Optimized Irrigation

"We know the worth of water when the well runs dry." [Thomas Fuller]

Natural and political limitations on water resources are impelling growers to be ever more efficient with the water that is applied to crops. Growers are using technology to improve water-use efficiency (WUE) which is defined as a unit of water (e.g., gallon) applied per unit yield (e.g., tons). 


In summer into late fall, we’re one of the driest regions of the country. Adequate irrigation is essential for field, and container, grown plants that may get severely stressed over the long summer rainless periods. Irrigation management is especially complicated for ornamental plant growers who have different species at different ages in adjacent rows within the same field.  Irrigation decisions may also be difficult because of limited information about the cultivar-specific requirements, growers’ inexperience, and lack of unbiased information about which labor-saving technologies will be useful in agricultural settings. At Oregon State University, we address these challenges by delivering research and Extension about specific water requirements for crops grown in our unique Oregon climate.

Improvement in electronic technology and its continuous advances in developing soil moisture sensors significantly reduced the cost of using sensors in soil moisture monitoring. Nowadays many growers use soil moisture sensors for monitoring of the water status in the root zone for irrigation scheduling. Growers are provided the option of choosing among a variety of soil moisture sensors with different accuracy, limitations, and cost. At Oregon State, in collaboration with our grower partners, we are to comparing commercially available soil moisture sensors and evaluate their performance, consistency, accuracy, and affordability for the purpose of irrigation management for nursery crops.

At the North Willamette Research Extension Center, we are developing ET-based irrigation solutions. The acronym ET stands for evapotranspiration (ET), which is the process of evaporation from plant and soil surfaces and from within plant tissues (i.e., water movement through stomata). Traditional ET-based irrigation is used in conjunction with a crop coefficient to calculate the water use of a hypothetical fully-irrigated crop field. This method has been widely adopted for monoculture commodity crops such as corn, soy, cotton, alfalfa, etc. A problem with translating this method to the Nursery industry is that we have highly diversified cropping systems, and do not know have crop coefficients for most of our species. An alternative method has been developed over the past few years that estimates the specific water demand from a site, regardless of crop coefficients. This method was developed by University researchers, is based on the micro-meteorological principles of Surface Renewal, and has been commercialized as “actual ET.” I propose that establishing a demonstration site at the North Willamette Research and Extension Center to facilitate delivery of this new technology to the Oregon Nursery industry. The goal is to provide a new way of determining site-specific irrigation demands at a scale appropriate for management, field by field, block by block, and not plant by plant.