Effect of Conservation Tillage on Soil Moisture Conservation and Sunflower Yield under Rain-fed Conditions

In order to study the effect of conservation tillage on soil moisture conservation and sunflower performance at Shahrood area, along term experiments were carried out during four years in sunflower-wheat rotations.The experimental design was Randomize Complete Block design (RCBD) with four replications and five treatments. The treatments were chisel plowing in spring, moldboard plowing, reduced tillage with disk harrow, disk plowing and chisel plowing in autumn. Combined analysis of data showed that the effect of treatment were significant on crop yield and soil moisture content (at 5-20 cm depth) (P<5%). Maximum and minimum of soil moisture content and yield were obtained by chisel and moldboard plough, respectively. Soil inversion index difference was significant among the treatments (P<1%). Maximum and minimum of soil inversion index was related to moldboard and chisel plough, respectively. Soil organic carbon content difference wasn’t significant among the treatments (P<5%), but values for chisel and disk harrow were higher than those moldboard and disk plough. It is concluded that reduced tillage causes an improvement on soil organic content, soil water conservation and yield. Therefore, chisel plough is recommended as a best alternative for moldboard plough.