LTER Agronomic Grain Yield and GIS Yield Monitoring

Halvorson, M.

Presented at the All Scientist Meeting (1998-07-21 to 1998-07-22 )

Agronomic yield is evaluated for each of the annually tilled cropping systems each year. The annual cropped systems are in a corn-soybean-wheat rotation. The annual cropped treatments are replicated six times and include Treatment 1, CT-Conventional Chemical Input/Conventional Tilled, Treatment 2, NT-Conventional Chemical Input/No Tillage, Treatment 3, LI-Low Chemical Input/Conventional Tillage, and Treatment 4, ZI-ZeroChemical Input/Conventional Tillage. Differences in cropping systems and how each is managed influence final grain yield (Fig. 1).   Since 1996 grain yields on the LTER site have been estimated using a Global Positioning System (GPS). The GPS uses 24 earth orbiting satellites to determine the JD 4425 Combines location during the harvesting operation with sub-meter accuracy. The coordinates are added to yield information in 1 second intervals and this data is used to generate yield maps following the harvesting operation. The yield monitor within the combine is connected to various electronic sensors within the combine and is calibrated prior to harvest for each crop. The yield monitor gives accurate on the go information to the combine operator during the harvest operation and this data is recorded and downloaded to a computer at the end of each harvest day. In 1998, all four treatments were evaluated for wheat yield across all six replicates; grain weights compared to actual grain weight by plot had generally less than 2% error. In 1996-corn and 1997-soybean harvests, the first four replicates of all four treatments were recorded (some of reps 5 and 6) using the yield monitor. The 1996 yield monitor data has been corrected for moisture and grain yield by plot and re-mapped. The 1997 data is still being processed and we’re just beginning to look at the 1998 data. The JD 4425 combine will be available for demonstration and yield maps for Treatment 3, Replicate 3 for 1996-corn, 1997-soybean, and 1998-wheat appear in Fig. 2 and in Fig. 3. These maps demonstrate similar yield treads for a location and across years for different crops. These similarities show how changes in soil type influences final grain yields and these differences can also be picked up by looking at the low level infared fly-over photographs taken each year prior to harvest.Return to Contents

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