effects of tillage practices on soil penetration resistance, technical parameters and wheat yield

this study was carried out to evaluate the effects of tillage practices (with different depths) on soil penetration resistance, technical parameters and grain yield of wheat crop. the experiment was conducted as a randomized complete block design with three replications for two years. treatments included: moldboard plow fallowed by two passes of disc harrow and leveler (ct), two passes of disc harrow plus leveler (rt), subsoiler fallowed by two passes of disc harrow and leveler (s1d) and subsoiler fallowed by rotivator (s1r). the results showed that soil compaction and penetration resistance increased at the end of growth stages because of irrigation operations and cohesion force of soil particles. however due to increasing of cumulative infiltration, it can be concluded that subsoiler caused the formation of micro cracks in different depths of soil. from technical indices viewpoint comparing to ct treatment, s1d and s1r treatments saved fuel consumption up to 2.2 and 10.44 lit ha 1 and tillage operation time up to 0.58 and 1.54 h ha-1, respectively. the result of grain yield assessment showed an increase of 8.5% in grain yield after replacing moldboard plow with annual subsoiling. subsoiling has advantages such as, good technical indices, elimination of preplanting irrigation and fewer operations in planting time. finally, subsoiling increased grain yield by 22% as compared to reduced tillage practice