YIELD DETERMINATION OF FORAGE CROPS BY ROUND BALERS PRESSING

Yield mapping is one of the basic elements of the precision agriculture system. Different sensors and systems which are placed directly on harvesters are commonly used for yield mapping nowadays. Concretely for straw and forage crops yield mapping, the sensors are placed on mowing machines or choppers. Another possibility could be the weight of the whole harvester or transport machine such as pick-up balers or wagons. This idea is very simple but the practical application brings together technical and organizational problems. The technical solution for forage crops and straw yield measurement consists of a simple arrangement of a position sensor - potentiometer mounted on the belt tension roller on the chosen round pick-up baler with a variable chamber. A rotary press with the variable chamber VICON RV1601 Opticut was used for the measurements. Wheat straw and hay was pressed during the trial measurement. The position of the belt tension roller was monitored by the potentiometer. The numbers of pulses from the potentiometer corresponded with the position of the measuring belt tension roller during the chamber filling. Calibration of the measuring system showed a strong dependence of the tension roller position on the amount of the pressed straw or hay (R=0.99). Finally, the yield map of straw and hay was created. The technical solution consists in the arrangement of the tensioning mechanism for tracking a variable compression chamber of the press during molding of forage or straw into the bale. To measure the Baler VICON RV1601 OPTICUT was used. During the trial measurement wheat straw and hay were pressed. The location tensioning mechanism was monitored with the potentiometer. The location potentiometer is shown in Figure 1. Detailed description of the engagement and solution demonstrates the utility model CZ 19754 U1. The outputs from the potentiometer are pulses. A specially designed electrical circuit was connected with the potentiometer and DGPS receiver. The data were recorded every two seconds. The system must be also calibrated. Before calibration a line was created punctuated with 10 m line of straw with 10 m break without straw. Ten-lines were considered. Thus, gradually the bale was developed. For each line there was pulse reading, which corresponded to the position of the tensioning mechanism for the gradual implementation of the bale chamber.