Stage-based Balance Analysis of Water, Nutrient, and Biomass Dynamics in a Hydroponic Tomato System

This study quantified the flows of water, nutrients, and biomass in a rockwool-based hydroponic tomato greenhouse under long-term cultivation conditions using a approach.The cultivation period was set to 240 days and was divided into five growth stages: establishment, vegetative growth, flowering and fruit set, harvesting, and a late stage.Stage-based fertigation volumes were determined according to common hydroponic management practices in Korea, and drainage was assumed to be 30% of the supplied nutrient solution.Over the entire cropping period, the total irrigation input amounted to 660.0 L•m -2 , of which 198.0 L•m -2 was discharged as drainage, while crop water uptake was 462.0 L•m -2 .Of the absorbed water, 446.6 L•m -2 (96.7%) was released to the atmosphere through transpiration, whereas only 15.4 L•m -2 (3.3%) was retained as water in the plant biomass.Nutrient flows were analyzed along the pathways of nutrient solution input, drainage discharge, and crop uptake, revealing that a substantial fraction of nutrients was lost from the system via drainage.Absorbed nutrients were allocated to fruits, vegetative tissues, and roots.Total fresh biomass production reached 16.43 kg•m -2 , with fruits accounting for 14.0 kg•m -2 , while non-harvestable aboveground biomass and roots accounted for 2.38 and 0.05 kg•m -2 , respectively.By linking biomass production with water and nutrient inputs through a framework, this study quantitatively elucidated resource use efficiency and loss structures in a hydroponic tomato cultivation system.The integrated analysis of water, nutrients, and biomass provides a systematic understanding of resource flows in hydroponic tomato greenhouse systems and offers a quantitative reference for optimizing fertigation practices.