Effects of deep ripping and organic matter amendments on Ap horizons of soil reconstructed after coal strip-mining

Deep ripping is a common management technique used to shatter dense subsurface soil horizons that limit percolation of water and penetration of roots. Most studies have concentrated on the effects of deep ripping on subsoils, with few examining the effects on surface soil horizons. A study was conducted on reclaimed fields (undisturbed soil Albic Luvisol) at the Highvale coal mine approximately 80 km west of Edmonton, Alberta, Canada, with objectives to evaluate the effect of deep ripping, with and without the use of organic matter amendments, on the physical and chemical properties of Ap horizons of reconstructed minesoils. Significant treatment effects were identified for particle size distribution (alt fractions), plasticity index and the October mean penetration resistance (PR), but effects on bulk density, soil water content at the time of sampling, water retention characteristics and modulus of rupture were non-significant. Soil chemical properties significantly affected included pH, soluble Ca and Mg, exchangeable Na and K, exchangeable Ca:Na ratio and loss of ignition. Addition of subsoil to the Ap horizon as a result of deep ripping likely caused the changes. They are expected to make the seedbed more difficult to cultivate and manage unless specific management practices such as organic matter additions are adopted to overcome the detrimental changes in soil properties that have occurred.