Saltwater – it belongs in the ocean, right? Well, sort of. Saltwater can move inland through flooding during high tides or through the shallow groundwater table. This phenomenon is known as saltwater intrusion, is increasing in frequency as sea levels rise. This can cause big issues in areas like Maryland’s Eastern Shore communities, where farms line the coasts. These farms grow crops which can only handle so much salt, but as more saltwater silently creeps into these fields, these crop’s tolerances are exceeded, killing them. This salt-death can be caused by the drying out of plant roots (Ardón et al, 2017). In the Agroecology lab we want to tackle the issues saltwater intrusion causes on these coastal farms. Cover crops are crops planted during the off-season that cycle nutrients found in the soil, preventing them from leaching away through rainwater. Cover crops can be used to lessen the amount of nutrients that escape these agricultural systems, combating the impacts saltwater intrusion may have on coastal farms (Gómez et al, 2009). Through the proper planting of select cover crops, farms in places like the Eastern Shore may stay in business longer, but it’s going to take some research to figure out the secret formula.
Observing cover crop impact requires lab work. For me, this means working in two places, the greenhouse and the Plant Sciences building. While at the greenhouse, I sort and filter porewater samples. Porewater is water that is found between the small spaces between soil particles, which have been collected from farm soils on the Lower Eastern Shore of Maryland that may be influenced by saltwater intrusion. At the Plant Sciences building, Dani Weissman and Natalie Ceresnak run filtered samples on a colorimeter to detect nitrogen and phosphorus levels, while another sample is used to measure pH, salinity, and conductivity. Soil chemistry plays a direct role in the development of planted crops, and by studying the chemical content of these samples we can find how to properly mitigate the impacts of saltwater intrusion.
Ardón, M., Helton, A. M., Scheuerell, M. D., & Bernhardt, E. S. (2017). Fertilizer legacies meet saltwater incursion: Challenges and constraints for coastal plain wetland restoration. Elementa, 5(0), 41. doi:10.1525/elementa.236
Gómez, J. A., Guzmán, M., Giráldez, J. V., & Fereres, E. (2009). The influence of cover crops and tillage on water and sediment yield, and on nutrient, and organic matter losses in an olive orchard on a sandy loam soil. Soil and Tillage Research,106(1), 137-144. doi:10.1016/j.still.2009.04.008
- By Ethan Glaudemans
If you have been in the lab over the past month when I’ve been working with Dani Weissman’s water samples from various agricultural plots along the Eastern Shore, you most likely walked into the awful smell of rotten eggs. This smell comes from bacteria that thrive in low oxygen environments and feed on small amounts of sulfur that is present within the water in places such as agricultural ditches. Although these samples are not necessarily pleasant to work with, they are important when considering the long-term project that Dani has been working on since 2016. We are analyzing these samples to examine the levels of nitrogen (N) and phosphorus (P) loading in the Chesapeake Bay estuary in response to saltwater intrusion. These studies of coastal agricultural communities are extremely important as they are the leading edge of climate change. The intrusion of saltwater from rising sea levels and coastal flooding can cause an unpredictable source of nutrients (N & P) to waterways along the Eastern Shore. Past applications of N and P on farms are remobilized by the intruding waters, which is the main source of the nutrients. The lab work that I am helping Dani with this semester, coupled with the past two years of data, will be used to help illustrate the effect of saltwater intrusion on our coastlines.
My experience in the lab so far this semester has been very informative and interesting. I have learned many things up to this point and anticipate learning many more. At the beginning of the semester, I measured out samples for dissolved organic phosphate, which Dani then ran on the flow-injection colorimeter. I’ve also learned how to run a standard curve and have had a chance to help run the atomic absorption spectrometer. As of late, I have been analyzing water samples for electrical conductivity and pH and preparing more samples for P measurements. This has all been valuable information that I will use in the future. As it is still rather early in the semester, there is plenty of time and opportunity to learn new things and to continue helping Dani with her project!
- By Kenny Polk
Ardón, M., A. M. Helton, M. D. Scheuerell, and E. S. Bernhardt. 2017. Fertilizer legacies meet saltwater incursion: challenges and constraints for coastal plain wetland restoration. Elementa Science of the Anthropocene 5: 41.
Hartzell, J. L., and T. E. Jordan. 2010. Shifts in the relative availability of phosphorus and nitrogen along estuarine salinity gradients. Biogeochemistry 107:489–500.
The AgroEcoLab is seeking a PhD student to work on our saltwater intrusion project! See all details and how to apply here.
Recent research in the agroecology lab shows that cover crop reduce nitrate leaching by as much as 56% compared to farms without cover crops. Check out the new article here!
My intern experiences this summer were nothing short of great. This summer, I helped Anna Kottkamp with her study of Delmarva Peninsula’s geographically isolated wetlands or Delmarva Bays. These wetlands are surrounded by upland and have no apparent surface water connectivity (Tiner 2003). Despite their geographic isolation, Delmarva Bays offer many ecosystem services such as providing habitat to many rare and endangered species (Sharitz and Gibbons 1982) and enhance local water quality (Phillips et al 1993).
With the lab and field work required to study these wetlands, I learned valuable skills that I can apply in my future career. One of these lessons is field preparedness. Whether your work is in the woods or in agricultural fields, or whether you are soil sampling or water sampling, fieldwork is an essential part of research and it comes with physical and environmental hazards. This guide is intended to share some things that I did right and some lessons I learned the hard way when it comes to field preparedness.
Phillips PJ, Denver JM, Shedlock RJ, Hamilton PA (1993) Effect of forested wetlands on nitrate concentrations in ground water and surface water on the Delmarva Peninsula. Wetlands Wetlands 13: 75-83.
Sharitz RR, Gibbons JW (1982) The ecology of southeastern shrub bogs (pocosins) and Carolina Bays: a community profile. FWS/OBS-82/04. US Fish and Wildlife Service, Division of Biological Services, Washington, DC
Tiner, R. (2003). Estimated extent of geographically isolated wetlands in selected areas of the united states. Wetlands, 23(3), 636-652.
-By Bianca Noveno
Salt-water intrusion (SWI) is a new challenge for farmers on the Eastern Shore. As sea levels continue to rise, more and more farm fields are becoming increasingly “salty,” often resulting in reduced and even complete loss of productivity. To make matters worse, there is evidence that salt accumulation also increases phosphorus loads to downstream waters. In the case of the Chesapeake Bay, this could reverse recent restoration efforts and hard fought water quality improvements.
Kate Tully, Keryn Gedan, and others are studying this problem; and their work aims to provide solutions that both help farmers and mitigate potential water quality degradation. Read more about their work in recent articles in NPR and The Atlantic.
This week, I helped Kate and Keryn install new groundwater wells at several of their sites. I had a great time and definitely learned a lot about agriculture on the Eastern Shore and salt-water intrusion. Below are a few pictures!
- By Nate Jones (postdoc at SESYNC)
At the AgroEcology lab, I primarily work with Josh Gaimaro on his research pertaining to cover crop use as a best management practice. Within my first two weeks of working in the lab, I was introduced to potassium chloride (KCl) extractions, which are one of the central procedures to his project. KCl extractions allow us to quantify the nitrogen concentration in soils, which helps model how the nitrogen moves through the soil, and how much of it gets taken up by plants or leached. Over the past two years, Josh collected over 1,000 samples, all which needed to be organized, weighed out, and extracted. Additionally, each sample required a replicate for quality control, which doubled the extraction count. When I was first introduced to the procedure, I did not understand the sheer quantity of samples I would need to process...
The first KCl extraction wasn’t perfect, even though Josh made the entire process look quick and effortless at first glance. The procedure is as follows: After weighing out a set of soil samples, we calibrated a pipette to dispense KCl into each tube. Afterwards, these samples are transferred to a shaker table, where they shake for an hour. In the meantime, you must prepare for the extraction which consists of setting up scintillation vials, placing funnels into them, and folding filter paper for each sample. Next, the tubes must go on a centrifuge to speed up filtering. However, we could only centrifuge 12 samples at a time, so it would take some time to get through all the samples. After the centrifuge, the samples are all filtered and organized once again.
The first extraction was around 75 samples, which wasn’t too intense since I was shadowing Josh and he was leading the procedure. Everything ran smoothly until the very end, where we were pouring the samples into the vials. We were using a shaky wooden device, which held the funnels a little above the vials, but didn’t secure the vials from moving. As I was pouring a sample, I accidentally knocked one over and it caused a domino effect! Three samples went down, and I was utterly embarrassed. Josh assured me that it is no big deal, and that we will redo these samples another day. Little did I know, I would do an extraction just like this at least twice a week at the minimum throughout the entire summer. The following day I was asked if I could do an extraction by myself with the help of another intern. Without giving it much thought, I replied “sure”, and began my journey of KCl extractions.
Once I got into the groove of things and familiarized myself with the procedure, I was averaging at 300 KCl extractions per day. This included the entire process- starting with weighing all the samples to cleaning up all of the dirty funnels and tubes. Little by little, I started working through these samples until the number of extractions left to do was zero. At first, the process didn’t seem to have an end, but somehow after three months of work, we finally finished the samples. Our last extraction was last Thursday, and was definitely bittersweet.
- By Christina Bychkov
Jones, D.L, Willett, VB. (2006) Experimental evaluation of methods to quantify dissolved organic nitrogen (DON) and dissolved organic carbon (DOC) in soil. Soil Biology and Biochemistry, 38:5: 991-999 https://doi.org/10.1016/j.soilbio.2005.08.012.
Murphy, D., Macdonald, A., Stockdale, E. et al. (2000) Biol Fertil Soils 30: 374. https://doi.org/10.1007/s003740050018
At 5:00 am on a Wednesday morning the sun has yet to rise in the Pocomoke River State Forest, but our team is already up cooking breakfast and putting on our boots to prepare for a day of work in the field. It’s important for us to get an early start in an attempt to beat some of the Maryland summer heat, or to make up for lost hours due to yesterday’s afternoon thunderstorm. We load up our truck with tape measures, augers, fertilizer, and of course our plants, switchgrass (Panicum virgatum) and saltmeadow corgdrass (Spartina patens). The purpose of this field excursion is to plant several salt tolerant crop species in order to see how they fare in the increasingly inundated and brackish farm fields of the eastern shore of Maryland, one of the regions most vulnerable to the effects of sea level rise in the entire country.
This summer I have been lucky enough to join the AgroEco Lab’s saltwater intrusion team and come along on multiple field excursions, where I have gotten to experience field work first hand and get a sense of what a typical day in the field looks like. Some may assume that scientists are only there to observe, and simply stand by making tick marks on their clipboards while others do the dirty work...but this couldn’t be further from the truth! One important thing I have learned this summer is that agroecologists are not afraid to get their hands dirty, and field work involves a great deal of manual labor, such a making soil “slushies” in order to install lysimeters, hammering probes 60 cm into the ground to get soil samples, and crawling up and down plots to plant our treatments.
During this planting excursion in particular I was thrown into the reality of field work: that it’s really hard! It involves long hours (sometimes dawn to dusk!), exposure to all kinds of weather, including sweltering heat and torrential downpours, strenuous labor, and worst of all, ticks! While some may know the eastern shore of Maryland for its picturesque landscapes of tall grasses blowing in the breeze against the backdrop of the Chesapeake Bay, or perhaps its delicious crab dinners, our field trips are certainly no vacation!
But sometimes these field excursions don’t seem like work at all, and the lines between work and leisure are more blurred. For instance, when I’m standing out on a wooden dock overlooking the bay, and behind me is a small cottage and willow tree that belong to a historic property, just down a dirt road from one of our field sites. Or when I get back from a long day in the field only to enjoy a lively make-your-own taco night with the rest of team, an evening fueled with laughter, stories, and an appreciation for good food. For all the things that make field work hard, there are plenty more that make it an incredible experience overall. As agroecologists we are lucky enough to get to go to so many extraordinary places and spend time outdoors, as well as get to bond with our fellow researchers, as a part of our job, which is a luxury not everyone has. I cannot wait to see all the places agroecology research will take me in the future!
- By Louisa Kimmell
Anderson, Eric K., et al. “Determining Effects of Sodicity and Salinity on Switchgrass and Prairie Cordgrass Germination and Plant Growth.” Industrial Crops and Products, vol. 64, Feb. 2015, pp. 79–87., doi:10.1016/j.indcrop.2014.11.016.
Titus, JG, and C Richman. “Maps of Lands Vulnerable to Sea Level Rise: Modeled Elevations along the US Atlantic and Gulf Coasts.” Climate Research, vol. 18, 2 Nov. 2001, pp. 205–228., doi:10.3354/cr018205.
If you have been around me in the lab for the last month, you might have caught me a few times watching a soccer game while scraping away soil samples. When there is a huge bin full of samples to scrape, you need something to pass the time. As a huge soccer fan, the World Cup brings me excitement every four years when it rolls around. Some of the countries I closely followed in this World Cup have players with great individual skill but have mostly gotten their nation to advance solely on team chemistry. So far, this observation has paralleled my experience in the Agroecology lab this summer.
I am working individually most days on Elizabeth de la Reguera’s project about how saltwater intrusion affects the storage of carbon in soil on agricultural fields. In this project, different soil aggregates are separated by sieving them from large to small particle size, until eventually silt and clay is left in the end. After the aggregates are dried in an oven, I weigh them and take them back to scrape in coin envelopes (shown in the picture). The amount of carbon is then tested after the samples are in envelopes. This work is important in observing how outside forces like saltwater intrusion can greatly affect aggregate stability . This research will hopefully help farmers take saltwater intrusion into account and seek solutions, such as establishing barriers to mitigate intrusion rate or adjusting crops to salt-tolerant species .
With the many individual projects the lab has, our “team chemistry” is still displayed. On a small scale, Elizabeth and I communicate well to ensure that her project is running smoothly. This can include relaying turkey tins to her car from the drying oven, needing more samples in the lab, or teaching me something new. In the field a couple weeks ago, I was part of a team of six when it came to installing lysimeters and soil sampling. We knocked out two fields in one day and got to go home a day early! On a large scale, the goal of our lab is to make agriculture more sustainable through research. We all know we aren’t making as much money as Messi or Ronaldo, but together we are definitely making an impact in the environmental and agricultural world. Even with the World Cup coming to an end soon, I still have a lot of great experiences left in the lab this summer.
-By Drew Mandich
USDA Natural Resources Conservation Service. (1996). Soil Quality Indicators: Aggregate
Stability. Retrieved from
Duan, Y. (2016). Saltwater intrusion and agriculture: a comparative study between the
Netherlands and China. TRITA-LWR Degree Project 2016:20.
We are interested in varying osmotic potentials because we want to know if crop death seen on saltwater intruded farm fields is due to the inability of plants to pull water out of the soil matrix or because of salt toxicity. This work will be complemented by another experiment of seed germination at varying sodium chloride (NaCl) concentrations in order to tease apart whether seeds are experiencing osmotic stress or ionic/salt stress.
This first year has been a year of logistics! Between field work on the lower eastern shore, to aggregate fractionation at the University of Maryland College Park, to seed germination experiments and George Washington University, I feel like the ring leader of a scientific circus. The second year can only be crazier and more exciting with all the data to analyze and a story to tell!
- By Elizabeth de la Reguera
Six, J., K. Paustian, E.T. Elliott, C. Combrink. 2000. Soil Structure and Organic Matter: I. Distribution of Aggregate-Size Classes and Aggregate-Associated Carbon. Soil Science Society of America Journal. 64:681-689.
Weil, R.R. and N.C. Brady. 2016. The Nature and Properties of Soils. 15th ed. Pearson Education, Columbus. ISBN: 9780133254488