Hydroponic Agriculture for Sustainability and Accessibility
Deep Flow Technique System
Hydroponic agriculture offers increased sustainability compared to soil-based agriculture due to improved water and fertilizer use. Hydroponics also enables local production of food, cutting down on transportation-related costs and emissions. Unfortunately, high start-up costs and complexity of operation render hydroponics inaccessible for many. To ensure the maximum positive impact on food security Levo seeks solutions that increase the accessibility, affordability, and sustainability of hydroponic production.
Figure 1. Levo Deep Flow Technique System design. The figure is from Vega et al. 2023
Figure 2. Levo Deep Flow Technique systems growing peppers in Pignon, Haiti.
The figure is from Vega et al. 2023.
Levo started operations in rural Haiti where electricity and arable land are not consistently available. Therefore, Levo focused early research on the adaptation of nutrient film technique hydroponic systems to produce crops such as peppers without electricity. This required the use of intermittent manual circulation of systems instead of constant circulation powered by an electric pump. Levo developed simplified deep flow technique (DFT) systems to achieve this and conducted trials at the Connecticut Agricultural Experiment Station (CAES) Lockwood Farm and on Many Hands for Haiti’s campus in Pignon, Haiti to validate them. The results of this study were published in the peer-reviewed journal Agriculture & Food Security in 2023 and demonstrated that Levo’s DFT systems produced peppers as well as soil-based production systems and constantly circulated systems (Figure 1).
The Kratky System ADOPTION
Levo has now deployed this system type in diverse locations including Connecticut, Puerto Rico, central Haiti, Jamaica and Mexico (Figure 3). Due to its simplicity, the Kratky system is a powerful tool for increasing access to hydroponic production. A recent publication by researchers in Uganda stated that the Kratky system “has the potential to improve urban food production and availability especially in developing countries in a profitable manner.”
The Kratky system is a great tool for increasing food production, however, it was unknown how it compared in terms of production to DWC systems which include supplemental oxygen and monitoring of the nutrient solution. This question was especially interesting to Ben Lee, a former High School technician for Levo and the president of the hydroponics club at Cornell University. In a collaborative research effort, Levo and the Cornell Hydroponics club supported by Nicholas S. Kaczmar and Dr. Neil Mattson found surprising evidence that adding oxygen into Kratky systems did not improve lettuce yields. This led to a larger collaboration including the researchers Gustavo Garay-Rodriguez and Dr. Soledad Benitez Ponce at The Ohio State University and Shelley Durocher at The University of Connecticut.
This research confirmed that Kratky systems did not benefit from additional oxygenation, and actually produced yields that were similar to those produced by intensively monitored DWC systems (Figure 4). A manuscript describing this collaborative study is currently in the process of peer-review and is available in preprint form online. This collaboration will now look to see if this holds true for other crops in addition to lettuce.
Figure 3. A Kratky system design
Figure 4. Kratky systems at The Ohio State University (Wooster, OH)
Development of Natural Fertilizers
In 2011, scientists in Japan published a method to develop a hydroponic organic fertilizer using corn steep liquor as a main component. Levo earned a Connecticut Department of Agriculture Specialty Crop Block Grant starting in 2023 to use this technique to develop a natural fertilizer that would function well in Levo’s simplified systems. In the first growing season of trials, Levo successfully used natural fertilizer to grow lettuce, swiss chard and bell peppers (Figure 5). In collaboration with Dr. Jason White and Dr. Christian Dimpka at CAES as well as Shelley Durocher at the University of Connecticut, Levo is working on characterizing the nutrient contents of its successful fertilizer. Levo’s research team is also working on a streamlined process to produce this natural fertilizer commercially.
Figure 5. Levo team with pepper harvest from recent natural fertilizer trial
Organically fertilized hydroponic systems have improved disease resistance due to a more diverse community of microbes in the root systems which protect the plants from invaders. This plant microbiome has a role that is analogous to that of the human microbiome in promoting health. Therefore, Levo is collaborating with plant microbiome expert Dr. Soledad Benitez Ponce at The Ohio State University to investigate the microbiome of plants fertilized by our organic fertilizer. Levo has recently submitted samples for DNA sequencing and analysis of the bacterial communities in plant roots to the University of Connecticut Microbial Analysis, Resources, and Services Lab. We have been able to produce greens and fruiting crops in our systems without replacement of our nutrient solution by keeping the overall salt concentration low and periodically adding fertilizer. This has minimized the negative effects of nutrient imbalances so far and enabled us to conserve water and fertilizer. However, we do not have a good understanding of how individual nutrient concentrations change during the growth of different plants in our systems.
Levo in collaboration with Dr. Leigh Whittinghill and Dr. Jason White at CAES earned a 2024 Northeast Sustainable Agriculture Research and Education Program farmer grant to understand the nutrient dynamics in our systems. The data gained from this project will enable us to make precise nutrient additions for different crops. This will also help us to understand how yields and the health of different crops change without the complete replacement of the nutrient solution.