As a conclusion of the series of studies aiming the minimum tillage resistance, the following suggestions have been made.
1.
The basic tillage methods: Straight, rotary and vibratory tillage were studied and compared each other from the view point of tillage resistance and energy. Considering the degree of soil pulverization, the vibratory method is, generally, the most favorable for minimum resistance and small energy. Straight cutting method is the second.
2.
Blade shape and motion: The favorable factors relevant to blade shape are; small cutting angle, convex surface, discontinuity (like slat moldboard plow), certain types of cutting line and dimension of blade. Freedom of blade motion (like free rotating disc), low cutting velocity, cutting action towards free surface of the soil are preferable among motion factors.
3.
Soil and tillage method: Each tillage method includes different amount of cutting, shearing and tensile action of soil failure, A favorable way of breaking soil is to be varied according to the soil properties. Consequently, there must be a favorable tillage method according to the soil type and conditions. For example, a tillage method including much cutting action is suitable for clay soil, whereas, shearing action is more important for sandy soil.
4.
New tillage method: A factorial classification of existing tillage method shows that there are quite many lost links of the chain of tillage machines which might be more preferable for minimum tillage energy. By introducing favorable factors above mentioned into these lost links of chain, better tillage machines will be developed.
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