The economics of irrigation with nonuniform infiltration

Economic implications of nonuniform water infiltration in irrigated fields can be assessed with a simplified hydrologic balance model linked to an economic optimization model through a crop water production function. The effects of nonuniformity are derived by using two production functions that differ in terms of the sensitivity of yield to applications of water greater than that needed to achieve maximum yield. Where crop yield is sensitive to excess water, productivity and optimal levels of water application are lower in nonuniform fields than in uniform fields. If crop yield is not sensitive to excess water, outcomes depend on the price of water relative to crop income net of water costs. The conclusions, then, depend crucially on the form of the production function. An example is used to demonstrate that irrigation technology and management that increases the uniformity of infiltration may increase both productivity and the levels of agricultural water use.