Cumulative mass determination for yield maps of non-grain crops

Yield mapping, to date, has been achieved principally by the use of grain f low measuring systems in conjunction with ground positioning systems (GPS) that can be permanently fitted to combine harvesters. Mobile or tractor mou nted GPS systems are now becoming available so presenting the opportunity t o use different sources of information for crop yield data. A yield mapping system has been developed for use in non-grain crops (i.e. roots and forag e) using the measurement of mass accumulation rate. The concept was realise d by instrumenting a high-sided trailer to allow the rate of accumulation o f crop mass to be: recorded as the trailer follows the harvester. The locat ion of the trailer is recorded using a differential GPS with a linked data set to log the position and the processed mass information. To remove unwan ted noise due to trailer pitch, roll and yaw, and the tractor engine vibrat ions, the crop mass data are conditioned using a combination of analogue si gnal filtering and subsequent numerical processing. The results of field ha rvests for which yield maps were produced give confidence that the principl e of mass accumulation rate can be used in a range of harvesting machines a nd trailers. A yield map obtained for a forage crop showed a mean yield of 32.8 t/ha with a range from 26 to 35 t/ha. The mean yield values from the y ield map and from samples measured by batch harvesting were not significant ly different. Yield maps for single crops of sugar beet and potatoes showed yields between 11 and 68 t/ha (mean 49 t/ha) and between 10 and 50 t/ha (m ean 35.9 t/ha), respectively. For the sugar beet crop there was no signific ant difference between the mean yield values for batch weighed samples and recorded yield map values. (C) 1999 Elsevier Science Ireland Ltd. All right s reserved.