Soil tillage fragmentation efficiency for paddy soil with subsoiling

Subsoiling is an important method in conservation tillage, but it requires a lot of energy. In order to explore the energy distribution of tillage-induced soil fragmentation, soil tillage fragmentation efficiency was proposed to represent the ratio between energy consumed by soil fragmentation and energy input by tillage. A self-made multi-functional in situ test rig facility was used. The energy consumed by soil fragmentation was calculated by multiplying total area of soil fragmentation by specific surface contacting energy. The total area of soil fragmentation in the field was quantified by combining three complementary techniques, the sieve method for small aggregates (∅<64 mm), the camera method for large aggregates (∅≥64 mm), and the clone powder pouring method. The specific surface contacting energy was obtained by falling weight test. In addition, a digital cone-penetrometer was used to obtain contour of soil penetration resistance and a pin-type profilometer was used to calculate the cross-sectional area. The results showed that the draft force and specific draft increased with increasing tillage depth, reaching a maximum at a tillage depth of 20 cm. The specific surface contacting energy increased exponentially with soil depth. The cross-sectional area, total area of soil fragmentation and soil tillage fragmentation efficiency showed a trend of first increasing and then decreasing with an increase in the tillage depth, and reached a maximum at a tillage depth of 20 cm. The contour of soil penetration resistance before the experiment showed that the plow pan was located at a depth of about 15 cm.