14-05-2012, 05:30 PM
SENSOR-BASED AUTOMATION OF IRRIGATION OF BERMUDAGRASS
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INTRODUCTION
Turfgrass is the main cultivated crop in Florida with nearly four times the acreage
as the next largest crop, citrus (Hodges et al., 1994; United States Department of
Agriculture [USDA], 2005). Irrigation of residential, industrial, commercial, and
recreational turf areas is necessary to ensure acceptable turf quality. As a consequence of
problems related to drought, coupled with a steadily increasing demand for water
resources, the state of Florida has imposed restrictions on irrigation water use. Water
used for turfgrass irrigation, however, remains to be publicly discussed. The development
of Best Management Practices (BMPs) for irrigation water use in landscapes has become
an undeniable strategic, economic, and environmental issue for the state. New irrigation
technologies could improve irrigation efficiency, promoting water conservation and
reducing the environmental impacts of turfgrass culture, which is a major component of
landscapes in Florida.
Water
Florida receives an average of around 1400 mm of rainfall a year (National Oceanic
and Atmospheric Administration [NOAA], 2003). Unlike many areas dependent on
irrigation, annual rainfall in Florida typically exceeds evapotranspiration. Nevertheless,
irrigation is required because total annual rainfall for Florida typically varies both
geographically and temporally (USDA, 1981; Carriker, 2000). Such rainfall variation has
a direct impact on surface water and groundwater supplies. Lack of rainfall for even a
few days causes depletion of moisture in sandy soils commonly found in Florida; along
with reduction of stream flow and groundwater recharge (Carriker, 2000; National
Research Council, 1996).
Water Demand
Florida has the second largest withdrawal of groundwater for public supply in the
United States (Solley et al., 1998). Groundwater was the source of more than 88% of the
water withdrawn for public supply in 1990 (Carriker, 2000). In 1995, nearly 93% of
population in Florida used groundwater as a drinking water source (Solley et al., 1998).
Water withdrawals for public supply in Florida have increased rapidly, from 600,000
m3/day in 1950 to 7.3 million m3/day in 1990 (Carriker, 2000). The population served by
public-supply systems increased from 5.42 million in 1970 to 11.23 million in 1990
(Marella, 1992).