Liquid Effluent from Poultry Waste Bioremediation as a Nutrient Source for Hydroponic Cucumber Production

Abstract

Fertilizer costs and increased awareness of point-source pollution are amplifying the pressures on farming, economics along with public demand for sustainable production methods and organically grown produce. Our research focuses on using effluent from thermophilic anaerobic digestion of poultry litter as an alternative fertilizer. Cucumbers (Cucumis sativus L.) were grown hydroponically using a bato bucket system to evaluate the effects of liquid effluent as a nutrient solution versus a commercial nutrient solution. Seeds of the beit alpha cultivar `Manar' were started in Horticubes and transplanted into buckets containing a perlite/coir media. The effluent fertilizer consisted of effluent diluted to the same ppm nitrogen found in the commercial fertilizer based on ammonium measured in the effluent. Hydroponic solutions were monitored twice a day to maintain a pH of 5.6-6.0. Fruit was harvested three times a week and graded on size and shape. Fruit of each grade were counted, weighed, and recorded. Average fruit weight and fruit number produced was statistically significant between the two fertilizer regimes with the commercial fruit, averaging 84 g compared to 75 g for effluent fruit. The effluent treatment produced a greater percentage of grade 1 fruit (33%) compared to the commercial treatment (26% grade 1 fruit). Thus, 74% of the commercial harvest was grade 2 or cull fruit compared to only 66% of the effluent harvest. Correlating grade with average fruit weight analysis identified statistical differences between treatments for the grade 1 fruit, but not the grade 2 or the culls. While effluent from thermophilic anaerobic digestion shows promise as an alternative hydroponic fertilizer, it is not better than the commercial fertilizer regime.