Drip irrigation emitter clogging in Dutch greenhouses as affected by methane and organic acids

• Autores: W.T. Runia, A.M.M. van der Burg, C. de Kreij
• Localización: Agricultural water management: an international journal, ISSN 0378-3774, Vol. 60, Nº. 2 (23 May), 2003, págs. 73-85
• Idioma: inglés
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• Resumen

  • It is believed that the serious clogging of drip irrigation emitters in the Dutch greenhouse industry is caused by methane-oxidising bacteria and/or organic acids used as anti-clogging agents. In this study greenhouses with moderate to severe emitter clogging have been examined. High methane concentrations¿¿up to 69 mg/l¿¿were found both in ground water (GW) and in the water from reverse osmosis (RO); however, in the fertiliser-mixing tanks (MTs), methane concentrations were <0.01 to 9 mg/l.

    In trials, a methane concentration of 0.11 mg/l in the fertiliser-mixing tank (MT), giving 0.08 mg/l at the emitter outlet, caused severe clogging of tube emitters and after prolonged exposure, also of labyrinth emitters. Slime in the emitter with `methane treatment' contaminated not only higher carbon and adenosine triphosphate, but also higher element concentrations than in the non-methane treatment. Biofouling increased the deposits of salts (scaling). To avoid emitter clogging, growers using ground water should carefully volatise the methane gas if it is present in the fertiliser-mixing tanks at concentrations higher than 0.01 mg/l, i.e. the detection limit.

    Organic acids, i.e. acetic acid and formic acid, were shown to increase the growth of Trichoderma, a fungus often isolated from emitter slime. Commercial anti-clogging agents containing organic acids were not effective in killing Trichoderma. It is likely that the carbon of the acids serve as a substrate for the micro-organisms. The use of anti-clogging agents without organic acids is advisable.

    Author Keywords: Clogging; Drip irrigation; Methane; Organic acids; Trichoderma