Evaluation of the performance of very narrow tines with different geometrical structures for tilling natural grassland

Abstract

Natural grassland is an important ecological barrier in northern China and using mechanised improvement methods to restore degraded natural grassland is significant. This paper aimed to evaluate the working performance of different very narrow tines through full-factorial experiments, and provide basic references for design novel and specialised tillage tools applicable to natural grasslands. The thickness, cutting edge angle, and rake angle were chosen as the independent variables, and related working resistance and soil disturbance indicators were selected as the dependent variables. Different shank-type tines and a test bench were designed and manufactured. Field experiments under different working depths were conducted. The results showed that the thickness, rake angle, and cutting edge angle all had statistically significant influences on the working resistance (P < 0.05), and interaction functions were found between these three factors. The soil overturning rate, soil bulkiness value, and soil disturbance coefficient created by the tines were in the ranges of 0.5–14.5%, 12–40%, and 50–68%, respectively. The tine with the thickness of 14 mm, the rake angle of 45°, and the cutting edge angle of 60° provided the best working performance. The grassland surface disturbance situation, soil overturning rate, disturbed cross-section area, soil bulkiness value, and soil disturbance coefficient well described the disturbance situation. The working depth and geometrical parameters of the tines all had influence on the working resistance and soil disturbance which should be considered together as the evaluation factors of the working performance of special tines for tilling natural grasslands. • Thickness, rake angle, and chamfer angle all significantly affect working resistance. • Soil disturbance coefficient of the grassland produced by shank-type tines is 50–68%. • Shank-type tine with chamfers cause low soil disturbance and small roots' damage. • Having cutting edge or not causes big differences in the soil overturning rate. • Rake angle of 45°, chamfer angle of 60°, thickness of 14 mm are optimum combination.