Performance Evaluation of Micro-Irrigation Systems in Coconut Plantations

Abstract

Most of the coconut farmers in Sri Lanka are reluctant to adopt micro-irrigation systems, complaining about low performance. A field study was conducted to verify the claim. The performance was evaluated in two subunits at the inlet and distal end of two micro-irrigation systems with drippers and mini sprayers. The subunit at the inlet of the system with drippers showed a fair Emission Uniformity (78%) and all other tested subunits in both systems showed poor Emission Uniformity, falling below the 70% threshold set by the American Society of Agricultural Engineers. In the drip irrigation system, the increase of Emission Uniformity in the subunit at the distal end was approximately 33%. The increase of Emission Uniformity in all subunits of both systems was 4-6% after replacing the emitters with new emitters. The system with drippers showed severe clogging risk and the system with mini sprayers showed minor clogging risk. Despite the water being in the low clogging risk category, the mini sprayer exhibited the highest percent weight reduction (2%) after washing to remove clogging substances. The coefficient of manufacturer’s variation of the new drippers was in the marginal category of the classification. The Emitter Flow Variation of all the subunits were unacceptable level (>25%) with the existing drippers and mini sprayers. Only the subunit at the inlet of the drip irrigation system showed acceptable Emitter Flow Variation with new emitters. This study revealed that the low performance in both systems was due to emitter clogging and poor hydraulic design.