Research progress in the technology and equipment for potato mechanized harvesting and impurity removal

Potatoes have been widely used as food and vegetable, due to their drought resistance to low soil fertility, high water use efficiency and economic benefits. The potato industry is of great significance to ensuring national food security in poverty alleviation. Efficient and low-loss impurity removal can be one of the most important links in the mechanized harvesting of potatoes. The models and equipment of harvesting can be expected to promote the quality of potatoes. However, the planting and harvesting patterns of potatoes are varied greatly under different natural environments in each region. The various demand is required for the impurity removal, device structure and working principles for mechanized potato harvesting. It is very necessary for the device of seedling film impurity suitable for potato harvesting patterns in different regions. Furthermore, the potatoes often experience bruising or mechanical damage during movements, such as falling, impact, rolling, and friction, in mechanized harvesting. Therefore, the impact damage of potatoes can be expected to be explored during impurity removal. The innovative design and structural optimization of impurity removal devices are also important means to improve the performance of harvesting equipment. A tradeoff can be considered to balance the efficient impurity separation and low-loss harvesting. The research direction of potato impurity removal is how to separate the potato chunks from soil, seedlings, residual film, and debris, according to the harvesting of root and stem crops. This article aims to review the basic structure and technical status of the typical potato harvesters from the perspective of potato planting agronomy. A summary was also given on the membrane impurity treatment of mechanized potato harvesting seedlings, covering the device structure and working principle of potato soil separation, potato seedling separation, residual film recovery, and impurity cleaning. A comparison was then made to evaluate the technical indicators of different impurity removal devices. In response to the plastic film planting and soil viscosity in hilly areas in China, the influencing factors were proposed for potato impurity removal, including uneven development in different planting areas, large differences in mechanization level, difficulty in handling seedling film impurities, significant damage to potato harvest, and the need to improve mechanical technology and manufacturing level. A standardized and unified potato planting system should be established in the same planting area. The planting types were then recommended to reduce the cost of impurity removal in potato harvesting. Much attention can be pained on new technologies, such as sensors, electro-hydraulic control, image processing, machine vision, intelligent measurement and control. New structures and overload protection can be utilized to reduce the loss of the material in the key technologies of impurity removal. Advanced electromechanical, hydraulic and pneumatic technologies can be applied to improve the performance and reliability of products. The intelligent, precise, and information-based agricultural equipment can be focused on the key technical challenges, such as intelligent control, loss reduction, cost saving and high efficiency. New technologies, materials, equipment, and processes can greatly contribute to the mechanized impurity removal in potato harvesting.