Prominent problems and thoughts of "paddy soil-terrain machine system" based on disturbed saturated paddy soil conditions in South China

There is a large number of paddy fields in South China. During rice sowing and transplanting, agronomy requires the topsoil to be soft, viscous, muddy, mixed with water and disturbed-saturated mud, after soaking, tilling and rotary harrowing. At this time, the soil has a high fluidity, high adhesion and low shear strength. Thus, it would be productive to research the contact relationship between the soil contacting parts and the soil surface, so as to improve the operational efficiency of the tillage and planting machinery of paddy field in this soil condition. For this purpose, the disturbed-saturated soil formation process is described, the coupling mechanism between soil-engaging components and such soil conditions is clarified and the current state and prospects of research on soil-tool interactions under paddy field conditions is analyzed. This paper is expected to serve as a useful reference for future work in studying the surface characteristic parameters of soil contacting parts; the coupling correlation mechanism of "contact-rheologyresistance" among the structural shape, motional parameters and the disturbed paddy field soil, creating favorable conditions at the soil-tool contact interface for drag force reduction in the paddy field soil, the design and the optimization of paddy field equipment in South China, and the research on the technology of reducing viscosity and drag force of paddy field machinery.