SOIL HEALTH AND ENVIRONMENTAL IMPACTS OF SALTWATER INTRUSION IN AGRICULTURAL AREAS AND MITIGATION STRATEGIES

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: ACTIVE
• Funding Source: AFRI COMPETITIVE GRANT
• Reporting Frequency: Annual
• Accession No.: 1022203
• Grant No.: 2020-67019-31163
• Cumulative Award Amt.: $497,315.00
• Proposal No.: 2019-06527
• Project Start Date: Jul 1, 2020
• Project End Date: Jun 30, 2026
• Grant Year: 2020
• Program Code: [A1401]- Foundational Program: Soil Health

Recipient Organization
UNIVERSITY OF FLORIDA
G022 MCCARTY HALL
GAINESVILLE,FL 32611

Performing Department
Ag & Bio Engineering

Non Technical Summary
About 40% of the global population lives within 60 miles fromthecoast and roughly three-fourths of the large cities around the world are along the coastlines. Climate change accelerates the sea level rise, saltwater intrusion and storm surge causing flooding of soils with saltwater, whichin turn will have an immediateand serious impact on agricultural productivity and food security.As sea-level rise (SLR) continues, much of the attention of impact has been on the saltwater intrusion (SWI) of groundwater and the threat it poses on the freshwater resources in coastal regions. However, limited attention is given to the impact of the landward movement of saltwater by surface and/or groundwater connections that can influence the salinity of soil in agricultural fields. The impact of SLR is also on the salinization of drainage ways, including natural as well as man-made canals and ditches, which in turn impact soil health and agricultural productivity as well. The land-use changes such as draining the wetlands for cultivation results in lowering the elevation of the landscape, and more inland water connection through drainage ditches to maintain the soil suitable for cultivation. These changes will contribute to an increased riskof salinization of inland surface water and the soil.SWI is a critical issue in Florida, which is surrounded by seawater on three sides, which heavily depends on shallow aquifers as freshwater sources for drinking and irrigation. Chloride concentration in seawater is 19,400 mg/L, therefore, SWI of the slightest scale can exceed the EPA's standard chloride concentration of 250 mg/L in potable water. Studies by the US Geological Survey confirmed a significant increase in chloride concentrations between 1985 to 2000 in shallow and deep aquifer water samples in the southwest and southeast Florida.As sea-level rise (SLR) continues, salinity due to saltwater intrusion (SWI) will impact soil health and agricultural production. As such the significant threats of salinity necessitate more work to be done to better understand its impacts on soil health indicator parameters and associated functional ecosystem processes. This is even of greater importance in areas, such as South Florida, where the surface and groundwater resources are hydrologically connected due to the shallow and highly permeable limestone soils. A better understanding of the impacts of salinity due to SWI on soil health is critical to design effective mitigation strategies. Soil health status could be evaluated using a set of measurable physical, chemical, biological, and hydrological attributes. Healthy soil has multifaceted benefits to enhance agricultural productivity, i.e. regulates the flow of water, serves as a source and sink of nutrients, and provides optimal biological and chemical conditions for the transformation of nutrients. This research will be conducted using seawater and multi-pronged approaches: column studies, landscape monitoring, and modeling for in-depth investigation of the impacts of SWI on soil health, nutrient transformations in soil and soil water, and greenhouse gas (GHG) emissions with a focus on agricultural soils. Different management strategies, such as the application of engineered biochar, salt repelling hydrogel, and gypsum, and organic mulch will be evaluated to mitigate the negative effects of SWI. Improved understanding of the processes and impact of SWI on soil health will assist in guiding policy and decisions regarding best management practices to mitigate the impacts of SWI.

Animal Health Component

35%

Research Effort Categories

Basic

50%

Applied

35%

Developmental

15%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
102	0110	2000	25%
111	0210	2050	25%
103	0199	1070	50%

Knowledge Area
103 - Management of Saline and Sodic Soils and Salinity; 102 - Soil, Plant, Water, Nutrient Relationships; 111 - Conservation and Efficient Use of Water;

Subject Of Investigation
0110 - Soil; 0210 - Water resources; 0199 - Soil and land, general;

Field Of Science
2050 - Hydrology; 1070 - Ecology; 2000 - Chemistry;

Keywords

engineered biochar

gypsum

hydrogel

hydrologic model

salinity

soil mulch

Goals / Objectives
The long-term goal of this research project is to develop novel and realistic soil and water management strategies that mitigate the effects of salinity on soil health and the environment. Our overall objective is to identify the impacts of saltwater intrusion on soil health and develop and test potentials of novel soil amendments to mitigate the impacts of salinity due to SWI.The rationale for this project is that the new information and soil amendment technologies will provide critical knowledge that would lead to a bigger and integrated effort to mitigate the impacts of salinity and SWI on agricultural soils. This project has assembled a team of multi-disciplinary scientists, who are well-positioned to lead the project and address its objectives. The overall objective of the project will be attained by pursuing the following three specific objectives:Specific objective 1: Determine the impacts of saltwater intrusion on soil health, nutrients transformation in soil and soil water, and greenhouse gas emission.Specific objective 2: Develop and test the potentials of novel soil amendments (engineered biochar, salt repelling hydrogel, gypsum, and organic mulch) in mitigating the impacts of salinity due to SWI on soil health.Specific objective 3: Model the impacts of SWI on soil hydrology at different scales and develop decision support tools.We expect that, upon the successful completion of this project, we will have developed novel soil amendments that can be effectively used to mitigate the negative impacts of salinity due to SWI on soil health and the environment.

Project Methods
The execution of this project will require a multidisciplinary and multifaceted approach. There are four major interconnected phases, i.e. controlled studies, field monitoring and modeling, mitigation strategies, and integration of results of all phases as described below:In controlled studies, we will investigate the changes in soil health indicator parameters (physical, chemical, biological, and hydrological) in response to different durations of saturation by saltwater. The results of this study will provide much needed information on the buildup of soil salinity and changes in soil health parameters that impact crop production. Subsequently, these soils will be leached by freshwater to determine how many cycles of freshwater flooding or leaching is needed to remove the salts from the soil profile to restore the desirable properties of the soil that was damaged by saltwater. We will also examine the changes in greenhouse gasses emission rates from the soil during saltwater flooding and subsequent freshwater leaching cycles. Therefore, this project will address the impact of SWI, in part due to Sea Level Rise, which in turn is impacted by an accelerated rate of climate change on soil quality and productivity. Furthermore, we will also evaluate the potential for changes in GHG emissions from agricultural soils impacted by saltwater flooding due to projected enhanced storm surges as an outcome of an accelerated rate of SLR in vulnerable areas in the coastal regions.The second pathway of deterioration of soil quality and productivity is due to the salinization of drainage canals and shallow groundwater, which in turn cases flooded conditions on agricultural soils after storm events. We will study this problem by collecting soil and groundwater samples from the coastal area into the field at various distances. Multiple years of sampling both soil and water across transacts of different distances will give much needed information on changes in soil salinity from the canal into inland over time.Using data from controlled studies and field monitoring we will develop a modeling framework to simulate the effects of salinity on soil health indicator parameters especially soil hydraulic properties, nutrient adsorption/desorption, and transport at different scales.Most importantly, for practice significance, it is highly important to develop potential mitigation strategies to minimize the negative impacts of salinity on soil health and productivity. In this study, we will evaluate the effects of amending saltwater impacted soil with gypsum, biochar or hydrogel. The latter two amendments will be specially developed for this study which can exhibit high impact to mitigate the negative effects of saltwater flooding. These products are produced using agricultural wastes such as bagasse, wood chips, cottonwood, sorghum, peanut hulls, or cow manure. Biochar is produced by slow pyrolysis, i.e. an optimal combination of temperature and oxygen-free combustion. The hydrogel can be produced by a special process using lignin such as wasteproduced from a paper mill or other agricultural waste materials. This process will develop hydrogel with high cation exchange capacity and swelling characteristics that are important for high salt tolerance.

Progress 07/01/23 to 06/30/24

Outputs
Target Audience:The project aims to reach a diverse audience, including researchers, graduate students, extension specialists, and the general public. While this project is 100% research and extension and outreach was were not originally part of the project scope, extension agents--who bridge the gap between research and practical application--we are now closely working with them enhance their outreach efforts. Changes/Problems:The groundwater modeling work to evaluate saltwater intrusion and its impacts on agriculture and water quality took more time and effort than anticipated, but we are now on track to complete the task. This delay was partly due to a potential Ph.D. student opting to finish with an MS degree, which required adjustments in staffing, with other personnel taking on specialized tasks and additional training. Labor shortages and rising minimum wages further strained the project, as the initial budget for OPS personnel proved insufficient. Strategic adjustments were made to overcome these challenges. What opportunities for training and professional development has the project provided?Through the project, several individuals received training that enhanced their professional development. The trained participants included researchers, postdoctoral associates, visiting scholars, and OPS personnel. They were engaged in comprehensive training covering multidisciplinary concepts such as data collection, analysis, and presenting at scientific conferences. This training was facilitated through one-on-one mentorship, in-depth discussions, and regular interactions with the project team. How have the results been disseminated to communities of interest?The project team has been active in sharing findings with a wide range of audiences at scientific conferences, as well as local and regional meetings. This dissemination included the publication of two peer-reviewed articles in reputable journals, significantly contributing to the existing literature. The team also delivered four presentations at professional conferences, including the American Society of Agricultural and Biological Engineers (ASABE) Annual International Meeting in Anaheim, California. What do you plan to do during the next reporting period to accomplish the goals?We are currently working on the landscape-scale modeling component of the project, building on insights from the greenhouse study to evaluate saltwater intrusion and its potential risks to water quality and agricultural soils in South Florida. Additionally, several samples, including those for microbial biomass, are still pending analysis.

Impacts
What was accomplished under these goals? Soil Amendment Experiment: During this reporting period, a series of colmun experiments were conducted to evaluate the effectiveness of different soil amendemntes in mitigtating salinity and flooding impacts on Krome and Biscayne soils from south Florida. Treatemtns include biochar, gypsum, compost, and hydrogel applications at 3%, and 1.5% (w/w) and control. Soil and amendment were mixed thoroughly and packed into PVC columns (61cm long and 15.24cm diameter). Porwaters samples were collected periodically at htree depths. Two large IBC tanks with a capacity of 1040L were used for the experiment. Each container was filled either seaswater or freshwater and columns were left under saturated conditions for 7 days. Sub-hourly soil moisture, temperature, and electrical conductivity data were collected from three depths using sensors connected to a data logger. Greenhouse gas samples were collected on days 1 and 7 of flooding and analyzed for carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). At the end of the exsperiment soil samples were collected for lab analysis of selected parameters.

Publications

• Type: Journal Articles Status: Published Year Published: 2024 Citation: Hailegnaw, N.S., H.K. Bayabil, Y. Li, and B. Gao. 2024. Seawater flooding of calcareous soils: Implications for trace and alkaline metals mobility. Science of the Total Environment 927, 172210. https://doi.org/10.1016/j.scitotenv.2024.172210
• Type: Journal Articles Status: Published Year Published: 2024 Citation: Hailegnaw, NS., H.K Bayabil, Y.C Li. 2023. Environmental implications of salinity and flooding induced changes in porewater nitrogen and phosphorous dynamics. Environmental Pollutants and Bioavailability. 35(1) 2269314. https://doi.org/10.1080/26395940.2023.2269314
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2024 Citation: Bayabil, H.K., N. Hailegnaw, G. Awoke, M. Berihun, G. Kefelegn, and Y. Li. 2024. Impacts of Seawater Flooding on Soil: Insights from Greenhouse Experiment and Modeling. Florida Section American Society of Agricultural and Biological Engineers (FLASABE) Annual Meeting. Jensen Beach, FL. June 12-15, 2024. Oral presentation.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2024 Citation: G. Kefelegn, N. Hailegnaw, G. Awoke, M. Berihun, and Bayabil, H.K. Mitigating flooding and salinity impacts using soil amendments: Nutrient dynamics and greenhouse gas emissions, American Society of Agricultural and Biological Engineers (ASABE) Annual Meeting. Jensen Beach, FL. June 12-15, 2024. Oral Presentation.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2024 Citation: Awoke, G.W., N. Hailegnaw, M. Berihun, and Bayabil, H.K. Simulating Solute Transport from Saturated Soils Using Numerical and Machine Learning Models. Florida Section American Society of Agricultural and Biological Engineers (FLASABE) Annual Meeting. Jensen Beach, FL. June 12-15, 2024. Oral presentation.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2024 Citation: Berihun, M.L., Bayabil, H.K., and Chebud, Y. Examining the impact of sea-level rise scenarios on the dynamics of groundwater quantity and quality in Floridas coastal areas. Florida Section American Society of Agricultural and Biological Engineers (FLASABE) Annual Meeting. Jensen Beach, FL. June 12-15, 2024. Oral presentation.

Progress 07/01/22 to 06/30/23

Outputs
Target Audience:Our research appeals to a diverse and multifaceted audience, including researchers and scientists who seek to deepen their understanding of the subject matter and graduate students. Despite extension work not being initially part of the project scope, extension agents, who bridge the gap between research and practical application, are an integral part of our target audience, benefiting from insights that can inform their outreach efforts. Beyond the academic and professional realm, our research also resonates with the general public, providing accessible knowledge and fostering a broader understanding of the topics we explore. Changes/Problems:The project encountered a situation where a potential Ph.D. student had to complete his program with an MS degree. Given the project timeline, recruiting another graduate student was not feasible. This shift necessitated adjustments in project staffing, and other personnel were required to take on specialized project tasks. This adjustment process demanded additional training and resource reallocation to ensure the smooth continuation of project activities. Furthermore, labor shortages and increases in minimum wages presented ongoing challenges for the project. The initial budget allocation for OPS personnel in the project proposal proved insufficient compared to the current market conditions, prompting the need for strategic adjustments and resource management to address staffing needs effectively. What opportunities for training and professional development has the project provided?During this reporting period, the project provided valuable training and professional development opportunities. One graduate student successfully graduated with a Master of Science (MS) degree, contributing to this project. His research delved into "Salinity Mitigation Strategies for Salt-Affected Soils," offering insights into potential solutions for soil salinity issues. Furthermore, the project involved the active participation of two OPS personnel and one research coordinator, who engaged in comprehensive training encompassing multidisciplinary concepts. This training was facilitated through one-to-one mentorship sessions, in-depth discussions, and regular interactions with the project team. Additionally, graduate students and research technicians received hands-on training in various crucial aspects, including conducting thorough literature reviews, crafting informative factsheets, mastering data analysis techniques, preparing manuscripts for peer-reviewed journal publications, and delivering presentations on project findings at professional conferences. How have the results been disseminated to communities of interest?The project's findings were effectively disseminated to various audiences, including the scientific community and other stakeholders. This dissemination included publishing three peer-reviewed articles in reputable journals, significantly contributing to the existing knowledge in relevant fields. Additionally, a non-refereed paper was published to reach a broader audience and ensure the accessibility of project insights. The project team also actively participated in professional conferences, delivering four presentations. These presentations were made at prestigious events such as the American Society of Agricultural and Biological Engineers (ASABE) Annual International Meeting, providing a platform for sharing project results with experts and peers in the field. What do you plan to do during the next reporting period to accomplish the goals?In the upcoming reporting period, the project has several key objectives to achieve. First and foremost, the team aims to finalize the greenhouse column experiments, focusing on using seawater to assess the effectiveness of various soil mitigation strategies, including hydrogel, biochar, organic mulch, and gypsum. Additionally, ongoing data analysis efforts will continue, allowing for a comprehensive understanding of project outcomes. Manuscript preparation for peer-reviewed publication will be a priority, ensuring that the research contributes to the scientific community's body of knowledge. The project will also develop a groundwater model, leveraging long-term data from groundwater monitoring wells provided by the South Florida Water Management District and the Department of Environmental Resources Management (DERM) of Miami-Dade County. This model will simulate sea level and climate change impacts on saltwater intrusion, furthering our understanding of this critical environmental issue. The team aims to submit at least three refereed manuscripts for journal publication and present project results at two conferences and/or professional meetings.

Impacts
What was accomplished under these goals? Baseline Experiment Progress:Our ongoing baseline greenhouse column experiments were continued during this reporting period. These experiments play a pivotal role in building a foundational understanding of how salinity and salt buildup impact various critical aspects of soil health parameters. We concentrated our efforts on two predominant soil types in South Florida, Krome and Biscayne soils, to provide comprehensive insights into the region's unique soil dynamics. In these experiments, soils were flooded with seawater and freshwater for varying durations. This allowed us to simulate real scenarios and assess the resulting changes in soil properties. We employed advanced sensor technology and a data logger system to collect precise data. These tools enabled us to precisely and consistently monitor critical parameters such as soil moisture, electrical conductivity, and temperature. Our data collection efforts extended beyond physical measurements. We collected time-series pore water samples from each experiment, subjecting them to thorough analysis to better understand nutrient dynamics and other essential water quality parameters. Furthermore, we gathered soil samples that will undergo lab analysis to evaluate microbial biomass, shedding light on the impacts of salinity on soil microbes. Additionally, we conducted greenhouse gas flux measurements, focusing on three significant gases: carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). This aspect of the research is invaluable in understanding the environmental implications of salinity-induced changes in soil health. Greenhouse Gas Analysis:A total of 360 GHG samples collected between 2021 and 2022 were analyzed. Initial findings from 2021 indicated the need for additional sampling points to enhance flux detection limits due to the presence of low fluxes. There were measurable N2O fluxes detected, most likely due to incomplete denitrification. In 2021, about 2/3 of the samples displayed double peaks for CH4. To accurately quantify CH4 concentrations and fluxes, these peaks were re-integrated to isolate the mysterious peak and CH4 peaks. It is possible that the mysterious peak could becarbon monoxide (CO), but additional testingwould be required to confirm the makeup of this mysterious peak, but this is beyond the scope of this project. In 2022, we switched to a new GC, which has a pressure peak elute at the same time as CO and is unable to measure CO. Soil Amendment Experiment Progress: We made significant strides in our soil amendment experiments, which hold promise in developing strategies tomitigate the adverse effects of soil salinity. Leveraging developed, tested, and optimized hydrogel technology and other established soil amendments such as biochar, gypsum, and mulch, we have conducted a series of experiments to assess their effectiveness. In these experiments, soils were exposed to prolonged seawater inundation for seven days. Our data collection process mirrored that of the baseline experiments, encompassing soil moisture measurements, electrical conductivity, and temperature. These parameters allowed us to track changes in soil conditions and salinity levels over time. Porewater analysis and soil sample collection were integral components of this experiment, enabling us to evaluate the impact of soil amendments on nutrient dynamics and other water quality parameters. Additionally, we continued to measure greenhouse gas fluxes, providing critical insights into how these amendments influence greenhouse gas emissions within the soil environment. As our research progresses, analyzing these collected samples and data will be pivotal in assessing the efficacy of soil amendments in alleviating soil salinity, potentially offering sustainable solutions to address this pressing environmental concern.

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2023 Citation: Hailegnaw, N.S., H. K Bayabil, F. Teshome, Y. Li, and B. Gao. 2023. Impacts of flooding induced salinity on soil hydrology and nutrient leaching from a poorly drained marl soil. 2023 ASABE Annual International Meeting. Paper Number: 2300377.
• Type: Conference Papers and Presentations Status: Published Year Published: 2023 Citation: Tefera, B.B., H.K. Bayabil, B. Gao, Y. Li and Y. Chebud. 2022. Spatial Analysis of Groundwater Level and Salinity of the Coastal Aquifer in South Florida. ASA, CSSA, SSSA International Annual Meeting. Virtual. Nov 6-9, 2022. Poster presentation.
• Type: Journal Articles Status: Published Year Published: 2022 Citation: Bayabil, H.K., F.T. Teshome, N.S. Hailegnaw, J. Zhang, and Y. Li. 2022. Changes in Soil Evaporation Stages with an Organic Fertilizer. Experimental Results 3, E27. https://doi.org/10.1017/exp.2022.25
• Type: Journal Articles Status: Published Year Published: 2022 Citation: Tefera B.B., H.K. Bayabil, Z. Tong, F.T. Teshome, P. Wenbo, Y.C. Li, N.S. Hailegnaw, and B. Gao. 2022. Using liquefied biomass hydrogel to mitigate salinity in salt-affected soils. Chemosphere 309. 136480. https://doi.org/10.1016/j.chemosphere.2022.136480.
• Type: Journal Articles Status: Published Year Published: 2022 Citation: Bayabil, H.K., F.T. Teshome, and Y.C. Li. 2022. Emerging Contaminants in Soil and Water. Front. Environ. Sci. 10:873499. https://doi.org/10.3389/fenvs.2022.873499
• Type: Conference Papers and Presentations Status: Other Year Published: 2023 Citation: Hailegnaw, N.S., L. Yuncong, and H.K. Bayabil. 2023. Impacts of seawater flooding on soil nutrient dynamics. Florida Section-American Society of Agricultural and Biological Engineers (FL-ASABE) Annual Meeting. Duck Key, FL. June 4 - 6, 2023. Oral presentation.
• Type: Conference Papers and Presentations Status: Published Year Published: 2023 Citation: Bayabil, H.K., N.S. Hilegaw, M. Berihun, Y. Li, and B. Gao. 2023. Impacts of flooding-induced salinity on soil hydrology and nutrient leaching. American Society of Agricultural and Biological Engineers (ASABE) Annual International Meeting. Omaha, NE. July 9 - 12, 2023. Poster presentation.
• Type: Conference Papers and Presentations Status: Published Year Published: 2023 Citation: Bayabil, H.K., Y. Li, and B. Gao. 2022. Risks of Saltwater Intrusion and Flooding on Agricultural Soils in South Florida. ASA, CSSA, SSSA International Annual Meeting. Baltimore, MD. Virtual. Nov 6-9, 2022. Oral presentation.

Progress 07/01/21 to 06/30/22

Outputs
Target Audience:The target audience for our research during the reporting period includes researchers, scientists, graduate students, extension agents, certified crop advisors, congressional staffers, and the general public at large. Changes/Problems:Installation of water quality groundwater monitoring wells in our study area requires getting a permit from Miami-Dade County's (where the project is located) Department of Environmental Resources Management (DERM). This process also takes time. On the other hand, DERM and South Florida Water Management District (SFWMD) collect groundwater and surface water quality parameters from several sites. These datasets are publicly available. As a result, a change of plan was requested and approved by the program director so that publicly available groundwater monitoring data will be used for the project. Labor shortage and increases in minimum wages. Our requested budget in the proposal for OPS personnel was $8.46/hr. However, with the current labor market and following Florida's recent efforts to increase the minimum wage to $15/hr., it is becoming very difficult to get a reliable person who can help the team with the project. What opportunities for training and professional development has the project provided?One graduate student is conducting his research on this project. In addition, three OPS personnel and one research technician are involved in the project and are being trained in several multidisciplinary concepts through one-to-one mentorship, discussions, and regular interactions with the project team. Graduate students and research technicians were trained to conduct literature reviews, writing factsheets, and data analysis. How have the results been disseminated to communities of interest?During this project reporting period, an extension factsheet was published. In addition, two members of the project team (Bayabil and Li) were invited by the Soil Science Society of America (SSSA) to give a congressionalbriefingon the threats of saltwater intrusion on South Florida's agriculture and environment. During thebriefing, the team had the opportunity to draw the attention of lawmakers and staffers to the issue, and theirbriefingcould potentially contribute to shaping policy towards saltwater intrusion and salinity mitigation and adaptation strategies in South Florida. Moreover, one news column entitled "What rising sea levels mean for agriculture in South Florida" and an opinion piece entitled "Rising seas: Florida farmers, vulnerable to salt, should seek sustainable methods" were published on the Tampa Bay Times and the Palm Beach Post, respectively. Three seminar presentations were also given to broader audiences. In addition, one workshop entitled "Saltwater Intrusion and Flooding: Risks on Soils, Plants and Environmental Health" in May 2022. Five speakers were invited to give presentation and 63 participants of the 75 registered attended the workshop. A conference abstract entitled "Risks of Saltwater Intrusion and Flooding on Agricultural Soils of South Florida" was submitted for the 2022 ASA, CSSA, SSSA International Annual Meeting and will be presented in November 2022. What do you plan to do during the next reporting period to accomplish the goals?Continue greenhouse column experiment using agricultural soils and seawater to evaluate the potentials of hydrogel, biochar, organic mulch, and gypsum in mitigating negative effects of salinity for the two agricultural soils. Continue analyzing soil samples for physical, chemical, and biological properties; and porewater samples for water quality. In addition, monitor greenhouse gas emissions from soils with different soil amendments. Collect time series soil moisture, temperature, and electrical conductivity data from column-based experiments. Collect and process long-term data from ground water monitoring wells from the South Florida Water Management District (SFWMD) and Department of Environmental Resources Management (DERM) of Miami-Dade County database on ground water level and water quality parameters needed for developing landscape-scale models to simulate risks of seawater intrusion and its effect on soil health indictor parameters of agricultural soils. Start developing a hydrologic model for simulating saltwater intrusion and potential impacts on agricultural soils. Publish one refereed manuscript and present project results at least at two conferences and/or professional meetings.

Impacts
What was accomplished under these goals? Column experiments were conducted in a greenhouse using Krome and Biscayne soils. Baseline experiments were conducted by flooding soils with sea and freshwater for 1, 7, 14, and 28 days. Soil moisture, electrical conductivity, and temperature readings were collected using sensors and a data logger throughout the experiment. In addition, pore water samples were collected from each experiment. Samples were analyzed for nutrients and other water quality parameters. Soil samples were tested for soil hydrological properties including moisture characteristic curves and hydraulic conductivity. Soil samples were collected and will be analyzed for microbial biomass. Greenhouse gas flux measurements were conducted for three gases including CO2, CH4, and N2O. Data will be analyzed to determine the multifaceted impacts of soil salinity on hydrology, soil health indicator parameters, greenhouse gas emission, and nutrient leaching from agricultural soils. A liquefied biomass hydrogel was produced has been optimized for soil application as an amendment for salt-affected soils. Liquefied biomass was prepared in a laboratory setup using sugarcane bagasse. Chemical inputs include ethylene carbonate anhydrous, ethylene glycol, sulfuric acid, and sugarcane bagasse. The sugarcane bagasse was solid, and the other materials were liquid, and a 1:5 solid-to-liquid mixing ratio was used. The hydrogel was tested under laboratory conditions and results showed that the hydrogel significantly reduced salt in porewater as well as in soil. In addition, one peer-reviewed manuscript entitled "Using liquefied biomass hydrogel to mitigate salinity in salt-affected soils" was submitted for publication to the journal Chemosphere. Several incubation experiemtns were conducted in a greenhouse using different biochar types. The experiments were intended to screen best biochar types that will beused as a soil amendment on salt-affected soils. The experiment is currently ongoing but preliminary results showed that biochar could be used as a soil amendment in salt-affected soils.

Publications

• Type: Other Status: Published Year Published: 2022 Citation: Bayabil, H.K., Y. Li, J. H. Crane, B. Schaffer, A.R. Smyth, S. Zhang, E.A. Evans, and T. Blare. 2022. Saltwater Intrusion and Flooding: Risks to South Floridas Agriculture and Potential Management Practices. University of Florida IFAS Extension #AE572. https://edis.ifas.ufl.edu/publication/AE572
• Type: Journal Articles Status: Under Review Year Published: 2022 Citation: Bewuket B. Tefera, Haimanote K. Bayabil, Zhaohui Tong, Fitsum T. Teshome, Yuncong C. Li, and Bin Gao. 2022. Using liquefied biomass hydrogel to mitigate salinity in salt-affected soils. Chemosphere. Under review

Progress 07/01/20 to 06/30/21

Outputs
Target Audience:The target audience for our research during the reporting period includes researchers, scientists, graduate students, extension agents, and the general public at large. Changes/Problems:The project started on June 1, 2020, during the COVID-19 pandemic. At the time, the Tropical Research and Education Center of the University of Florida, where the project is being conducted, was under lockdown. This delayed the project by several months. In addition, the start date for a Ph.D. student was delayed by one year. Sensor issues: 5TE sensors (METER Group, Inc. USA) were purchased for the project. These sensors measure temperature, electrical conductivity, and soil moisture. The sensors are calibrated to account for temperature and electrical conductivity levels in moisture readings. However, the sensors were only calibrated by the manufacturer for lower electrical conductivity levels not for conditions that involve seawater. As a result, custom calibration is needed for these sensors at higher electrical conductivity levels. However, the custom calibration can be done only up to 20 (dS/m) electricidal conductivity levels, and therefore, the custom calibration will solve the problem only partially. Labor shortage and increases in minimum wages. Our requested budget in the proposal for OPS personnel was $8.46/hr. However, with the current labor market and following Florida's recent efforts to increase the minimum wage to $15/hr., it is becoming very difficult to get a reliable person who can help the team with the project. What opportunities for training and professional development has the project provided?One graduatestudent is conducting his research on this project. In addition, two OPS personnel and one research technician are involved in the project and are being trained in several multidisciplinary concepts through one-to-one mentorship, discussions, and regular interactions with the project team. Graduate students and research technicians were trained to conduct literature reviews and writing draft manuscripts. How have the results been disseminated to communities of interest?During this project reporting period, a peer-reviewed manuscript was published. In addition, one conference presentation was given at the American Society of Agricultural and Biological Engineers (ASABE) annual meeting. What do you plan to do during the next reporting period to accomplish the goals?Continue greenhouse column experiment using agricultural soils and seawater to investigate the effects of soil salinity on soil physical, chemical, and biological properties, water quality based on pore water samples. In addition, monitor greenhouse gas emissions from soils. Collect time series soil moisture, temperature, and electrical conductivity data from column-based experiments. Organize and prepare long term data from ground water monitoring wells from the South Florida Water Management District (SFWMD) and Department of Environmental Resources Management (DERM) of Miami-Dade County database on ground water level and water quality parameters needed for developing landscape-scale models to simulate risks of seawater intrusion and its effect on soil health indictor parameters of agricultural soils.

Impacts
What was accomplished under these goals? Krome and Biscayne soils needed for the project were collected. Column experiments were set up in a greenhouse that flooding and leaching of soils with fresh and seawater were. Columns were constructed using six-inch diameter PVC pipes. The PVC columns were constructed with drain holes at the bottom to allow saturating and draining columns depending on the experiment. In each column, three soil moisture, temperature, and electrical conductivity sensors were also installed at three depths. In addition, pore water samplers (Rhizons) were installed at three depths of each column for pore water sampling for water quality analysis. PVC end caps were constructed and will be used as chambers during greenhouse gas sampling. In addition, greenhouse weather is being continuously monitored using a weather station. Currently, a series of greenhouse experiments are currently being conducted on Krome and Biscayne soils to investigate the multifaceted impacts of soil salinity on hydrology, soil health indicator parameters, greenhouse gas emission, and nutrient leaching from agricultural soils.

Publications

• Type: Journal Articles Status: Published Year Published: 2021 Citation: Bayabil, H.K., Y. Li, Z. Tong, and B. Gao. 2021. Potential management practices of saltwater intrusion impacts on soil health and water quality: a review. Journal of Water and Climate Change; 12 (5): 1327⿿1343. doi: https://doi.org/10.2166/wcc.2020.013
• Type: Conference Papers and Presentations Status: Other Year Published: 2020 Citation: Bayabil, H.K., J. Zhang, Y. Li, and F.T. Teshome. 2020. Effects of Organic Amendments on Evaporation Characteristics of Drying Soils. American Society of Agricultural and Biological Engineers (ASABE) Annual International Meeting. Virtual. Jul 13, 2020 - Jul 15, 2020.