Effects of Different Methods of Tillage on Some Physical Characteristics of Soil

Seed bed preparation is the first important step in planting each crop. This study was conducted in order to investigate the effects of three different tillage methods (T1: moldboard plow, T2: subsoiler, T3: subsoiler with decompactor) at two depths on some physical propertiesof a soil classified asfine mixedthermic typic Haploxereptswith silty clay texture. A factorial experiment in a completely randomized block design and three replications was performed at Sari Dashtenaz Research Farm in 2011. Results showed that the lowest bulk density was observed when subsoiler was used and the maximum was related to the moldboard plow. Interaction of soil depth and tillage method had significant effect on porosity. As to soil water retention capacity, there were significant differences among treatments such that the subsoiler and decompactor had the maximum amount of soil water retention capacity. With regard to field capacity and permanent wilting point, there were significant differences between treatments and the highest effect was related to the subsoiler and decompactor, which were almost equal to moldboard plow. In addition, the plot where subsoiler and decompactor were used had the highest amount of available water for plants. With respect to the aggregate stability, it was observed that there were significant differences between treatments: the use of moldboard plow had the highest stable aggregate and the lowest was related to sub-soiling with decompactor.Sub-soiling and sub-soiling with decompactors treatments compared to moldboard plow reduced cone index. In addition, results showed that sub-soiling increased the infiltration rate of water into the soil.