Optimum irrigation management generally involves partial irrigation of some crops to maximize net returns, particularly when water supplies are limited. This management paradigm is substantially more challenging than full irrigation to maximize crop yields, and few irrigators have the resources or capacity to deal with it quantitatively. Oregon State University and NRCS have created a web-based irrigation advisory system for optimum irrigation management. The system is being developed in two

more »

... ses. The first phase, now largely completed, supports conventional irrigation scheduling. Key features of the first phase are: (i) application efficiencies are explicitly analyzed for each irrigation strategy considered; (ii) When water supplies or delivery system capacity are limited, the system provides simultaneous scheduling of irrigations in all fields that share a water source; (iii) the user interface permits farm managers to participate directly in searching for an optimal strategy using a robust, interactive web interface to stipulate objectives and constraints of irrigation strategies. A pilot advisory service was initiated in Central Oregon in 2006 and will be made available on the USDA national web farm for use by NRCS cooperators in 2008. The second phase is incorporating new analytical tools that will enable the advisory service to ore effectively support optimal irrigation management, including management of partial irrigation when water supplies are limited. Key elements of the second phase are (i) a statistical model of crop development and potential yield to estimate yields under partial irrigation; (ii) a feedback system to reconcile conflicting estimators of soil moisture depletion. Incorporation of the second phase will begin in 2008, but it is expected that refinement of these tools will continue indefinitely.