A bioassay of crop response to fertilizer nutrients in soils from a chronosequence of reclaimed natural gas pipeline rights‐of‐way

Abstract

Construction of underground pipelines on cropland impacts the soil ecosystem, resulting in crop yield losses persisting for several years after right‐of‐way (ROW) reclamation. Information on whether higher than recommended fertilizer application rates could improve productivity of reclaimed ROWs is scarce. The objective of this growth room bioassay was to determine the productivity response of a chronosequence of reclaimed ROW soils to differential fertilizer rates. Bulk soil samples were collected from the 0 to 20 cm soil layer on two ROWs of different ages (i.e., time since reclamation, TSR). The experiment was laid out in a completely randomized design with a 3 × 3 factorial treatment structure with three replications per treatment. The factors were TSR (4 and 10 year plus undisturbed (off‐ROW) sites) and fertilizer application rates (no fertilizer (Check); recommended rate (100%) of nitrogen (N), phosphorus (P), potassium (K), and sulphur (S); and 150% of the recommended N, P, K, and S rates). The recommended nutrient rates produced 66% lower canola dry matter yield (DMY) and 45% lower wheat DMY in the 4‐year ROW soil relative to the off‐ROW soil. Increasing the rate to 150% of the recommended rate significantly increased canola and wheat DMY in the 4‐year ROW soil to levels similar to those in the off‐ROW soil receiving the recommended rate. Nitrogen uptake by canola and wheat was 30%–45% lower, while P uptake was 40%–55% lower in the ROW soils than in the off‐ROW soil. These results indicate incomplete recovery of the ROW soils within at least the first 4 year following completion of reclamation. However, crop yields were not significantly different between the 10 year ROW and the off‐ROW at 100% fertilizer rate suggesting that productivity had been restored to off‐ROW levels by year 10 following reclamation. Findings from this study will contribute towards the formulation of strategies for improving the productivity of reclaimed ROWs on cropland.