MANASOTA & PEACE RIVER BBDs Meeting Notebook 10-21-09.docx

B266
Accounting For Interception of Sprinkler Irrigation Water by
Container Grown Plants
Project Type Basin Initiatives
AOR(s)
Water Supply, Flood Protection, Water Quality
Basin(s) Alafia River, Hillsborough River, Withlacoochee River, Peace River, Manasota
Cooperator(s)
University of Florida
Project Manager COHEN, RON
Task Manager(s)
Status Ongoing
Description
The plant canopy plays a critical role in the interception of sprinkler irrigation water. Depending on the size and
architecture of the canopy, as well as the container spacing, interception of irrigation water can be greater than or less
than the amount of irrigation water that would fall into the container. Typically, interception is considered a water loss
and not accounted for when supplying irrigation water. This project will quantify the amount of water that is intercepted
by the plant and funneled to the plant's container. By accounting for this intercepted water, the overall amount for
irrigation management can be reduced. The industry is supportive of this project and will provide funds to reduce the
overall project results.
Benefits
Information from this project will help container nursery producers improve their irrigation efficiency and conserve
water. The amount of water saved will be a function of the number of acres planted and their water use, which will
change annually based on market and climatic conditions. Using the District's regulatory database and assuming an
annual 5% water savings from only nursery production, there would be an annual savings of about 1.9 mgd.
Costs
This three year project will cost the District a total of $91,125. Funding for this project is prorated between five Basin
Boards (Peace River - 23%, Hillsborough River 22%, Alafia - 18%, Manasota 18% and Withlacoochee 11%) based on
the number of permits for nursery production in their watershed. In FY2009, FY2010, and FY2011 the Basin Boards
will budget each year: Peace River $7,471, Hillsborough River $7,255, Alafia River $5,945, Manasota $5,944 and
Withlacoochee River $3,760.
Additional Information
Determining the interception factor (IF) for commonly grown plants with a wide range of plant growth habits (e.g.
globose, upright spreading, broad spreading, etc.) and at different spacings between containers, will help growers
improve their efficiency and reduce water use. For example, sweet viburnum, which has been found to have an IF of
>2 during the last month of production, would only require ¼ inch of irrigation water to supply ½ inch to the container at
that latter stage of production. In two experiments where water scheduling was based upon container weight loss, the
irrigation rate averaged 0.2 inch/day using IF, but would have averaged 0.3 inch/day ignoring IF. This represented a
total water savings of 14 inch (0.1 inch/day over a 140 day crop). As more and more nurseries base irrigation
scheduling on evaporative demand (water loss per container) knowing the interception factor at various stages of
production would be critical in determining the actual irrigation requirements of a crop. For mixed plantings, this
information will add further precision to grouping plants not only by evaporative demand (current BMP), but also by
their irrigation interception characteristics. Currently, this information is limited to a few species (Beeson and Yeager,
2003). Data are needed for a wide range of plant growth habits at different stages (sizes) of plant growth with various
container spacings in order for this information to be useful for growers and water managers.
021 - Manasota Basin 168