Four decades of continuously applied tillage or no‐tillage on soil properties and soil morphology

Abstract

Abstract As increasing amounts of cropland are managed using no‐tillage (NT), information is needed to assess long‐term impacts of this practice on soil profile properties. A well‐drained Wooster fine‐loamy (mixed, active, mesic, Oxyaquic Fragiudalf) soil and a poorly drained, Hoytville silty clay loam (fine, illitic, mesic Mollic Epiaqualf) were sampled. For comparison, adjacent undisturbed forested and grassed areas were sampled. Bulk samples were characterized using physicochemical, mineralogical, and micromorphological methods. At both sites stronger structure and more bioturbation was evident in the topsoil of NT than in PT leading to lower bulk density values and increased, highly connective macroporosity. Evidence for the formation of incipient E horizons was noted in the lower A horizons of soil in the NT plots. The cation exchange capacity (CEC) was increased at both sites with NT and is associated with the increase in soil organic C. The C/N ratio of the NT pedon was closer to that of the A horizon of the forest pedon than to that of the PT pedon. Comparisons of C levels with those estimated in the same soils prior to establishment of the grassed areas or tillage plots suggest that at the Wooster site the grass, NT, and PT pedons all sequestered C. Only the grass pedon sequestered C at the Hoytville site. For both sites, and especially for the well‐drained Wooster silt loam soil, continuous, long‐term NT management can sustain or even enhance soil functions as compared with long‐term PT management.