Evaluation of old subsurface drip irrigation systems in Texas

A successful maintenance program may increase the longevity of Subsurface Drip Irrigation (SDI) systems. This study evaluated ten subsurface drip irrigation systems that have longevities between eight and twenty years. The system performance parameters: Christiansen’s Uniformity Coefficient (CUC) and Low Quartile Distribution Uniformity (DUlq) was assessed for ten SDI systems and their maintenance practices were documented. The longevity of the system may be related to the water quality of the aquifer. The aquifer does not present any major problem related to chemical compounds that can enhance clogging problems. The uniformity of the ten systems evaluated was greater than 79.3%. Maintenance practices among farmers were very similar. Most of the farmers flush their filters daily for at least 1.33 minutes and flush the manifolds once a year. Farmers inject sulfuric acid once a year lowering the pH to less than 3.5. Others use N-Phuric instead of the sulfuric acid. The sulfuric acid that most farmers use is 95% and they apply it at approximately 0.97 L h-1 (1 gal/10 acres). Some farmers inject chlorine every year, but others just every 7 years. The chlorine is Univar's sodium hypochlorite, which is 12% and they apply it at approximately 0.47 L h-1 (1 gal/20 acres). A good maintenance program and the use of good quality water may increase the longevity of the system.