Investigation Tine Type Effect on Soil Fragmentation for Conservation Tillage

One of the main aims of tillage operation is to provide a seedbed with appropriate soil fragmentation and to create relatively large aggregates of topsoil to achieve conservation tillage. Considering that subsoiling is necessary for hardpan breakup, the creation of a seedbed with the same operation can increase the operation efficiency. The present study was conducted to investigate the effect of tine type on soil aggregate. For this purpose, we tested four subsoiling tines of conventional, Bentleg, Paraplow, and winged-Paraplow in the field at soil moisture contents of 8, 12, 16, and 20% and the tractor forward speeds of 0.5, 1, 1.2, and 1.4 m/s. Soil fragmentation was evaluated in different depths of 10, 20, 30, and 40 cm. Winged-Paraplow and Paraplow, compared with two other tools, showed more soil disturbance due to having a wing and chisel at the end of the tine. The highest mean weight diameter (MWD) =19.9 mm was reached using a Bentleg at a depth of 10 cm and moisture content of 20%. In comparison, the lowest value of 3.37 mm was related to the winged-Paraplow at a depth of 40 cm and moisture content of 8%.Considering the aggregate size of 0.5-8 mm for providing a proper seedbed, the winged-Paraplow tine is a suitable tool that can provide seedbed at any depth at a water content of 0.8PL, where PL denotes plastic limit. At slow forward speeds, fine particles had enough time to sift to a deeper layer, which is beneficial for seedbed creation. Reducing the soil moisture increased soil disturbance and its fragmentation. Moreover, it was observed that MWD was higher at high moistures..