2018 ASHS Annual Conference

Biofilms are commonly found on the inside surface of pipes and irrigation emitters. Biofilms consist on bacteria attached to surfaces and enclosed in protective matrix of polysaccharide. Biofilms can accumulate and clog irrigation systems and result in uneven irrigation. The objective of the experiment was to determine if pipe material and irrigation frequency can affect biofilm accumulation. The experiment was a full factorial in which the factors were irrigation frequency (sub factors: continuous flow, 30 s every 9.5 min, and 2 min twice a day) and pipe material [polyethylene (PE) and polyvinyl chloride (PVC)]. Nutrient solutions were prepared using pond water and 200 mg·L^-1 N. The solutions were recirculated for four weeks and the experiment was conducted twice. Total aerobic bacteria attached to the surface and biofilm dry biomass were measured as indicators of biofilm accumulation. Biofilm differed by pipe materials at the different irrigation frequencies. Biofilm in PVC pipes was more abundant than in PE pipes when the nutrient solution flowed continuously or 30 s every 9.5 min. Biofilm in both pipe materials at irrigated for 2 min twice a day had the lowest amount of biofilm. These results indicate that using PE can delay the accumulation of biofilm in irrigation pipes within a four week-period and may reduce the risk of clogging.