The studies on deep tillage by using power-driven disc plow and deeper rotary have been carried out for the purpose of establishment of deep tillage in paddy fields and rotational fields.
In the case of paddy fields, the depth of 18cm were obtained by use of power-driven disc plow in wet field conditions of moisture contents of 64%. The tilling power requirements were 20-25kW and the drawbar resistance were 2100-3200N. It was recognized that the field performance of planting in deep tillage by disc plow were differ little compared with tillage by usual rotary.
In the case of rotational fields, the limits of tilling depth by use of deeper rotary were 38cm. However the deep tillage of tilling depth of over than 38cm made a trouble that clayey soils were close-packed amid tilling blades. It was said that the deep tillage made a suitable soil profile of depth of plow layer of 30cm.