What is Flood Irrigation?
Flood irrigation starts with the opening of a valve at the head of the field and the water moves across the surface of the entire field until it reaches the end. Flooding the field is the most common irrigation method for alfalfa but the least water efficient and least uniform application. This makes for an extremely uneven harvest. Additionally, it takes a long time to move the water through all the sections of the field.
Flood irrigation saturates the soil causing temporary anaerobic conditions. This is the single greatest cause of alfalfa crown weakness and mortality. The second greatest cause is the stress between flood irrigations that is required to accommodate harvesting equipment.
Additionally, flood irrigation causes the surface of the ground to stay wet for a prolonged period after irrigation, and this creates an environment which is favorable to deleterious insects and disease. The result is a progressively weaker stand that lasts only four years on average.