Design and Experimental Evaluation of a Narrow-Strip Tillage Device for a Maize Interseeder in Wheat-Maize Relay Intercropping

To address the restricted operating space in reserved maize sowing strips, surface soil compaction, the poor trafficability of conventional tillage machinery, and the risk of disturbing adjacent wheat rows under wheat–maize relay intercropping in Xinjiang, a front-mounted narrow-strip tillage device for a maize interseeder was designed. The device comprises a rotary tillage assembly and a soil-lifting device. An IT225 rotary blade was selected, and the structures of the rotary tillage assembly and the pointed-shovel soil-lifting device were designed. Kinematic and force analyses established operating ranges of 3–5 km·h−1 for forward speed, 240–360 r·min−1 for blade-shaft rotational speed, and 80–120 mm for rotary tillage depth. A discrete element model of the soil–tillage device interaction was developed in EDEM. A three-factor, three-level Box–Behnken experiment was conducted with forward speed, blade-shaft rotational speed, and rotary tillage depth as factors and soil fragmentation rate and soil bulk density as responses. Quadratic regression models were developed using Design-Expert and subjected to constrained numerical optimization. Both regression models were highly significant, whereas their lack-of-fit terms were nonsignificant, indicating good predictive performance. The optimum combination comprised a forward speed of 3.88 km·h−1, a blade-shaft rotational speed of 348 r·min−1, and a rotary tillage depth of 120 mm; the corresponding predicted soil fragmentation rate and soil bulk density were 92.40% and 1.38 g·cm−3, respectively. Field validation produced a soil fragmentation rate of 93.64% and a soil bulk density of 1.35 g·cm−3; the corresponding relative errors were 1.34% and 2.17%, respectively, both below 5%. These findings provide a basis for the design and operating-parameter matching of tillage components for maize interseeders used in wheat–maize relay intercropping in Xinjiang.