In this research, estimation of nitrogen content models at panicle initiation (40 plots) and heading stages (22 plots) and validation of models at heading stage (18 plots) were investigated using multi and hyperspectral remote sensing, depending on two test fields of different nitrogen fertilizer application. On the test field 1, nitrogen fertilizer was applied with seven nitrogen treatments at both basal dressing and topdressing. On the test field 2, nitrogen fertilizer was applied with seven nitrogen treatments at basal dressing and by variable rate at topdressing depending on the plant growth. By using multispectral images recorded at each vegetation stage, it is possible to create nitrogen content models using Green NDVI, as 0.908 and 0.775, respectively. By using hyperspectral image recorded at panicle initiation stage, it also possible to create nitrogen content models using multilinear regression (r=0.958, MLR) and partial least square regression (PLS) methods, such as Leverage method (r=0.912) and Full-Cross method (r=0.895). In the case of heading stage, Leverage method (r=0.999) and Full-Cross method (r=0.909) were better than the MLR method (r=0.805). When these models were compared at each vegetation stage, there were similar results as nitrogen content models of Green NDVI (RMSEC=0.610), MLR (RMSEC=0.718), PLS analysis (RMSEC=0.430, RMSEC=0.470). At heading stage, however, there were different tendency at nitrogen contents models compared with Green NDVI (RMSEC=1.808, RMSEP=1.468) and MLR (RMSEC=1.697, RMSEP=2.208) with leverage method (RMSEC=0.083, RMSEP=4.344) and Full-Cross method (RMSEC=0.706, RMSEP=2.494) of PLS, which was better at RMSEC, but worse at RMSEP and maximum error.

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The objective of this research is to develop a field improvement based on methodology for working chracteristics on harvesting, and GIS maps using terrain information. To generate a GIS map based on the working chracteristics on harvesting and terrain information, location of the field is essential; therefore a real time kinematical global positioning system (RTK-GPS) was used to provide terrain information and also the vehicle's absolute positions. An inertial measurement unit (IMU) was used to provide posture (yaw, pitch and roll) of the tractor. The system was built on a robot tractor modified a 56kW tractor. As the result, the area where work characteristics have to be improved was identified automatically by the discriminant analysis using explanation variable of synthetic vector and inclination angls.

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Soil compaction methods used before sowing were investigated in order to obtain sufficient sugar beet emergence rate. When lowland soil was compacted using a combination of cultivator and packer and rollers of a rotary harrow, they provided a cone index of 1.0MPa with a depth layer between 10cm and 20cm, an emergence rate of 85% was successfully achieved. The combined use of cultivator and packer showed 1.5kW bigger PTO shaft power during rotary harrowing than the use of a disk harrow. In the case of wet andosol soil that was compacted twice using a combination of cultivator and packer, an impermeable layer was formed and the yield obtained was poor. The combinations of clods less than 4.75mm in diameter and cone indexes with a depth layer between 10cm and 20cm that yielded an emergence rate of more than 85% were as follows: 1.0MPa and/or more at 58% clod; 0.9MPa to 1.0MPa at 60%, and below 0.9MPa at 65%, respectively.

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We clarified the firmness property and the load effect on the quality deterioration of strawberries to assist in the development of handling and packaging methods that prevent damage to the fruit. With samples of “Tochiotome” strawberries harvested from December 2005 to May 2006, we measured the firmness of various parts of the fruit classified according to color, and found that the apex and equatorial part of 80% colored or full colored fruit had almost equivalent firmness. Regarding the relation between the load and quality deterioration, we found that a load could cause color change even when the load-induced deformation at the apex was only 0.2mm. We also found that the color of the fruit tended to change significantly when the applied load became larger. It was also verified that even a temporary load could affect the subsequent quality change of the fruit.

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This research aimed to develop an automated cleaning machine for dressed carcasses that would be capable of washing processed meats safely and effectively while maintaining meat quality. To evaluate the effectiveness of several nozzles water or a lactic acid aqueous solution was sprayed on meat samples. Results indicated that when the painted meat sample using the commercial black paints was washed, nozzle number 8002 (discharge rate 1.4L/min) with a water pressure of 0.98MPa or more and with a spray distance of 70cm was able to wash the painted meat in 30 seconds. The tests also showed that washing the meat coated with brain tissue of the ruminant (Sika Deer) had a washing characteristic similar to that of washing the painted meat. Furthermore, washing the coated the brain tissue using the lactic acid aqueous solution was more effective than washing with distilled water.

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When proportional solenoids driven by pulse width modulation (PWM) are employed in electromagnetic proportional control valves of tractor implements for agricultural applications, the suction force characteristics of the proportional solenoid vary with the oil temperature and supply voltage in the same duty cycle. This means that the valve produces a variety of different outputs for any particular operation signal depending on the temperature and voltage. This variation in the output makes operation of tractor implements problematic. To suppress these characteristic changes, we modified the PWM drive duty and compensated the electric current so that the average supply electric current to the solenoid was proportional to the operation signal. We describe a method of compensated electric current control and a selection method for weight coefficients suitable for tractor implements, in which the operation signals are changed frequently making it suitable for agricultural applications.

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