RESIDUAL EFFECTS OF COMPACTION AND TILLAGE ON THE SOIL PROFILE CHARACTERISTICS OF A CLAY-TEXTURED SOIL

Abstract

Detailed soil profile descriptions were made to assess the residual effect of compaction and tillage treatments applied 10 yr ago on a Ste-Rosalie clay. The treatments applied consisted of five passes at a contact pressure of 61.8 kPa with no tillage, 15 passes of 61.8 kPa with chiselling, moldboard plowing, no tillage, subsoiling, and a control. The results were analyzed using nonparametric statistics. The untilled plots that received 15 wheel passes showed mottling that was more abundant and closer to the surface than the other plots while the subsoiled plots had a finer, less abundant and deeper mottling than the other plots. Peds in the Ae horizon were finer in the subsoiled and chiselled plots and coarser in the untilled plots and conventionally tilled plots that received 15 vehicle passes. It appears from this work that the effect of compaction is very persistent in clay soil and that subsoiling followed by reduced traffic can have a long-term effect on soil structure. Key words: Compaction, tillage, profile descriptions, clay soil