Abstract
The field performances of 3 types of intra-row weeders were evaluated. The field tests were conducted between 1991 and 1993 in the fields of 4 crops, viz. directly sowed sugar beets, transplanted sugar beets, azuki beans, and navy beans.
1) In the case of the directly sowed sugar beets, the rates of weed extermination were between 72 and 75%. This was due to the fact that the first weeding operation before the crops emerged could not be performed, and each weeder could not give strong weeding action to the weeds, because the weeds and the crops were the same toughness in the early weeding season.
2) In the cases of the transplanted sugar beets, azuki beans, and navy beans, the rates of weed extermination were over 90% for each weeder, except for the test conducted at Kiyokawa which was hampered by rainy weather which continued in the early weeding season. Mechanical damage to crops was minimal for each weeder, and no significant difference in the yields was observed between both weeding systems of the intra-row weeder and the traditional method.
3) The number and the intervals of optimum weeding operations for each crop were considered to be more than 4 times with 7 to 9 days interval in the weeding season for each weeder.
4) The range of the estimated field capacity was approximately 0.5-1.1ha/h for each weeder.
