University of Florida


Update of Net Irrigation Requirements for Turfgrass

Sponsor: Southwest Florida Water Management District

Timeline: 1/14/2010 – 8/31/2011


Calculation of net irrigation requirements for turfgrass is essential for determining water allocation and irrigation scheduling.  In the past, net turfgrass irrigation requirements were published in Bulletin 200 “Water Requirements of Florida Turfgrasses”.  This document is no longer available via EDIS and needs to be updated with current ET estimation techniques and simulation of turfgrass water requirements. 

Bulletin 200 used monthly values of ET determined by the McCloud method along with methods from TR-21 to determine effective rainfall.  In the early 1980’s when this publication was developed these methods were state of the art.  However, new methods to estimate ET have become available, including the ASCE-EWRI Standardized Evapotranspiration Equation.  In addition, it is generally considered that a daily soil water balance is most accurate at determining plant water requirements.

The Southwest Florida Water Management District is funding a five year study to "Investigation and Development Methods to Determine Urban Landscape Irrigation for Planning and Permitting in Central Florida (P424).  It is expected that P424 will identify appropriate landscape coefficients for permitting water use.  Crop coefficient data are an essential input to the net irrigation requirement. It is anticipated that existing data on crop coefficients as well as data determined in P424 will be used in this proposed work.


  1. Gather and quality check climate data from cities around Florida to represent climate conditions from the panhandle down to south Florida.
  2. Calculate reference ET (ETo) via currently accepted scientific methods for each site with weather data.
  3. Perform a daily irrigation water requirements simulation with daily precipitation data, daily calculated ETo, and literature data for other input values.
  4. Create an internet web page with a summary of turfgrass and landscape water requirements information with links to detailed information.