Soil property distribution following oil well access road removal in North Dakota, USA

Abstract

Increases in oil extraction on public lands in the US northern Great Plains has created an extensive network of access roads that must be removed upon well abandonment. However, the effects of road removal on soil properties are largely unknown. The objective of this study was to determine whether soil properties were altered on removed roadbeds and whether time since road removal has improved soil properties. Soils were sampled (n = 208) on perpendicular transects across removed roadbeds and extending into undisturbed areas on 16 restored roads located on two ecological site classifications such as (i) thin loamy and (ii) sandy. A Bayesian hierarchical mixed model was used to determine posterior predictive distributions and means of measured particle size distribution, gravel content, infiltration rate, pH, electrical conductivity, sodium adsorption ratio, CaCO3 content, and organic matter. Alterations in the predicted distribution of particle size, pH, CaCO3 content, and sodium adsorption ratio were attributed to mixing topsoil with subsoil during the road removal process. Soil organic matter decreased on roads. Most importantly, measured soil properties on removed roads did not improve with time since road removal. The alterations in soil properties can have lasting effects on nutrient availability, vegetation dynamics, and ecological resiliency of the native prairie.