Principles of Nutrient and Water Management for Indoor Agriculture

Noah James Langenfeld (), Daniel Fernandez Pinto, James E. Faust, Royal Heins and Bruce Bugbee
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Noah James Langenfeld: Crop Physiology Laboratory, Utah State University, Logan, UT 84322, USA
Daniel Fernandez Pinto: Department of Chemistry, Universidad Nacional de Colombia, Bogotá 111321, Colombia
James E. Faust: Department of Plant and Environmental Sciences, Clemson University, Clemson, SC 29634, USA
Royal Heins: Crop Physiology Laboratory, Utah State University, Logan, UT 84322, USA
Bruce Bugbee: Crop Physiology Laboratory, Utah State University, Logan, UT 84322, USA

Sustainability, 2022, vol. 14, issue 16, 1-25

Abstract: Mass balance principles are a cornerstone of efficient fertilizer use and can be utilized to optimize plant nutrition without discarding or leaching solution. Here, we describe the maintenance of closed hydroponic and soilless substrate systems based on mass balance. Water removed by transpiration is restored with solution that replaces the nutrients that were taken up with the water. The concentration of nutrients in this refill/irrigation solution is determined by multiplying the optimal concentration of each nutrient in plant tissue by the water-use efficiency (WUE; ratio of dry mass to water transpired). Optimal leaf nutrient concentrations are well established, but WUE in controlled environments varies widely and is less well characterized. Elevated CO 2 increases photosynthesis and demand for nutrients, but partially closes stomata and reduces transpiration; so high CO 2 dramatically increases WUE. The concentration of the refill/irrigation solution must be adjusted to account for a two-fold range of WUE, from 3 g L −1 in ambient CO 2 in lower humidity, to 6 g L −1 in elevated CO 2 in higher humidity. WUE and nutrient requirements vary during the vegetative and reproductive stages of growth, and adjustment of the solution over the lifecycle can be beneficial. Measurement of solution electrical conductivity (EC) is helpful, but if the solution is appropriate, low EC usually means healthy plants and active nutrient uptake. The ammonium to nitrate ratio is critical to pH management. We have applied these principles across multiple species and environments to achieve long-term, steady-state nutrient concentrations with no discharge or leaching of solution.

Keywords: mass balance; hydroponics; nutrient management; water-use efficiency (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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