The author has classified those factors which some influences on the field work efficiency η of rotary tillage by tractors into 5 groups (shown in Tab. 1), and then investigated the degree of their influence by analysing the date obtained from 65 cases, the author had measured himself.
1. As for square fields the author studied the relation between the theoretical field efficiency η
th and the area of the field A and its length-ratio F. The author calculated the value of mechanical Characteristies of the tractor a and a/
l, from 65 cases above mentioned. During standard work, F showed less influence than a and a/
l did. Though A being expanded into more than 30 ares, η showed little improvement.
2. As for irregular shaped fields, the author thought out their equivalents in square-shaped field and calculated its length-ratio F, which the author called coefficient of shape of field and by which the irregular shaped field could be compared with other field with ease. Then the author applied this method to the 65 cases and got the value of F for each respectively. The value of F in irregular shaped field was very small in general, sometimes much smaller then 1. So the shape of the field was found to be more influential.
3. Theoretical efficiency η
th was calculated by applying A, F and a, a/
l to the 65 cases. The author measured the aberration ε between η
th and η, and calculated the theoretical aberiation ε
th by the regression line from A. As A becomes smaller, ε was proved to be larger, especially in irregular shaped field.
4. The difference of ε from ε
th might be called E, the difference of skill. The daviation of E was rather larger than expected, and moreover, it might be labelled as regional difference, individual difference and so on. The deviation of E was greator as A become smaller.
5. The value of η, under A, F and a, a/
l, could be guessed, within the range of deviation of E, by calculating η
th and then by adding ε
th to it.
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