Journal of agricultural engineering research vol:55 issue:1 pages:1-10
Yield mapping may form an important part of an in-field site-specific crop production system, both for the spatial analysis of production efficiency and for the determination of spatially optimized application rates for fertilizer and sowing of seed. The objective of the work reported here, was to apply the principle of yield mapping to whole crop harvesting corn silage. The yield measurement is based on the continuous recording of the material flowrate through harvesting machine, the machine driving speed and the machine location in the field. For the flowrate measurement, the shaft of the material blower and the drive shaft of the base unit powering the cutterhead, feedrolls and front attachement, were instrumented with strain gauge torque transducers. Within the calibration range, the signals of these sensors showed a linear relationship to the flowrate. The harvester was also equipped with a speed radar and a data acquisition system based on a personal computer. The location tracking of the machine was done by integrating the machine speed and manual recording of the machine path in the field. The construction of a yield map, from the recorded signals, included several digital signal processing operations. The resulting map of a 1·2ha corn silage hield showed spatial yield variation from 1·2 to 4·8 kg/m2 with average of 3·2 kg/m2 and standard deviation of 0·64 kg/m2.