S06 - Session P16 - Evaluation of organic substrates and irrigation rate for tomato production in the Dutch bucket hydroponic system

Authors: James Altland *, Teng Yang, Uttara Samarakoon

The Dutch bucket system is commonly used for high-wire crops such as tomatoes, peppers and cucumbers. In the US, perlite is the predominant growing media for this system, which causes problems due to excessive leaching and disposal after use. The objective of this research was to investigate the performance of three organic substrates under full or half irrigation rates with tomato ( Solanum lycopersicum 'Bigdena F1') as the model crop. The substrates evaluated were sphagnum peat, medium-texture pine bark, wood fiber, and perlite as the control. Plants were grown for five months in the Dutch bucket system. Irrigation was maintained to achieve a leachate rate of 40% to 50% for the vegetative phase and 20% to 30% for the reproductive phase among the full-irrigation treatment. Irrigation was maintained to achieve a leachate rate of 20% to 30% for the vegetative phase and 10% to 15% for the reproductive phase among the half-irrigation treatment. Leachate solution was collected once a week for EC, pH, leachate rate, fertilizer consumption and leachate mineral nutrient content measurements. Plant growth and yield parameters, and mineral nutrient content were measured. Peat leachate had higher EC and lower pH than other substrates throughout the study. Half-irrigation rate reduced leachate rate and fertilizer consumption in pine bark, wood fiber and peat, but not in perlite. Although irrigation rate did not affect total yield, individual fruit weight of half-irrigated peat and wood fiber grown tomato were significantly lower than that under full irrigation rate by 14.6% and 11.2%, respectively. In addition, fully irrigated peat had significantly higher total yield per plant than fully and half irrigated perlite. These results show that despite minor differences in some measured parameters, organic substrates can replace perlite for tomato grown in Dutch bucket hydroponic systems.