Prediction of the Trafficability of the Tractor on the Soft Paddy Field (II)

Cone Index and the Soil Hardness by YAMANAKA'S Meter

Abstract

It was confirmed by the last test that the cone penetrometer developed by the Waterways Experiment Station will be available to predict the trafficability of the tractors on the soft paddy field. So far, in our country, many same kinds of the cone panetrating devices has been used in agricultural field. Yamanaka's meter in Fig. 1 is the one of these soil hardness meters which was used mainly in the field of fertilizing improvement.
This test was attempted to know the relations of cone penetrometer and Yamanaka's meter and to find out whether the Yamanaka's meter will be available to predict the trafficability of the tractors or not.
The relations between the cone penetrating forces and the forces by Yamanaka's meter in kg/cm² and in kg/cm³ are presented by the broken curves C and D in Fig. 6. At the top layer of the soil surface, 0-10cm depth, the relation curve between the cone penetrating force in kg and Yamanaka's penetrating length in mm was similar to C or D curves, but in the deeper depth, the penetraing forces by cone increased as seen in Fig. 6, and the increasing rate of the forces to penetrate was the one kg. per five cm. It seems that the increasing of the penetrating force was due to the soil weight above that layer and friction force between the soil ahd penetrating rod.