Comparison of SDI and Sprinkler Systems in Land Applying Swine Waste

Abstract

A Subsurface Drip Irrigation (SDI) system was installed in February 2007 on the Swine Unit of the Central Crops Research Station in Clayton, North Carolina to land apply anaerobic swine lagoon effluent on soybeans. Drip tape with 15 mil wall thickness rated at 2.20 L/H [0.58 gph] with emitter spacing of 0.30 meter [1.0 ft]) was installed at 0.96 m (38 in.) row spacing at 0.25 m (10 in.) depth in a Norfolk loamy sand soil. The SDI system covered about 0.2 ha (0.5 ac). The other half of the field was served by a “traditional” sprinkler irrigation system. The objective of the study was to compare relative environmental impacts of the two systems and to evaluate the technical feasibility of using an SDI system to land apply liquid swine manure. Environmental impact was assessed by collecting soil-water samples of chloride at 30 and 60 cm and collecting ammonia air samples after land application events. Technical feasibility of the SDI system was assessed by evaluating the distribution of liquid manure from the driplines and by comparing soybean yield to the traditional sprinkler system in addition to observing backflushing cycles and flow rates. There was no statistical difference in average chloride concentrations in soil-water samples. Total ammoniacal nitrogen air sample concentrations were lower in the SDI system, averaging about twenty percent of the concentration of samples taken from the sprinkler system area. Effluent spread about 0.30 meters laterally (one-direction) from the driplines. There was no statistical difference in yield by application method when combining over years.