Drainage-Subirrigation Design For Pelham Loamy Sand

Abstract

ABSTRACT This project was conducted on the Bell farm located in Pierce County, GA on Pelham loamy sand soil. The study area included 40 ha of land under controlled drainage-subirrigation (CD-SI) system of which 38 ha were in blueberries. The system installation included two drain spacings of 15.3 and 20 m, and two types of control structures for the drainage system outlet water level, which were an open ditch and a closed conduit system network. The blueberry section of the field was in a closed conduit system network with lateral drains spaced at 15.3 m. Seventeen punch-tape recorders were used to measure the water table elevations in the soil profile within the field over the drain tiles, and midway between drainlines, at the open ditch and closed system control structures (one for each), and in an undrained-nonirrigated section of the farm. A punch-tape rainfall recorder was also used to measure rainfall at the site. Surface runoff, drainage effluent, or subirrigation volume was not measured. Experimental results showed that the water table and soil-water conditions could be adequately managed in the blueberry field, thus excellent crop growth and yield resulted. DRAJNMOD, a water management model for shallow water table conditions, was used to simulate the system performance for the study site. Simulation results indicated that a subsurface drain spacing of 20 m is satisfactory for controlled drainage-subirrigation (CD-SI) systems for Pelham loamy sand soils in Pierce County, GA. Simulations were done using 20 years of climatological data from Augusta, GA. Additional research is needed to develop specific design guides for other soil types in the Georgia Flatwoods region.