MONITORING ALFALFA WATER USE WITH SOIL MOISTURE SENSORS

Water management is key for profitable alfalfa production in the West. However it is one of the most difficult aspects of alfalfa production, in part because of the difficulty in monitoring and evaluating irrigation practices. The soil moisture content of several alfalfa fields was monitored over the last four years for the duration of the irrigation season using Watermark ® resistance blocks. Soil moisture content fluctuated considerably during the season; the driest periods corresponded with alfalfa harvests. Soil moisture content also varied greatly between growers reflecting differences in soil type and irrigation practices between farms. A potential area for improvement in irrigation management was observed at nearly all sites. The most common areas for improvement were over-irrigation in spring, under-irrigation in midsummer, and too late an irrigation starting date. Several years of research and recent commercial use have demonstrated the value of Watermark ® resistance blocks for monitoring soil moisture status, evaluating current irrigation practices, and for irrigation scheduling in alfalfa. Experience has demonstrated that routine soil moisture monitoring can significantly improve irrigation management