Demonstration of the Benefits of Subirrigation Using Water Level Control Structures for Improved Agricultural Irrigation Water Use

Changes in climate and subsequent weather patterns are challenging water availability and timing to
agricultural crops in Western Washingtons Mediterranean climate. Characterized by wet winters and
dry summers, the use of irrigation water in the summer months is critical to crop productivity. In
Whatcom County, WA, berry, potato, and dairy crops (silage corn and grass), account for 80% of all
agricultural acres and support the 2nd (milk) and 4th (potato) largest commodities in the state, and the
commodities for which Washington ranks 1st (berry) and 2nd (potato) in the nation. Whatcom County
berry sales were over $110 million in 2017, surpassed only by the dairy industry with over $180 million
in milk sales in Whatcom County. To meet these vital production and quality measures,
these crops need irrigation in the dry summer months to optimize crop growth. The overall goal of this project is to enhance the economic and environmental benefits of agricultural irrigation water. This project will examine the impact of implementation of the NRCS Structure for Water Control (587) Practice Standard for subirrigation to reduce surface irrigation requirements in corn and grass silage rotations while maintaining or improving crop production and reducing negative impacts on water quality. Real‐time soil moisture sensors will be used to inform the need for surface irrigation and to identify easy metrics for producers to monitor and adjust irrigation water use. Soil, groundwater, and surface water sampling will be utilized to assess impacts on soil and nutrient dynamics. The project’s overall objectives are: 1) to determine the effectiveness of subirrigation with WLCS for increasing
water use efficiency1 and reducing nutrient leaching, and 2) to improve farmer decision support related
to surface irrigation with demonstration of automated real‐time moisture sensors.