Articles
Consumption of NH4+ and NO3– by hydroponically cultivated lettuce at different NH4+:NO3– ratios
Article number
1426_34
Pages
243 – 250
Language
English
Abstract
Crop cultivation based on organic waste typically requires mineralization processes.
For nitrogen (N), ammonification and (partial) nitrification provide inorganic ammonium (NH4+) and nitrate (NO3–), and the resulting NH4+:NO3– ratio may vary with the raw material and mineralization process.
In closed-loop hydroponics, nutrient solution recirculation may improve resource utilization but cause nutrient imbalance over time if the nutrient resupply does not match the plant uptake.
Furthermore, the consumption of NH4+ versus NO3– will affect the nutrient solution NH4+:NO3– ratio, and elevated ratios may result in ammonium toxicity.
In this work, lettuce was cultivated as deep water culture using NH4+ and NO3– as sources of N, to investigate plant growth and N consumption over time.
Treatments varied in nutrient solution NH4+ to inorganic total-N ratio (NH4+:N), total strength, and the presence of NaCl.
Under the conditions tested, NH4+:N ratios of 0.00, 0.11, 0.22 and 0.44 mol mol‑1 did not result in statistically significant differences in shoot fresh weight.
However, 0.50 mol mol‑1 NH4+:N resulted in a 35% reduction of shoot fresh weight as compared to the maximum biomass obtained at 0.11 and 0.22 mol mol‑1. Investigations of consumption of inorganic N over time illustrated similar total-N consumption across treatments, irrespectively of whether NH4+ was depleted during the cultivation period or not.
Towards the end of the cultivation period, consumed NH4+ constituted 70-80% of the consumed total-N when the plants were cultivated at 0.50 mol mol‑1 NH4+:N compared to 50-60% at 0.11 or 0.22 mol mol‑1. For all treatments, the nutrient solution NH4+:N ratio decreased over time, even when starting at an unfavourable high ratio.
The results illustrate how plant cultivation conditions may change over time, relevant for crop cultivation strategies and the design and integration of upstream waste treatment for nutrient recycling in closed-loop hydroponics.
For nitrogen (N), ammonification and (partial) nitrification provide inorganic ammonium (NH4+) and nitrate (NO3–), and the resulting NH4+:NO3– ratio may vary with the raw material and mineralization process.
In closed-loop hydroponics, nutrient solution recirculation may improve resource utilization but cause nutrient imbalance over time if the nutrient resupply does not match the plant uptake.
Furthermore, the consumption of NH4+ versus NO3– will affect the nutrient solution NH4+:NO3– ratio, and elevated ratios may result in ammonium toxicity.
In this work, lettuce was cultivated as deep water culture using NH4+ and NO3– as sources of N, to investigate plant growth and N consumption over time.
Treatments varied in nutrient solution NH4+ to inorganic total-N ratio (NH4+:N), total strength, and the presence of NaCl.
Under the conditions tested, NH4+:N ratios of 0.00, 0.11, 0.22 and 0.44 mol mol‑1 did not result in statistically significant differences in shoot fresh weight.
However, 0.50 mol mol‑1 NH4+:N resulted in a 35% reduction of shoot fresh weight as compared to the maximum biomass obtained at 0.11 and 0.22 mol mol‑1. Investigations of consumption of inorganic N over time illustrated similar total-N consumption across treatments, irrespectively of whether NH4+ was depleted during the cultivation period or not.
Towards the end of the cultivation period, consumed NH4+ constituted 70-80% of the consumed total-N when the plants were cultivated at 0.50 mol mol‑1 NH4+:N compared to 50-60% at 0.11 or 0.22 mol mol‑1. For all treatments, the nutrient solution NH4+:N ratio decreased over time, even when starting at an unfavourable high ratio.
The results illustrate how plant cultivation conditions may change over time, relevant for crop cultivation strategies and the design and integration of upstream waste treatment for nutrient recycling in closed-loop hydroponics.
Publication
Authors
Ø.M. Jakobsen, M. Schiefloe, A. Gjindali, I. Karoliussen, A.I.K. Jost
Keywords
nitrogen utilization, ammonium, nitrate, consumption, toxicity, hydroponics
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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