Today marks the end of my time as an intern in the Agroecology Lab. I have been fortunate enough to spend the entirety of my senior year working in the lab with Dani Weissman and the other graduate students, Cullen McAskill the wonderful lab technician, and my fellow interns. Through my various research experiences in the lab, I have learned so much about biogeochemical cycling processes that impact agriculture, the importance of agroecology to integrate ecological and social approaches to agriculture, and standard chemical analysis research practices.
This semester I focused my efforts on a long-term research study to understand different nutrients, like nitrogen and phosphorus, that are dissolved and bound to soil particles in water samples taken from various agricultural plots on the Eastern Shore. Nitrogen in this form is formally called “Dissolved Organic Nitrogen” (DON), while other forms of nitrogen often found in the soil include nitrate and nitrite, which are necessary for plant growth. The agroecology lab is investigating these different forms of nutrients because it is important to understand how changing environmental conditions may impact the future of agriculture. Rising sea levels, for example, is causing saltwater from the ocean to intrude into agricultural plots on the Eastern Shore. This alters the chemical and biological processes that take place in agricultural soils (Osburn, 2016; Weston, 2006). To understand how nutrient forms have been changing over time in response to saltwater intrusion, I conducted digestion experiments on water samples to specifically target dissolved organic nutrients. Essentially, the experiment required me to add various chemicals to the water samples (as shown in Figure 1) and then run them through an autoclave, which heats the samples up to extremely high temperatures. This breaks up any bonds between the nutrients and dissolved soil components to isolate the nutrients to be further analyzed.
The results of this experimental digestion process will provide important information on plant nutrient availability once they undergo a next step of further chemical analysis. It is a good feeling to be able to contribute to the research findings of the Agroecology Lab. I will sorely miss my time working there now that the semester has come to a close, but I will be forever grateful to all that I have learned and for how it has changed my perspectives of agroecology.
Osburn, Christopher L., Lauren T. Handsel, Benjamin L. Peierls, and Hans W. Paerl. 2016. “Predicting Sources of Dissolved Organic Nitrogen to an Estuary from an Agro-Urban Coastal Watershed.” Environmental Science & Technology, 50: 8473-8484.
Weston, Nathanial B., Ray E. Dixon, and Samantha B. Joyce. 2006. “Ramifications of increased salinity in tidal freshwater sediments: geochemistry and microbial pathways of organic matter mineralization. Journal of Geophysical Research, 111: G01009.
- By Alexis Boytim
I am Jonathan Moy, an undergraduate intern in the Agroecology lab. I work with Elizabeth de la Reguera, an MS student here, in two of her projects. Her work is largely on how saltwater intrusion in Maryland affects the carbon found in soil. We recently finished transferring four thousand switchgrass plants to UMD’s greenhouse. Later in the year, the lab will be planting the switchgrass along with other salt-tolerant plants in saltwater intruded agricultural plots to determine the carbon the plants imparted in the soil. The data from that experiment will be helpful in giving farmers in Maryland a well-supported reason to use salt-tolerant crops in their crop rotations. The project I am working on right now examines the aggregate distribution in saltwater intruded agricultural fields. Soil aggregates are important to the available nutrients to the soils . We are most closely looking at soil carbon—thus the title of this post. Carbonation the way most people use it usually refers to carbon dioxide reacting with a beverage to make it effervescent. While that doesn’t happen in our soils, carbon is still very interesting in soils! The method we are using uses a series of sieves to separate the soil carbon by availability [2,3]. Essentially, the smaller the aggregates are, the less available the carbon is to the plants’ roots . One of the pictures with this post shows Elizabeth displaying the second smallest sieve we use in this experiment. Fun fact: the picture also features the very first sample we processed for this experiment.
During spring break, I was given the opportunity to visit the sites that we are working on! You may not be able to tell from the picture (I’m the guy in blue), but I had a blast soil sampling. If you look really closely, you can see that I’m smiling. Those soils were the same soils that we are processing right now, so that is just one more thing to be excited about when processing my samples. Before that, I spent a lot of time in the Greenhouse seeding, thinning, and transferring switchgrass until we had four thousand switchgrass plants individually growing in deep planting plugs.
- By Jonathan Moy
Ontl, T.A. et al. (2013). Topographic and Soil Influences on Root Productivity of Three Bioenergy Cropping Systems. The New Phytologist, 199, 727-737. doi: 10.1111/nph.12302
Elliott, E.T. (1986). Aggregate Structure and Carbon, Nitrogen, and Phosphorus in Native and Cultivated Soils. Soil Science Society of America Journal. 50, 627-633.
Six, J. et al. (2000). Soil Structure and Organic Matter: I. Distribution of Aggregate-Size Classes and Aggregate-Associated Carbon. Soil Science Society of America. 64, 681-689.