Site specific crop management involves closely monitoring the local environment and determining crop input needs for each portion of the field to economically optimize crop yields and reduce adverse environmental impacts of the production system. A key measure in this system is yield information determined by crop yield monitors. Current seedcotton yield monitors use optical and microwave sensing techniques to measure yield. However, the cotton yield monitors based on light emission require regular cleaning during the season and the microwave-based systems are expensive. The objective of this study was to test the use of velocity pressure to measure cotton-mass flow. The eventual goal is to provide an alternative approach for cotton yield monitoring. A cotton-harvester yield monitor concept was developed based on the relationship between air velocity pressure and the mass of seedcotton conveyed. The sensor was tested on a stationary cotton picker with seedcotton at two moisture contents, 5.9% and 8.5% wet basis. Regression analysis on the means of the data signals resulted in a coefficient of determination of 0.43 for the lower moisture content and 0.84 for the higher moisture content. Frequency and moving average filters were applied to the signals but did not improve the correlation. A method of compensating for gaps in the material stream resulted in an increased coefficient of determination of 0.52 and 0.87 for seedcotton at a moisture content of 5.9% and 8.5%, respectively. These results indicate the potential of air velocity pressure as an alternative approach for cotton yield monitoring.
