Effect of subsoiling on soil physical properties and sunflower yield under conditions of conventional tillage

This study was carried out to investigate the effect of using a subsoiler for conventional tillage on some soil physical properties and sunflower yield. The research was carried out in the Kabootarabad Research Station (23 km south-east of Isfahan). The experiment was performed using randomised complete block design with 3 replications. The treatments were (T1): conventional tillage + flat planting, and (T2): subsoiling + conventional tillage + flat planting. Cone index, bulk density, infiltration rate, root length, plant height, stem diameter, sunflower head diameter, seed yield, thousand seed mass, plant dry mass and oil content were measured. The results indicated that bulk density and cone index values were not statistically different while water infiltration rate values in subsoiled land were significantly higher than those of unsubsoiled land. It was also found that subsoiling did not affect sunflower yield, so from economical standpoint it is not recommended to use it in irrigated sunflower production in the area studied. Finally, it is concluded that subsoiling can be used when there is sever plough pan or hard pan within underlying soil layers which causes restricted root development.