Effect of Tillage Systems on Compaction Characteristics of a Silty Clay Loam Soil

Soil compaction is one of the effective factors in reducing soil physical quality, which due to tillage operations can affect the relationship between water, soil and crop yield. The aim of this study was to investigate the effect of some tillage treatments on the compaction behavior of a silty clay loam soil. Core sampling was carried out during three years of tillage after barley harvest. The experiments were conducted as a randomized complete block design with three treatments i.e. conventional tillage, reduced tillage and no-tillage in 6 replications. Soil compaction characteristics including pre-compression stress, compression index and swelling index were determined based on confined compression test )CCT) at 100 hPa matric suction. The results showed that the tillage treatment had a significant effect on pre- compression stress, bulk density and soil moisture at the confidence level of% 5. The lowest amount of pre-compression stress with a value of 19.95kPa is related to conventional tillage treatments and the highest value with a value of 31.62 kPa is related to non-tillage treatment. The compression index was showed the highest value in conventional tillage compared to other treatments. The results of cyclic loading-unloading at a constant stress level (i.e. 50% of pre-compression stress) showed that the studied soil was less sensitive to repeated loading for no-tillage than reduced and conventional tillage treatments which can be attributed to weaker structure for the later. As the conclusion, the no-tillage treatment can be described as a treatment being less susceptible to compaction. However, consecutive implementation of this tillage treatment might require subsoiling operations every few years to disturbed the deep subsoil hard pans.