We have developed an electrostatic pesticide spraying system for low-concentration, high-volume applications to reduce vegetable production costs through savings in agricultural chemical usage and working hours for pest control. The electrostatic spray charging device (ESCD) has an outer annular induction charging electrode around a hydraulic nozzle with a high flow rate. The charge-to-mass ratio of spray droplets was -0.30 to -0.45 mC/kg at +4 kV, using a hollow-cone nozzle with a high flow rate delivering 1.0 to 2.6 L/min. No discharge or electric leakage occurred from the electrode. Using this device, we developed two types of sprayers. One type was an electrostatic boom-type sprayer for cabbage vegetables. Field tests showed that this boom-type sprayer reduced the amount of required pesticide application by 30% as compared to the conventional method. The other type was a spraying robot for greenhouse melons. There was no significant difference in the control of insect pests between robot spraying and the conventional manual spraying method. The effective field capacity of the robot was 3.8 a/h.
a b s t r a c tMethod of manual removal of produce from the field has been a bottle-neck for lettuce production in Japan. In order to reduce the production cost of this fresh commodity, a prototype harvester has been developed for head lettuce production. The harvester consists of a cutting component to slice the lettuce head at the desired location and a lifting component that transports the harvested produce from the cutting site onto elevating conveyor and trimming station. A cutting component with reciprocating blade was proposed.Laboratory tests were performed to verify ability of reciprocating blade to slice lettuce stump at forward cutting speed of 0.1 m/s, reciprocating stroke of 18 mm, and different reciprocating frequencies of 2, 4 and 6 Hz. In addition, power requirement for reciprocating the cutting knife as slicing two lettuce stumps was measure. Tests in lettuce fields were also conducted at different working speed to investigation the cutting and lifting performances of the harvester mounted with the reciprocating-blade cutting component. The results of laboratory tests indicated that the cutting component could smoothly cut lettuce stumps and the maximum cutting torque and cutting power requirement were 0.73 Nm and 27.7 W, respectively at 6 Hz reciprocating frequency. Field test results showed that the harvester could cut and lift the lettuce heads without damaging and blemishing the produce at working speed of 0.04 m/s and the commercial head percentage was 94.5%. At higher working speed of 0.08 m/s, the head damage rate was 12.8% reducing the percent of commercially accepted heads to 87.2%.
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