JOURNAL of the JAPANESE SOCIETY of AGRICULTURAL MACHINERY

To elucidate the practical scale of a movable bench system for strawberry cultivation, we investigated harvesting efficiency using the system. Our results indicated that working hours required for harvesting per cultivation bed depended on the number of mature fruits. If there were relatively few fruits, the working hours depended on the cycle time of the system. In contrast, if there were many fruits, the working hours, which increased in proportion to the number of fruits, were affected by the picking and placing speed of the operator. It also appeared that the maximum practical scale of the system was approximately 770m² with two operators.

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With the aim of burying surface field soil that may include radioactive materials, the burial of the top 3 cm surface layer soil by 22-inch and 14-inch moldboard plows was investigated in andosol and gray lowland soil upland fields. The following results were obtained. (1) The average buried depth of surface layer soil was proportional to the plowing depth. (2) The estimated average buried depth of surface layer soil after the plowed soil had settled to its pre-plowed level was about two-thirds of the plowing depth. (3) The 10th percentile of the above-mentioned estimated average buried depth of surface layer soil was about a half of the plowing depth.

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We developed a direct-mounted-type hiller to use wide-row taro fields in Miyazaki, Japan, and examined the relationship between the test conditions and power-take-off (PTO) torque. Although earthing up height was linearly correlated with tilling depth, earthing up height was not correlated with the tilling pitch and was fixed. PTO torque was relative to tilling depth, tilling pitch, and the amount of tilling. PTO torque was not expressed by only a linear expression. Multiple regression analysis of PTO torque and tilling depth, tilling pitch, and soil density showed that the standardized partial regression coefficient was large in the order of tilling depth, tilling pitch, and soil density.

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A compact pulsed power generator was developed as an electrical stimulation system for improving fruiting body yields of edible mushrooms. The pulsed power generator was designed based on an inductive energy storage system that minimises size and weight. The output voltage of the pulsed power generator was varied from 50 to 130kV with a 100ns pulse width to determine the optimum amplitude. The output voltage was applied to a sawdust-based culture of Lyophyllum decastes, and bedlogs hosting Lentinula edodes, Pholiota nameko, and Hypholoma sublateritium. The experimental results showed that the fruit body formation for some kinds of mushrooms increased 1.3-2.0 times as measured by total weight. The accumulated yield of Lentinula edodes for four cultivation seasons was improved from 160 to 320g by applying voltages of 50 or 100kV. However, the yield was decreased from 320 to 240g with increasing applied voltage from 100 to 130kV. The yield of the other kinds of mushrooms showed similar tendencies to the yield of Lentinula edodes with applied voltage. These results show that an optimal voltage is needed for efficient fruit body induction.

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