Performance evaluation of a biomimetically designed disc for dense-straw mulched conservation tillage

Abstract

High-yielding agriculture leads to dense straw cover (mulching). Soil-engaging tools for conservation tillage in these scenarios demand enhanced tool performance, e.g., improved soil penetration, reduced force requirement, better straw cutting and minimised soil disturbance. These interdependent and yet conflicting performances could not be easily realised with traditional tillage tools. Instead, biomimetic tool design could provide a compromised solution. A biomimetic disc mimicking the mole-rat’s claw was fabricated and evaluated in comparison with traditional discs (i.e. a plain and a notched disc) in straw-mulched soil. Soil bin tests on the 3 discs were conducted at 3 tillage depths (i.e. 40, 70 and 100 mm). Results showed that the biomimetic disc achieved 21.4 % reduction in vertical resistance and 28.7 % reduction in draught forces, as compared with the notched disc (P < 0.05). Besides, the biomimetic disc achieved 8.5 %, 23.9 % and 12.0 % higher straw-cutting efficiencies than the plain disc, and 4.9 %, 11.7 % and 10.2 % higher cutting-efficiencies than the notched disc, over the 40, 70- and 100-mm depths respectively. The biomimetic disc also had the least soil disturbance rates across all the 3 tillage depths. The improved performances of the biomimetic disc were due to its optimised soil-engaging profiles that mimic the smooth, continuous and efficient working mechanism of the mole-rat’s claw. The claw-shaped edges easily penetrate through densely mulched soil while avoiding tool-sliding over the straw, and achieves minimum soil disturbance. The biomimetic tool design thus presents a viable solution for the conflicting performance requirements by conservation tillage in intensive farming systems.