Authors

Abstract

Winter potato cultivation in paddy fields in southern China can improve land-use efficiency and increase farmers’ incomes. However, compared with those in northern China, paddy soils in southern China are generally heavy, cohesive, and compacted, resulting in poor mechanized potato-harvesting performance and restricting the development of the potato industry. To improve potato-soil separation efficiency under heavy clay soil conditions, a twin-roll soil-crushing device was installed ahead of a conventional chain-and-rod potato-soil separation device based on the characteristics of clayey soils in southern China. This configuration formed a two-stage separation process involving soil crushing followed by screening. The soil-crushing process was theoretically analyzed, a discrete element model of the soil-crushing and screening device was established, and the soil-crushing and potato–soil separation processes were numerically simulated. Response surface simulation experiments were conducted using rib height, number of ribs, and twin-roll rotational speed as the experimental factors, with soil-screening efficiency and the maximum force acting on the potato tubers as the response variables. The results showed that the twin-roll soil-crushing device effectively disturbed and crushed the soil during operation. Increasing the rib height and twin-roll rotational speed enhanced the soil-disturbance and crushing effects. The optimal structural and operating parameters of the twin-roll soil-crushing device were a rib height of 30 mm, three ribs, and a twin-roll rotational speed of 323.70 r/min. A simulation verification test conducted using these optimal parameters yielded a soil-screening efficiency of 72.80% and a maximum force acting on the potato tubers of 15.45 N. Field-test results showed that the potato harvester equipped with the soil-crushing device achieved a tuber damage rate of 0.285%, a skin-damage rate of 2.38%, and a tuber loss rate of 3.18%, thereby meeting the requirements of the applicable national standards. These findings provide a reference and technical support for the development of potato-harvesting machinery suitable for heavy clay soil conditions.

Abstract in Chinese

中国南方水稻田冬种马铃薯能提高土地利用率，促进农民增收，但水稻田土壤黏重板结，马铃薯机械化收获作业效果不佳，制约了产业的发展。为了提高黏重土壤下薯土分离效率，本研究在传统链杆式薯土分离装置前设计了对辊式碎土装置，对碎土过程进行了理论分析，构建了碎土筛分装置离散元模型并对土壤破碎和薯土分离过程进行了数值模拟。以碎土装置的凸棱高度、凸棱数量、对辊转速为试验因素，以土壤筛分效率和薯块最大受力为评价指标，开展了响应面仿真试验，结果表明，对辊式碎土装置在工作时对土壤起到了扰动和破碎作用，增加凸棱高度和提高对辊转速能够增加碎土装置对土壤的扰动和破碎作用。对辊式碎土装置的最优结构运行参数为凸棱高度 30 mm，凸棱数量为 3 个，对辊转速 323.70 r/min，以此最优参数开展仿真验证试验，土壤筛分效率为72.80%，薯块最大受力为15.45N。田间试验结果表明，配置有碎装置的马铃薯收获机伤薯率为0.285%，破皮率为2.38%，损失率为3.18%，满足国家标准要求。研究结果能为黏重土壤条件下马铃薯收获机具的研发提供参考和支撑。