Saltwater Intrusion is So-dium Awful
Katie organizes sorghum samples in the lab.
Water is essential to life, especially for plants when it comes to agriculture. What happens when salts infiltrate the soil through the water, thus changing the biogeochemical cycling that maintains plant and soil health? This is the main consequence of saltwater intrusion, one of the many effects of sea level rise. As sea levels rise, the saltwater from nearby saline water bodies flows into agricultural fields, through freshwater aquifers and shallow groundwater tables [1]. When this occurs, agricultural fields are devastated due to the influx in sodium levels in the soil, which can cause serious damage to the soil over time [2]. This effect is called sodium toxicity that can lead to soil dispersion. Dispersion can leave soils more saturated with water, causing issues with root penetration. Because of this, plants struggle to survive and crop yields significantly decline. This forces farmers to consider what they should do with their land, as they are often faced with the decision to either continue farming (until they cannot) or abandon their land.
At the University of Maryland, the Tully Lab studies soil health and saltwater intrusion on coastal agricultural fields and the effects these occurrences have on farmers. While at the lab, my lab supervisor, Alison, and I have been focusing on the nutrient uptake of plant species in an adaptive farming approach. The particular plants we are studying include sorghum and soybean (which is a salt-tolerant crop). To test this, Alison and I have been performing a modified Kjeldahl digestion [3] on grain and leaf tissue samples of each plant. Samples are taken from participating farm sites on the Eastern Shore of Maryland. Digestions break the bonds within the grain or leaf tissue by boiling the reaction between sulfuric/salicylic acid and hydrogen peroxide [3]. We are then left with a liquid sample that can be analyzed on an Atomic Absorption Spectrometer (AAS) to determine their individual nutrient concentrations. In running these digestions of plant tissues along with their respective soils on an AAS, we are able to calculate the concentration of sodium in both the plant and the soil, thus giving us an idea about how much salt the plant may uptake from the soil. If farmers are presented with this data, they may consider this management strategy to increase land productivity and promote soil health.
References
Tully, K., Gedan, K., Epanchin-Niell, R., Strong, A., Bernhardt, E. S., BenDor, T., ... & Weston, N. B. (2019). The invisible flood: The chemistry, ecology, and social implications of coastal saltwater intrusion. BioScience, 69(5), 368-378.
Barlow, P. M., & Reichard, E. G. (2010). Saltwater intrusion in coastal regions of North America. Hydrogeology Journal, 18(1), 247-260.
Bradstreet, R. B. (1954). Kjeldahl method for organic nitrogen. Analytical Chemistry, 26(1), 185-187.