PERSPECTIVES ON DEFICIT IRRIGATION

An analysis of deficit irrigation in three quite different situations was conducted to better understand the potential benefits and risks as sociated with this irrigation strategy. Existing crop yield functions and cost functions, developed independently of the present research, w ere used to estimate the levels of applied water that would produce ma ximum net income in each situation. These same functions were also use d to estimate the degree to which the three crops could be under-irrig ated without reducing income below that which would be earned under fu ll irrigation. The analysis encompassed wheat production in the northw estern USA, cotton production in California and maize production in Zi mbabwe. Results suggest that (1) deficits of between 15% and 59% would be economically optimal, depending on the circumstances, and (2) the estimated margin for error in these estimates is quite wide.