Site-Specific Management of Agricultural Inputs: An Illustration for Variable-Rate Irrigation.

The efficiency of agricultural inputs may be reduced by ignoring the inherent variability in soil texture and the non-uniformity of the input's application. This paper focuses on variable-rate irrigation, which is performed via subdivision of the spatially variable field area into a controlled number of individually irrigated management units (MUs). The impact on profits and input decision of the MUs' size, the (technology-dependent) degree of irrigation uniformity, and the (cultivation-dependent) soil properties is investigated. A framework to evaluate the loss from imperfect information about the spatially random soil properties is developed and applied to sweet corn production. The analysis suggests that utilisation of site-specific farming and adoption of improved irrigation and/or cultivation technologies do not guarantee water saving. Copyright 2000 by Oxford University Press.