The Impact of Conservational Tillage Systems on Some Physical Properties of Silty Clay Loam Saline Soil

The large area of saline soils in Iran and decreasing in quality of these soils require that the effectiveness of conservation tillage systems in such lands be investigated. This project aims to determine changes in soil physical properties in three different types of tillage system and plant residue management, including: 1) conventional tillage system and removal of crop residues from soil surface, 2) reduced tillage system and preservation of crop residues, and 3) no tillage system and preservation of crop residues in rotation of barley and safflower in a saline soil with irrigation water salinity of 5.35 dS/m for four years. Some soil physical properties such as bulk density and porosity, and aggregate stability indices of mean weight diameter (MWD) and geometric mean diameter (GMD) were measured in soil samples prepared from the layers of 0-10, 10-20 and 20-30 cm. After each crop rotation period, water infiltration into the soil was measured and the modified Kostiakov model was fitted to obtain the optimized parameters. The results of variance analysis of the data in the four years of the experiment showed that the difference in most of the soil properties at the end of the experiment was significant due to the tillage treatments compared to the control. The highest MWD and GMD (2.53 and 1.90 mm, respectively), porosity (51.2%) and final infiltration rate (31 cm/h) were observed in the no-tillage system. while the lowest MWD and GMD (2.02 and 1.29 mm, respectively), porosity (47.8%) and final infiltration rate (3.5 cm/h) were recorded in the conventional tillage system. Overall, our findings showed that the increment in the soil organic matter due to the implementation of conservational tillage treatments improved the stability of soil aggregates and increased soil porosity and water infiltration into the soil.