The economics of sprinkler irrigation uniformity for lettuce production with in-season rainfall

Abstract

Irrigation non-uniformity has been shown to adversely affect crop production and it is often assumed that high levels of uniformity are required to optimise economic returns. However, sprinkler irrigation systems used for lettuce production in the Lockyer Valley, Australia commonly operate with low uniformity. Despite lettuce being a relatively high value crop there appears to be little evidence that growers in this region identify low application uniformities as a constraint to either crop production or economic returns. Local relationships between marketable lettuce yield and water application for two seasons were obtained from previous field trials. These relationships were used to model the field scale crop yields and returns for irrigation systems operating with various application uniformities and under different in-season rainfalls. Implications for identifying optimum levels of irrigation system performance with in-season rainfall are discussed.