Consequences of gas pipeline hauling on changes in soil properties over 3 years

Abstract

The manifold requirements of arable soils e.g. as construction sites for gas pipes or electricity cable hauling can result in extensive stress and deformation processes. It is therefore hypothesized, that external impacts as the load applications by the used construction machinery, the excavation and following refilling activities cause a loss of important soil functions and changes in soil strength. The recovery of soil functions requires efficient amelioration methods in order to re-achieve the site-specific crop yield potential.In course of the gas pipe installation in Eutric Cambisols in the Weichselian glacial till region of Mecklenburg West Pommerania (North Eastern Germany), undisturbed soil samples were taken below the plowed A-horizon in 50 and 80 cm depth in the traffic lanes and refilled pipeline trenches in the construction area as well as in the adjacent arable soils (which were used as references) directly and 3 years after the construction process.Analyses of soil porosity characteristics, air and saturated hydraulic conductivity as well as of soil strength (precompression stress value) indicate a severe loss of soil functions (especially air capacity and hydraulic conductivity) directly after the construction process (refilling of the material) compared to the reference soil. A harmful soil degradation could be verified down to 80 cm depth in the traffic lanes as a consequence of much too heavy machines used for the transportation and hauling of the pipes. After the refilling and leveling process together with the amelioration measures like the application of in total 5 Mg CaO ha−1 and the following cultivation of alfalfa seeded at the surface after the refilling and leveling, the air capacity and air conductivity was improved, but the precompression stress and the saturated hydraulic conductivity only slightly increased during the following 3 years. We conclude that such intense impacts require a longer time period to regain more rigid soil functions in spite of all the supportive amelioration approaches.