Irrigating Crops with Subsurface Drip On Coastal Plain Soils at the Wiregrass Research Station

Cotton grown in Southeast Alabama is mostly dryland due to the depth of the aquifer.  Many fields in Southeast Alabama are small and do not lend to a center pivot irrigation.  With precision agriculture and auto steer tractors, growers are able to adopt the technology of subsurface drip.  Originally installed in 1999, a subsurface drip system has recently been re-evaluated by incorporating precision tillage in a peanut and cotton rotation.  The test consisted of eight blocks with twenty 36 inch rows by 210 feet.  Inside each block was 5 sub plots consisting of 4 rows.  Of these 5 sub plots, two were subsurface drip irrigated at a flow rate of 0.25 gal/hr/emitter and two sub plots drip irrigated at 0.37 gal/hr/emitter.  The fifth sub plot in each block was non-irrigated.  The two different flow rates of drip tape were for evaluation of the length of time it takes the same amount of water to be applied to the crops.  The drip tape has been buried at a consistent depth of 15 inches directly between the two yield rows.  There were six blocks devoted to cotton and two devoted to peanuts.  All plots were strip tilled.  The irrigation amount was determined by a chart based on crop canopy and pan evaporation, monitored daily during the growing season.  Sub plots within each block of cotton and peanuts were harvested independently for yield.  With the progress of precision agriculture and the increasing availability of RTK equipped tractors in Southeast Alabama, the adoption of subsurface drip could become a viable tool in row crop production.  Proper installation and design of the system is vital.  Rotational work with cotton will continue to evaluate the long term results of subsurface drip irrigation and its impact on sustainable row crop production.