Articles
Monitoring and control of nitrate in closed-loop hydroponics
Article number
1426_39
Pages
283 – 292
Language
English
Abstract
Hydroponics, coupled with nutrient solution recirculation, represents potential for improved resource utilization, reduced mineral fertilizer use, and reduced environmental impact.
However, closing a hydroponic loop may cause nutrient imbalance over time if nutrient feeding is not tuned to the system’s consumption.
Traditionally, nutrient solution monitoring has relied on electrical conductivity indicating its total strength, while individual nutrient levels have been measured offline, typically unable to support real-time process control.
In the presented study, near real-time nitrate monitoring was achieved based on a readily available optical sensor.
An at-line, auto-sampling and auto-diluting system was developed to mitigate drift and limited range.
A prototype monitored a recirculating nutrient solution during lettuce cultivation, in parallel with nitrate control solutions.
Automated analyses every 2-6 h over one month demonstrated measurement accuracies within ±3% of the measured value.
Coupled with a water and nutrient management system, nutrient stock solutions were automatically fed based on the continuous nitrate monitoring, maintaining nitrate levels within ±2% of the user-specified set-point.
Ultimately, a final version of the system was integrated into an advanced hydroponic crop cultivation facility and successfully used for nitrate monitoring and control.
However, closing a hydroponic loop may cause nutrient imbalance over time if nutrient feeding is not tuned to the system’s consumption.
Traditionally, nutrient solution monitoring has relied on electrical conductivity indicating its total strength, while individual nutrient levels have been measured offline, typically unable to support real-time process control.
In the presented study, near real-time nitrate monitoring was achieved based on a readily available optical sensor.
An at-line, auto-sampling and auto-diluting system was developed to mitigate drift and limited range.
A prototype monitored a recirculating nutrient solution during lettuce cultivation, in parallel with nitrate control solutions.
Automated analyses every 2-6 h over one month demonstrated measurement accuracies within ±3% of the measured value.
Coupled with a water and nutrient management system, nutrient stock solutions were automatically fed based on the continuous nitrate monitoring, maintaining nitrate levels within ±2% of the user-specified set-point.
Ultimately, a final version of the system was integrated into an advanced hydroponic crop cultivation facility and successfully used for nitrate monitoring and control.
Publication
Authors
Ø.M. Jakobsen, K.A. Kristiansen, M. Schiefloe, A.I.K. Jost
Keywords
hydroponics, NO3–, monitoring, control, real-time, nutrient solution, nitrogen
Groups involved
- Division Precision Horticulture and Engineering
- Division Greenhouse and Indoor Production Horticulture
- Working Group Nettings in Horticulture (subgroup of Protected Cultivation in Mild Winter Climates)
- Working Group Light in Horticulture
- Working Group Organic Greenhouse Horticulture
- Working Group Vegetable Grafting
- Working Group Modelling Plant Growth, Environmental Control, Greenhouse Environment
- Working Group Protected Cultivation, Nettings and Screens for Mild Climates
- Working Group Computational Fluid Dynamics in Agriculture
- Working Group Design and Automation in Integrated Indoor Production Systems
- Working Group Mechanization, Digitization, Sensing and Robotics
- Working Group Greenhouse Environment and Climate Control
- Division Landscape and Urban Horticulture
- Commission Agroecology and Organic Farming Systems
- Division Vegetables, Roots and Tubers
- Working Group Vertical Farming
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