Comparison of Evapotranspiration from Citrus Groves in Flatwoods and Ridge Soils

Abstract

Citrus is one of the most important agricultural crops in Florida. Citrus groves are typicallylocated in two soil profiles: flatwoods and ridge. Flatwoods soils are poorly drained fine texturedsands with organic matter in the shallow root zone, which require less frequent field irrigation with alonger duration when using a fixed flow rate. Ridge soils are fine to coarse textured sands that havevery little water holding capacity; therefore, irrigation water is supplied more frequently with a shorterduration. Water flow in the soil profile differs primarily because of water table depth, but also becauseof variability in soil properties. Citrus evapotranspiration (ET) is affected by tree size, tree spacing,ground cover, and climate as well as the difference in root structure and root water extraction causedby different soil conditions. Accurate estimation of ET from citrus groves is limited by a lack of astandard method and is time consuming because most methods use a soil water mass balance atthe soil surface. The eddy correlation method is a reliable technique that measures the turbulentfluxes of water vapor and sensible heat. In this study, eddy correlation systems were placed abovethe citrus canopy in two locations, one in flatwoods soil and one in ridge soil. The results provideddaily and seasonal patterns of ET for the two soil profiles, improving the accuracy of ET for futurewater-resource management strategies.