Fields in which crops are planted rarely have a homogeneous soil composition. Different soil types have a different ability to retain water, nutrients, pesticides, herbicides, etc. Consequently, if uniform application of fertilizers, pesticides, herbicides, and water is carried out, there will be a varied crop yield throughout a given field. This problem induced the development of customized soil and crop treatment, which has been a very high priority research area in the agricultural industry over the last decade.
Early attempts at customizing soil and crop treatment involved manual plotting of the field, monitoring of soil type and condition, and yield monitoring. Of late, field mapping has become substantially more sophisticated. Computer assisted mapping techniques, together with satellite tracking, are commonly used. Crop yield can now be very precisely mapped.
A critical aspect of field mapping is the accurate monitoring of the crop yield. Heretofore, a wide range of different techniques and systems have been developed to monitor crop yields. One such system is described in detail in U.S. Pat. No. 5,282,389 to Faivre et al. entitled APPARATUS FOR MEASURING AGRICULTURAL YIELD. The system described in the '389 patent includes a structure for measuring flow pressure of conveying clean yield product and for converting this pressure data to a meaningful flow rate signal to generate a field yield map. The disclosed structure includes an actuating arm or probe, mounted such that it intercepts clean yield product discharging from a grain elevator on the combine, and adapted to produce a signal indicative of a pressure being applied to the actuating arm by the clean yield product. This pressure value can be correlated with other data, i.e. combine width, elevator speed, ground speed of the crop processing apparatus, etc., to generate a flow rate value that can be continuously plotted to generate a yield map for a field.
The signal producing structure disclosed in the '389 patent includes a strain gauge coupled to the actuating arm or probe to detect the pressure applied on the actuating arm or probe by the conveying clean yield product. Systems such as the one disclosed in the '389 patent have been found to have certain features which disadvantageously effect the flow sensor's operation. For example, the available flow sensor probe or actuating arm impact surfaces demonstrate inadequate flow sensing during inclined operation and during periods of operation with low flow. Thus, while harvesting a crop on an inclined surface or at slow speeds, or during low flow harvesting, the flow sensor accuracy is adversely effected. Further, occasional bending of the actuating arm or probe has occurred during use, also adversely effecting operation of the flow sensor.