Water & Agriculture
Globally, 70% of fresh water is used for agricultural purposes (FAO, 2016). In the United States, agricultural systems use 80% of the nation's fresh water to keep up with today's food demand (USDA, 2019). In Hawaiʻi, farmers irrigate up to 6 times a day. Thus, efficient irrigation practices are necessary for the future of Hawaiʻi's food security.
(FAO, 2016)
Current Irrigation Practices
The two causes of inefficient irrigation are: 1) under-irrigation, which results in reduced crop yield, and 2) over-irrigation, which results in unsustainable water use and environmental issues. Current irrigation practices are experiential and based on trial and error, most likely resulting in over-irrigation. Investing in irrigation management tools that recommend accurate irrigation schedules will help promote sustainable agriculture while conserving precious water resources.
Irrigation Scheduling Tool
(CropManage, n.d.)
A web-based management tool started in Salinas Valley, CA called CropManage was developed. CropManage recommends irrigation and nitrogen schedules based on algorithms that incorporate real-time rainfall and evapotranspiration data, crop characteristics, and soil water retention data (Cahn & Johnson, 2017). Adapting tools such as CropManage is necessary to ensure the sustainability of HawaiÊ»i’s food systems.
Check it out here
Soil Water Retention
(Brady and Weil, 2010)
Soil water retention vary across Hawaiʻi's diverse agricultural soils. Field capacity (ranging from -10 to -33 kPa) is an important moisture state because the soil is at optimal water content. At optimal water content, the right amount of air, water, and soil exists to promote root growth (Brady and Weil, 2010). Soil water characteristic curves are empirically determined and allow us to visualize soil water retention behavior. A model that can predict soil water characteristic curves is a critical component in irrigation management tools such as CropManage.
Research Goal
The goal is to improve our understanding of the key properties that control soil water retention across the Hawaiʻi's diverse range of agricultural soils. An improved understanding of soil water retention behavior will help adapt the CropManage approach to irrigation scheduling in Hawaiʻi.
References
Brady, N. C., & Weil, R. R. (2010). Elements of the Nature and Properties of Soils (Third). Upper Saddle River, NJ: Prentice Hall.
Cahn, M., & Johnson, L. (2017). New Approaches to Irrigation Scheduling of Vegetables. Horticulturae, 3(4), 28. https://doi.org/10.3390/horticulturae3020028.
CropManage. University of California. Retrieved from https://cropmanage.ucanr.edu/Home/SplashPage?ReturnUrl=%2F.
FAO. (2016). AQUASTAT website. Food and Agriculture Organization of the United Nations (FAO). Retrieved from http://www.fao.org/nr/water/aquastat/water_use/index.stm.
United States Department of Agriculture. (2019). Irrigation and Water Use. Retrieved from https://www.ers.usda.gov/topics/farm-practices-management/irrigation-water-use/.