropping pattern for the three crops. The area-allocation model is a linear optimization model which maximizes gross margin from yields of crops under consideration subject to total water supply, maximum amount of water that can be delivered for irrigation purposes on any date of irrigation, and irrigation labor. The land area to be allocated to each crop for planting is the decision variable. Results from the area-allocation model include cropping pattern, gross margin, total irrigation depth on each date of irrigation, total irrigation labor, and crop yield. Sensitivity analysis is performed to study the effect of changes in crop prices on the optimal results.