Report of Task Committee on Water Quality Problems Resulting from Increasing Irrigation Efficiency

Abstract

The Task Committee on Water Quality Problems Resulting from Increasing Irrigation Efficiency coordinated preparation of a series of papers that addressed the perceived effects on water quality from increasing irrigation efficiencies. This paper summarizes and integrates results presented in the requested papers, which deal primarily with salinity and nitrogen relationships, and also analyzes other ramifications of increasing irrigation efficiency. Increasing on‐farm efficiency usually connotes providing water to meet crop needs with minimal deep percolation and surface runoff. Topics examined include leaching requirements, chemical reactions on the root zone, potential hazards and benefits of reduced leaching, nitrate leaching, basin‐wide implications of increasing efficiencies, and effects on groundwater quality. Effects on erosion and the movement of pesticides are also considered. Physical changes to improve irrigation efficiency cannot be considered independently of the associated economic, social, legal, and institutional restraints. It is concluded that from a water quality viewpoint there is no reason to avoid increasing irrigation efficiency, but any such project should be analyzed thoroughly in advance to determine whether local circumstances warrant the improvements.