Effect of deep tillage on soil properties and wheat yield in the rain fed conditions

In order to evaluate the effect of sub-soiling on the soil physical properties and wheat yield in dryland conditions, this research was conducted in Mamassani area in the province of Fars for one year in 1388. The research was performed in the form of a complete blocks design with four replications. Treatments were 1) conventional tillage without using subsoiler (Control) 2) using subsoiler with the shank space of 40 cm (shank space equal to the subsoiling depth) 3) using subsoiler with the shank space of 60 cm (shank space equal to 1.5 times of the sub-soiling depth) and 4) using subsoiler with the shank space of 80 cm (shank space equal to 2 times of the sub-soiling depth). Sub-soiling depth was set on 40 cm which was the lower limit of the hard pan depth in the soil. Results showed that sub-soiling decreased the soil bulk density and cone index, and increased water retention in the soil. Results also revealed that applying subsoiler increased wheat yield and yield components in dryland conditions because sub-soiling improved soil physical conditions andincreased wheat yield. Results of this study also showed that sub-soiling with the shank space of 40 and 60 cm had better performance compared to the shank space of 80 cm. On the other hand, shank space of 40 cm reduces the subsoiler effective working width and effective field capacity. Therefore, shank space of 60 cm is recommended for subsoiler in the dryland conditions.