Innovative Hydroponic Systems for Sustainable Agriculture

A special issue of Agriculture (ISSN 2077-0472). This special issue belongs to the section "Crop Production".

Deadline for manuscript submissions: 5 July 2024 | Viewed by 7375

Special Issue Editors


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Guest Editor
Hans-Ruthenberg-Institute for Tropical Agricultural Sciences, University of Hohenheim, Grabenstraße 13, 70599 Stuttgart, Germany
Interests: hydroponics; greenhouse technology, plant physiology; phytosociology; marginal water usage; plant-based wastewater treatment; desalination

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Guest Editor
Hans-Ruthenberg-Institute for Tropical Agricultural Sciences, University of Hohenheim, Grabenstraße 13, 70599 Stuttgart, Germany
Interests: plant physiology; ecophysiology; grasslands; skyfarming; root–shoot communication
Special Issues, Collections and Topics in MDPI journals
School of Civil and Environmental Engineering, Georgia Institute of Technology, 200 Bobby Dodd Way, Atlanta, GA 30332-0373, USA
Interests: high-density algal cultivation; crop protection; membrane technology for water/wastewater treatment and water and nutrient recycling for algal biomass production; life cycle analysis (LCA) of biofuel production
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

We are delighted to invite you to submit manuscripts for our upcoming Special Issue on hydroponic crop production. This Issue will explore the challenges and opportunities of maximizing nutrient and water use efficiency in hydroponic crop production, especially when using marginal water qualities. Efficient use of resources and sustainable management of low-quality water sources such as treated wastewater, nitrate-rich groundwater, or brackish water will contribute to expanding hydroponic cropping in regions where clean water is scarce. Moreover, this will limit the impacts on the aquatic environment and improve food security.

We warmly welcome your contributions from a range of disciplines, including agriculture, engineering and environmental sciences, to showcase cutting-edge research and innovative solutions. Original research articles, reviews and perspectives on the following topics are welcome for submission:

  • Water treatment and filtration strategies to improve the quality of marginal water for hydroponic crop production;
  • Sustainable water use strategies for hydroponic systems, including climate control for optimal transpiration and water use efficiency;
  • Innovative nutrient solution management systems for hydroponic crop production to enhance nutrient use efficiency and minimize the impact of undesirable contaminants;
  • Alternative techniques for monitoring and adjusting pH in hydroponic systems using marginal water sources;
  • Beneficial microorganisms to improve nutrient uptake and alleviate the negative effects of salinity on plant growth in hydroponic systems.

We encourage you to submit your research and share your insights with our readership.

Dr. Jörn Germer
Dr. Folkard Asch
Dr. Yongsheng Chen
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Agriculture is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • hydroponics
  • nutrient use efficiency
  • water use efficiency
  • marginal water qualities
  • water treatment
  • pH control
  • beneficial microorganisms

Published Papers (5 papers)

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Research

16 pages, 2442 KiB  
Article
Investigating the Impacts of Wastewaters on Lettuce (Lactuca sativa) Seed Germination and Growth
by Liam P. Reynolds, Vitória F. C. Leme and Paul C. Davidson
Agriculture 2024, 14(4), 608; https://doi.org/10.3390/agriculture14040608 - 12 Apr 2024
Viewed by 732
Abstract
There is an opportunity for agriculture to utilize the many different waste streams in our world and capitalize on what would otherwise be viewed as waste products. Hydrothermal liquefaction (HTL) is an emerging technology for converting wet biomass to bio-crude oil, while aquaponics [...] Read more.
There is an opportunity for agriculture to utilize the many different waste streams in our world and capitalize on what would otherwise be viewed as waste products. Hydrothermal liquefaction (HTL) is an emerging technology for converting wet biomass to bio-crude oil, while aquaponics is a practice tracing back to indigenous communities around the world; both technologies have the potential to sustainably provide the necessary nutrients for crop growth. Food systems worldwide are actively transitioning to address the many challenges of climate change in a sustainable and efficient manner. Urban agriculture (UA) has the potential to generate localized crops in densely populated areas year-round, but has its challenges, involving high capital requirements, especially for vertical farming and controlled-environment agriculture, and being energy intensive due to artificial lighting and fossil fuel-based synthetic fertilizers. This study investigated the potential for aquaponic and HTL effluents to be used in hydroponic systems through a seed germination screening experiment. Buttercrunch lettuce (Lactuca sativa L.) seeds were placed in Ziploc plastic bags on paper towels saturated with the wastewater treatments for 10 days while their total length of growth was routinely measured from the tip of the root to the tip of the cotyledons. The Chicago High School for Agricultural Sciences (CHSAS) aquaponic effluent with a 5.8× times higher nitrate concentration and 4.25× higher ammonia concentration outperformed the Bevier aquaponic effluent and improved any other source water it was combined with. Results also showed that seed germination was not inhibited in the presence of 2–8% solutions of hydrothermal liquefaction aqueous phase (HTL-AP), which performed on par with standard hydroponic fertilizer; solutions of a higher percentage, though, may lead to inhibitory effects in plants, and those of a lower percentage may not provide enough nutrients in the proper forms to sustain plant growth. However, the nutrient analyses revealed that there is still much to investigate regarding the combination of wastewaters to provide a complete, well-rounded, and sustainable source for hydroponic crop production. Full article
(This article belongs to the Special Issue Innovative Hydroponic Systems for Sustainable Agriculture)
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12 pages, 852 KiB  
Article
Wastewater Nutrient Recovery via Fungal and Nitrifying Bacteria Treatment
by Karla Lopez, Vitoria F. C. Leme, Marcin Warzecha and Paul C. Davidson
Agriculture 2024, 14(4), 580; https://doi.org/10.3390/agriculture14040580 - 6 Apr 2024
Viewed by 1282
Abstract
In efforts to reduce the consumption of fossil fuels and promote recycling biowaste, there is an interest in the production of post-hydrothermal liquefaction wastewater (HTL-AP) from the hydrothermal liquefaction (HTL) process that converts wet biomass into biocrude oil. This study explores ways of [...] Read more.
In efforts to reduce the consumption of fossil fuels and promote recycling biowaste, there is an interest in the production of post-hydrothermal liquefaction wastewater (HTL-AP) from the hydrothermal liquefaction (HTL) process that converts wet biomass into biocrude oil. This study explores ways of transforming potentially toxic HTL-AP into a fertilizer source for hydroponic cropping systems. This study specifically investigates the integration of the white-rot fungus Trametes versicolor with nitrifying bacteria (Nitrosomonas and Nitrobacter) to convert the organic nitrogen compounds into inorganic nitrogen while also producing the enzyme laccase, which has been shown to remove toxic compounds. This study aims to increase the concentration of nitrate-N to valorize wastewater as a suitable fertilizer by measuring several parameters, including laccase activity, pH, nitrate-N, and ammonia/ammonium-N concentrations, and analyzes interactions to optimize the conversion process. The data support the claim that the simultaneous inoculation of T. versicolor and nitrifying bacteria significantly increases nitrate-N concentrations in HTL-AP, as it increased by 17 times, or an increase of 32.69 mg/L. In addition, HTL-AP treated with T. versicolor and nitrifying bacteria reduced the treatment time by 120 h, highlighting a reduction in personnel time and energy consumption. Therefore, this research accentuates sustainability through fungal and bacterial treatments to develop eco-friendly hydroponic fertilizers. Future research should explore the potential of utilizing the combination of T. versicolor and nitrifying bacteria for the treatment of other industrial wastewaters. Full article
(This article belongs to the Special Issue Innovative Hydroponic Systems for Sustainable Agriculture)
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17 pages, 3472 KiB  
Article
Electrochemical In Situ Hydrogen Peroxide Production Can Reduce Microbial Load in Bioponic Nutrient Solutions Derived from Organic Waste
by Lukas Simon Kriem, Carsten Pietzka, Marc Beckett, Luisa Gärtling and Benjamin Wriedt
Agriculture 2023, 13(11), 2122; https://doi.org/10.3390/agriculture13112122 - 10 Nov 2023
Viewed by 1233
Abstract
Technological advancement in recent decades has allowed for crop cultivation in soilless controlled environments, known as hydroponics, and this is being employed in an increasing number of factories worldwide. With continued local and regional disruptions in the supply chain to provide mineral fertilizers, [...] Read more.
Technological advancement in recent decades has allowed for crop cultivation in soilless controlled environments, known as hydroponics, and this is being employed in an increasing number of factories worldwide. With continued local and regional disruptions in the supply chain to provide mineral fertilizers, new pathways to generate nutrient solutions are being developed. One potential approach is the recovery of nutrients from organic waste and wastewater using bioponics. Bioponics refers to the biological mineralization of organic residues through processes such as anaerobic and aerobic digestion and the use of such organically produced nutrient solutions in hydroponic systems. However, without disinfection of the nutrient solution, the high microbial loads increase the risk of pathogens affecting plant and consumer health. In this work, electrochemical hydrogen peroxide (H2O2) demonstrated success in reducing microbial loads. Different scenarios of application were considered: (1) variation in the H2O2 concentration in the nutrient solution by dosing H2O2 from ex situ electrochemical production, (2) variation in the dosing time-dependent reaction between the nutrient solution and H2O2 produced ex situ, and (3) the in situ production of H2O2 of the organic nutrient solution. The highest tested H2O2 concentration of 200 mg L−1 showed a microbial load reduction of bacteria at 93.3% and of fungi at 81.2%. However, the in situ production showed the highest reduction rate for bacteria and fungi in bioponic nutrient solutions, where longer reaction times also impact microbial concentrations in situ. Final microbial reductions of 97.8% for bacteria and of 99.1% for fungi were determined after a H2O2 production time of 60 min. Overall, our results show that electrochemical H2O2 production can be used to disinfect bioponic nutrient solutions, and the production cell can be implemented in bioponic systems in situ. Full article
(This article belongs to the Special Issue Innovative Hydroponic Systems for Sustainable Agriculture)
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15 pages, 632 KiB  
Article
Water Availability in Pumice, Coir, and Perlite Substrates Regulates Grapevine Growth and Grape Physicochemical Characteristics in Soilless Cultivation of Sugraone and Prime Cultivars (Vitis vinifera L.)
by Emmanouil Kontaxakis, Dimitrios Papadimitriou, Ioannis Daliakopoulos, Ioannis Sabathianakis, Andriana Stavropoulou and Thrassyvoulos Manios
Agriculture 2023, 13(9), 1690; https://doi.org/10.3390/agriculture13091690 - 27 Aug 2023
Viewed by 1393
Abstract
Table grape production in soilless cultivation under a controlled environment is a promising solution that addresses many of the challenges of grapevine cultivation, such as factors affecting the quantity and quality of table grape production, cultivation cost, pest management, soil degradation, soil-borne diseases, [...] Read more.
Table grape production in soilless cultivation under a controlled environment is a promising solution that addresses many of the challenges of grapevine cultivation, such as factors affecting the quantity and quality of table grape production, cultivation cost, pest management, soil degradation, soil-borne diseases, and adaptation to climate change. However, due to limited knowledge, investigation of many factors is required to effectively implement soilless cultivation, among which are the substrate’s physical-hydraulic properties and suitability for grape production. In this context, we investigate the impact of the properties of organic (coir dust) and mineral (perlite, pumice) substrates and their blend (perlite:coir) on grapevine growth and grape physicochemical characteristics of Sugraone (Superior Seedless) and Prime cultivars. Perlite substrate was the best in qualitative and quantitative production characteristics, whereas pumice substrate proved unsuitable for soilless vine cultivation. Coir and perlite:coir substrates, due to their increased ability to retain moisture, improved plant nutrition and grape quality but delayed ripening. For effective soilless cultivation of grapevines and table grape production, substrates must have the ability to maintain sufficient but not excessive moisture, suitable for supporting physiological processes and plant nutrition, resulting in smooth growth and production. Full article
(This article belongs to the Special Issue Innovative Hydroponic Systems for Sustainable Agriculture)
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21 pages, 4047 KiB  
Article
Growth of Lettuce in Hydroponics Fed with Aerobic- and Anaerobic–Aerobic-Treated Domestic Wastewater
by Jörn Germer, Christian Brandt, Frank Rasche, Thomas Dockhorn and Alexa Bliedung
Agriculture 2023, 13(8), 1529; https://doi.org/10.3390/agriculture13081529 - 1 Aug 2023
Cited by 4 | Viewed by 1846
Abstract
Reusing water and nutrients from municipal wastewater can conserve resources and reduce wastewater treatment costs. In this study, the suitability of different qualities of treated wastewater for plant production in a hydroponic flow-through system was investigated. Lettuce (Lactuca sativa L.) was grown [...] Read more.
Reusing water and nutrients from municipal wastewater can conserve resources and reduce wastewater treatment costs. In this study, the suitability of different qualities of treated wastewater for plant production in a hydroponic flow-through system was investigated. Lettuce (Lactuca sativa L.) was grown in hydroponic lines fed with treated wastewater, i.e., conventional effluent from aerobic wastewater treatment by the activated sludge process (CE), ozonised CE (CEO), anaerobically pre-treated and nitrified wastewater (AN) and biological activated carbon filtered AN (ANC) in comparison with a modified Hoagland nutrient solution. In CEO, AN and ANC, the lettuce reached a similar weight and elemental composition as that in HS. The low N and P concentrations in CE and CEO were quickly depleted, resulting in limited plant development at the ends of these lines. The lower water content in the CE shoots was probably related to hypoxia that occurred at higher temperatures. In the CEO line, this condition did not arise due to the constant decay of O3. At lower temperatures, the CEO shoot dry weight was 90% higher than that in CE. This was possibly an effect of residual ozone and/or oxygen supersaturation. AN produced the highest yield, while carbon filtration lowered the content of cations in ANC, inducing deficiency of Fe > Mn > Cu > Zn > K. Coupling wastewater treatment with hydroponics allows for efficient nutrient recovery, and thus could reduce the energy and reactor volume needed for N and P elimination. Full article
(This article belongs to the Special Issue Innovative Hydroponic Systems for Sustainable Agriculture)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: Impact of root temperature on growth and photosynthesis in rice
Authors: Pieters, A.
Affiliation: Hans-Ruthenberg-Institute for Tropical Agricultural Sciences, University of Hohenheim, Grabenstraße 13, 70599 Stuttgart, German

Title: Accumulation and fate of micropollutants in lettuce irrigated with treated domestic waste water
Authors: Germer, J.
Affiliation: Hans-Ruthenberg-Institute for Tropical Agricultural Sciences, University of Hohenheim, Grabenstraße 13, 70599 Stuttgart, German

Title: The effects of select microorganisms on the salt tolerance of hydroponically-grown tomatoes
Authors: Giesting, G.
Affiliation: Hans-Ruthenberg-Institute for Tropical Agricultural Sciences, University of Hohenheim, Grabenstraße 13, 70599 Stuttgart, German

Title: Effect of vapor pressure deficit and different levels of continues ammonium applications on biomass production, enzyme activity and nutrient uptake and allocation of a hydroponic tomato crop
Authors: Detering, T.
Affiliation: Hans-Ruthenberg-Institute for Tropical Agricultural Sciences, University of Hohenheim, Grabenstraße 13, 70599 Stuttgart, Germany

Title: Effect of salinity on plant growth and nutrient uptake in two genotypes of tomato and cucumber under two relative humidity levels
Authors: Puppala, H. K.
Affiliation: Hans-Ruthenberg-Institute for Tropical Agricultural Sciences, University of Hohenheim, Grabenstraße 13, 70599 Stuttgart, Germany

Title: Water treatment and filtration strategies to improve the quality of marginal water for hydroponic crop production
Authors: Sybille Karwat
Affiliation: Technische Universität Braunschweig

Title: Plant growth-promoting microorganisms - mechanisms and potentials for hydroponic systems
Authors: Castiglione, S.
Affiliation: University of Salerno

Title: Automatic pH control in hydroponic systems by ammonium addition using 3D-printed pump arrays
Authors: Jörn Germer
Affiliation: Hans-Ruthenberg-Institute for Tropical Agricultural Sciences, University of Hohenheim, Grabenstraße 13, 70599 Stuttgart, Germany

Title: Nutrient depletion in hydroponic culture - causes and implications
Authors: Shenker, M.
Affiliation: Hebrew University of Jerusalem

Title: Innovative irrigation management approaches for smart and sustainable agriculture
Authors: Suay, R.
Affiliation: University of Alicante / University of Valencia

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