Field experimental study on pullout forces of rice seedlings and barnyard grasses for mechanical weed control in paddy field

Pullout forces of rice seedling and barnyard grass were tested by universal testing machine controlled by WDW-5 type microcomputer to obtain the pullout forces of rice seedling and barnyard grass.The measured pullout force was used to improve the weeding rate and reduce the rice seedling damage rate caused by mechanical weeding device.According to the measured continuous curve of pullout forces of rice seeding and barnyard grasses in weeding period,the best range of force required to pull out barnyard grasses from soil with no injury and damage to rice seedlings was discussed.Reasons for the difference in the pulling force were analyzed.Results show that,with the increment of the number of single cell rice seedlings the pullout force increases.The pullout forces of single cell rice seedlings and barnyard grasses at first increased slowly reaching the maximum value followed by rapid drop and finally it remained steady.The minimum pullout forces recorded during rice seedlings at the first and the second weeding periods were 2.57 N and 9.70 N,respectively,while the minimum forces during the first and second weeding periods were recorded as 1.24 N and 7.51 N,respectively,for barnyard grasses.The results show that the pullout forces of weeding to rice seedlings and barnyard grasses should be within 1.24 N to 2.57 N and 7.51 N to 9.70 N respectively in the first and second weeding periods.

Review of non-chemical weed management for green agriculture

This paper reviewed the background and situation for studying and developing non-chemical weed management.Environmental pressure and commissariat safety problems indicate that it is essential to deeply study and develop non-chemical weed management technologies.The paper summarized the pros and cons of the non-chemical weed management technologies in aspects of weed control by agronomic method,mechanical method,thermal treatment method,and biological treatment,discussed the defects of the existing non-chemical weeding methods,and put forward some suggestions:(1)The description on the experiments and operation of the non-chemical weeding technologies is suggested to be standardized in order to compare the performance of different weeding methods.Some important information on name of equipment,consumption capacity,working width,travel speed,and weed control levels should always be included in the experimental descriptions;(2)An integration of combinations or sequences of various weed control techniques is suggested to be used to reduce the risk of a selective pressure leading to the predominance of certain species;and(3)It is also suggested for further improvement of the existing weed control methods and further development of the weed detection technology originally developed for precision chemical application in order to use them in non-chemical weed management.