A real-time optical monitoring technology for sustainable hydroponic crop management

Abstract

Indoor vertical farming is crucial for solving future food challenges, especially in arable land-scarce countries. Among various techniques, hydroponics, which relies on nutrient-enriched water rather than soil to grow crops, has gained significant traction. However, optimizing crop yield while minimizing manual labor remains a challenge, particularly in automating crop health monitoring and nutrient replenishment. Currently, these processes are labor-intensive, prone to human error, and often subjective. While previous studies have utilized imaging techniques for detecting plant stress, monitoring chlorophyll content, and other health indicators, a fully integrated and automated system is still lacking. Current nutrient monitoring relies on tools such as electrical conductivity and pH meters, which provide only limited feedback on nutrient imbalances, inadequate to identify specific deficiencies or elemental concentrations accurately. To address these gaps, we propose a comprehensive monitoring system that combines two advanced modalities: imaging spectroscopy and laser-based elemental spectroscopy. This system includes imaging spectroscopes for monitoring crop health and a real-time nutrient analysis system based on laser-induced elemental spectroscopy for in situ quantitative chemical composition analysis of the nutrient solution. This comprehensive system will automate health monitoring and nutrient management, improving crop productivity and significantly reducing manual labor. The current prototype is optimized to swiftly identify crop growth stages, detect nutrient deficiencies, and quantify specific nutrient levels in green lettuce species. This advancement represents a significant step toward enhancing the efficiency and sustainability of indoor vertical farming.