Nutrient Dosing Framework for an Emission-Free Urban Hydroponic Production

Tae In Ahn,Sang Min Kim,Gyhye Yoo,Ju Young Lee,Jai-Eok Park,Hyoung Seok Kim,Je Hyeong Jung

doi:10.3389/fpls.2021.768717

Abstract

The urban hydroponic production system is accelerating industrialization in step with the potentials for reducing environmental impact. In contrast, establishing sustainable fertilizer dosing techniques still lags behind the pace of expansion of the system. The reproducibility of root-zone nutrient dynamics in the system is poorly understood, and managing nutrients has so far primarily relied on periodic discharge or dumping of highly concentrated nutrient solutions. Here, we assayed root-zone nutrient concentration changes using three possible nutrient dosing types. Three Brassica species were hydroponically cultivated in a controlled environment to apply the nutrient absorption and transpiration parameters to the simulation analysis. We found that nutrient dosing based on total ion concentration could provide more reproducible root-zone nutrient dynamics. Our findings highlight the nutrient absorption parameter domain in management practice. This simplifies conventional nutrient management into an optimization problem. Collectively, our framework can be extended to fertilizer-emission-free urban hydroponic production.

Highlights

Soil-based agriculture is facing substantial challenges such as the loss of arable land, water scarcity, nutrient leaching, and the carbon costs of transporting products
We found that nutrient dosing based on total ion concentration could provide more reproducible root-zone nutrient dynamics
We considered nutrient dosing methods, nutrient absorption kinetics, the transpiration rate, FIGURE 1 | The workflow of the theoretical and experimental analysis setup. (A) Nutrient absorption measurement of three Brassica species under a controlled environment. (B) Parameter estimation process under the simple hydroponic system model by using the progress curve analysis. (C) Stochastic manipulation of solar irradiance with a random walk generated cloud cover and subsequent transpiration rate variations in the simple hydroponic system model. (D) Three nutrient dosing processes in the simulation analysis. (E) Simulation analysis of the nutrient dosing effects on the nutrient variations and nutrient solution optimization

Summary

Introduction

Soil-based agriculture is facing substantial challenges such as the loss of arable land, water scarcity, nutrient leaching, and the carbon costs of transporting products. Under these circumstances, as a complementary solution, urban agriculture and vertical farming are currently being explored (Benke and Tomkins, 2017; O’Sullivan et al, 2019). The vertical farming system uses resources independently of the soil surface and expects optimal land use and environmental friendliness. There has been significant investment in the urban and vertical farming industry. Inspired by the potential of sustainability, researchers have started to explore urban vertical farming production (Seto and Ramankutty, 2016; Eshed and Lippman, 2019; Eldridge et al, 2020; Kwon et al, 2020; SharathKumar et al, 2020). At the same time, there are criticisms about technical pitfalls that prevent vertical farming from substantially contributing to environmental

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