Plant and Irrigation Water Requirements (Rev) (Chapter V)

The primary purpose of irrigation is to provide a soil environment that will permit the germination of seeds, emergence of seedlings, the development of the root system, and supply water for plant use. Soil moisture must be maintained in a range that permits absorption of water by plant roots at a rate comparable to transpiration losses, and the soluble salt content in the root zone must not limit plant growth and water absorption. These are the important factors to be considered in evaluating "plant water requirements." Other factors may be involved, such as: The maintenance of a suitable soil moisture content that will not limit soil aeration, maintenance of a favorable soil temperature range for better quality crops, prevention of injury to young seedlings planted in arid climates. The planner and operator of sprinkler irrigation systems must know both the seasonal and peak irrigation water requirements for the crops that will be raised on a field, farm, or project in order to design and prescribe operational procedures for a sprinkler system that will provide moisture to the soil and plant for optimum production of quality crops. Seasonal evapotranspiration water requirements are the basis for determining the total water requirements and the irrigation water requirements of a crop, field, farm or project. For efficient irrigation, the variation in water use by a crop from emergence to harvest should be known by the operator