A Procedure for GIS Analysis of Multi-Year GPS Based Yield Monitor Data

Agricultural research often involves measuring grain yields produced on research treatment plots. Those plots are most often harvested by hand or by research sized mechanical harvesters. The process requires weighing the grain harvested, determining grain moisture, measuring the dimensions of the plot, and making calculations to determine the yield in mass per unit area at standard moisture content for the grain harvested. In recent years commercial combines have been outfitted with grain mass flow and moisture sensors, global positioning systems (GPS) and micro-processors that compute point yield measurements at known locations throughout the harvest area. That type system was used to obtain yield data for a five- year research study comparing water table depth and tillage treatment effects on corn and soybean yield. A procedure was developed to collect and analyze the yield monitor data enabling yield comparison by experimental treatment. The procedure combines geographic information system (GIS) presentation of the yield data with coefficient of variability (CV) analysis to assess the accuracy of the yield data. The procedure resulted in data that appears to accurately allow comparison of yields for single years but not between years.