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Why Sensors May Not Be Appropriate for Minnesota. Gyles Randall Univ. of Minnesota Southern Research and Outreach Center. NUE Workshop. Manhattan, KS. July 31, 2008. Challenges. Relatively high OM soils - capable of significant mineralization - delays NDVI discrimination (Algorithm)
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Why Sensors May Not BeAppropriate for Minnesota Gyles Randall Univ. of Minnesota Southern Research and Outreach Center • NUE Workshop. Manhattan, KS. July 31, 2008
Challenges • Relatively high OM soils - capable of significant mineralization - delays NDVI discrimination (Algorithm) • Rainfed agriculture • dry weather after SD limits N uptake • where are the roots? • MN BMP: apply SD N before corn is 12” tall (V7) • Split N application adds risk • Synchronizing technological diagnosis with agronomic response
Average NDVI, RI, and EONR as affected by N rate across 8 sites for corn following soybeans in Minnesota.
Average NDVI, RI, and EONR as affected by N rate across 6 sites for corn after corn in Minnesota.
Corn yield responses with mid to late sidedress N applications in southern MN.
Challenges (cont.) • OM and water availability • difficulty obtaining a representative N-rich strip! • Variability within field/catena • Other factors create differences in biomass • We assume N is the limiting factor • OM, soil moisture, S, etc. • Economics • Equipment, fertilizer, time
Opportunities • A diagnostic tool to reduce N applc’n rates • limited value if using Univ. rate rec’s • A diagnostic tool to adjust N rates (manure) • may be most successful in highly variable fields • requires an intense spatial data base over multiple years • Combine yields, soil OM, soil tests, drainage, slope, RS data, daily weather data, planting date, etc. • develop an Adaptive Management Strategy
Thanks Questions?