Authors changed the number of tines from 16 to 32 and the speed of rotary shaft from low or medium to high in a rotary tiller of 55cm width.
The tests were carried out on the paddy fields after harvestig at Miyazaki, Okayama and Miyakonojo. These tests have been done in connection with the increment of cut (number of tines, speed of rotary shaft, foward speed), tilling depth, number of tillings, and moisture content of soils.
The result was as follows;
(1) Between 32 tines and 16 tines in the same lead, the pulverizing action of 32 tines was larger than 16 tines, and the coefficient of surface area of 32 tines was larger than 16 tines when the moisture content of soil was little. But when the moisture content of soil was high, the soil pulverizing ratiounder 1cm of 32 tines was smaller and the rat ioabove 4cm was almost same compared with 16 tines.
(2) Generally, the action of pulverizing of small increment of cut was excellent when the moisture content of soil was little, but not so good when the moisture content was high.
(3) Pulverizing action in tilling depth of 5cm was larger than in the depth of 10cm at the same increment cut.
(4) Power repuirment of the rotary shaft at speed of 0.4m/s was frequently over 5 ps and less than 0.5 ps at 0.2m/s.
(5) Tilling volume per horsepowerhour of 32 tines showed 10-20% decrease compared with that of 16 tines.
(6) Pulverizing action was excellent when the increment of cut of second tilling was small in double tilling.