Soils in transition: saltwater intrusion alters soil chemistry in agricultural fields

As global sea-levels rise, low-lying coastal lands are subject to shallow coastal flooding and saltwater intrusion, affecting the productivity of farmlands worldwide. Soil biogeochemistry can be dramatically altered as saltwater intrudes agricultural fields. We selected three farm fields in Somerset...

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Bibliographic Details
Published in:Biogeochemistry 2019-02, Vol.142 (3), p.339-356
Main Authors: Tully, Katherine L., Weissman, Danielle, Wyner, W. Jesse, Miller, Jarrod, Jordan, Thomas
Format: Article
Language:English
Subjects:
Agricultural land
Agricultural management
Agricultural production
Agricultural resources
Agrochemicals
Biogeochemistry
Biogeosciences
Climate change
Coastal management
Coastal zone management
Crystal structure
Crystallinity
Earth and Environmental Science
Earth Sciences
Ecosystems
Electrical conductivity
Electrical resistivity
Environmental changes
Environmental Chemistry
Fertilizers
Fields
Flooding
Iron
Life Sciences
Organic chemistry
Organic soils
Organometallic complexes
ORIGINAL PAPERS
Phosphorus
Saline water
Saline water intrusion
Salt water intrusion
Saltwater intrusion
Sea level
Sea level changes
Soil
Soil chemistry
Soil types
Sulfates
Tributaries
Water quality
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Summary:As global sea-levels rise, low-lying coastal lands are subject to shallow coastal flooding and saltwater intrusion, affecting the productivity of farmlands worldwide. Soil biogeochemistry can be dramatically altered as saltwater intrudes agricultural fields. We selected three farm fields in Somerset Co., Maryland affected by saltwater intrusion and established transects from the ditch bank to the center of the cropped field and collected soils (to ~ 140 cm) at five points along this transect. The three fields in this study have different soil types, are located along different tributaries in the county, and receive different fertilizer rates, yet they all showed similar biogeochemical responses to saltwater intrusion. We found an increase in electrical conductivity and concentrations of chloride, sulfate, and forms of phosphorus (P) from the center of the field (low) to the ditch banks (high). As inundation increased, the structure of iron (Fe) changed from crystalline to non-crystalline forms, possibly due to dissolution under saturated conditions. Near the edges of the fields, the formation of organometallic complexes was positively associated with increases in soil carbon and organic soil P concentrations. Compared to areas of the fields where crops were actively growing, soil P concentrations are 2–3 higher on field edges, suggesting that saltwater intrusion may be transporting P to the edges of agricultural fields. These field edges are frequently saturated, thus reduction of Fe could lead to P release into solution potentially harming water quality. As climate change pushes saltwater further inland, it is important to understand the biogeochemical consequences for ecosystems up- and downstream. Understanding the how fractions of P move and change across fields affected by saltwater intrusion will be crucial for planning current and future management of coastal agricultural lands.
ISSN:0168-2563
1573-515X
DOI:10.1007/s10533-019-00538-9