Crop production on heavily disturbed soils following crude oil remediation

Authors: CROAT, SAMANTHA - North Dakota State University; O'Brien, Peter; GASCH, CALEY - North Dakota State University; CASEY, FRANCIS - North Dakota State University; DESUTTER, THOMAS - North Dakota State University

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/17/2019
Publication Date: 2/26/2020
Publication URL: https://handle.nal.usda.gov/10113/6937388
Citation: Croat, S.J., O'Brien, P.L., Gasch, C.K., Casey, F.X., Desutter, T.M. 2020. Crop production on heavily disturbed soils following crude oil remediation. Agronomy Journal. 112:130-138. https://doi.org/10.1002/agj2.20077.
DOI: https://doi.org/10.1002/agj2.20077

Interpretive Summary: Crude oil spills on agricultural land decrease crop yields, so many resources are often devoted to removing the oil from soil (i.e., remediation). However, many strategies that are used to remediate the soil can also harm soil characteristics, requiring additional resources and management techniques to improve soil production potential. This research describes how two remediation strategies, modified land-farming and ex-situ thermal desorption, used after a crude oil spill in North Dakota, USA affect the ability of the soil to produce two regionally important crops, spring wheat (Triticum aestivum L.) and field pea (Pisum sativum L.). The modified land-farming technique was conducted by excavating the contaminated soil and continuously tilling it, which removed the oil by volatilization and degradation by microorganisms. The ex-situ thermal desorption was conducted by heating contaminated soil up to 400 °C to ‘burn off’ the oil (i.e., via enhanced volatilization, combustion, and/or pyrolysis). Crops were grown on remediated soils for three years, and yields were 61 ± 20% lower in the modified land-farm soils and 52 ± 25% lower in thermal desorption-treated soils when compared to crops grown in non-contaminated topsoil. However, when those soils were mixed with native topsoil, crop yields improved, likely due to increased soil organic matter and biological activity. Thus, soil mixing may be a promising technique to improve crop yield and quality after soil remediation. These findings will be relevant to land managers, the oil and gas industry, and government regulators when making decisions following crude oil spills. Overall, these findings reinforce that crop production is linked with soil properties, so long-term success requires a holistic approach to soil management.

Technical Abstract: Cropland contaminated by crude oil typically requires remediation before it can meet pre-contaminated productivity potentials. Remediation strategies focus on removing the contaminant, but they also often alter soil properties, which affects the capacity of the land to sustain agricultural production. This research describes crop production following the remediation of crude oil contaminated soil in North Dakota, USA using two different strategies, a modified land-farming technique and ex-situ thermal desorption. Wheat (Triticum aestivum L.) and field pea (Pisum sativum L.) were grown in soils treated by both of those techniques, as well as mixtures of each treated soil with native topsoil. Across three growing seasons of comparisons to native topsoil, crop production was 61 ± 20% lower in the modified land-farm soils and 52 ± 25% lower in thermal desorption-treated soils; these yield declines were likely associated with reduced soil organic carbon levels. Notably, the soil mixtures had higher soil organic carbon levels and matched the native topsoil in both yield and protein content, suggesting that soil mixing may be a promising tool in cropland soil reclamation. Overall, these findings reinforce that crop production on reclaimed land is linked with soil properties, so long-term reclamation success requires a holistic approach to soil management.