1. Use of aerial imagery to detect N response in corn following alfalfa FR 5262 Matt Yost Stephen Palka

2. http://www.rothamsted.ac.uk Alfalfa provides N to following crops ~100 lb N ac -1 yr -1 2% N ~200 lb N ac -1 yr -1 http://www1.umn.edu/news

3. Alfalfa provides Nitrogen to corn for 2 years State 1 st -year N credit † 2 nd -year N credit † -------- lb N ac -1 -------- IA170140 IL10030 IN140--- KS120--- MI140--- MN15075 MO100--- ND15075 NE150--- OH140--- SD15075 WI15050

4. 42 on-farm alfalfa-corn N rate trials (2009-2012) K Regrowth, tillage time No-till Manure Predictors Stover removal, predictors 1 st -year corn 31 site-years 2 nd -year corn 11 site-years

5. More trials needed: Can yield differences be detected with NDVI?

6. 1 st year corn - ROHE Fall applied manure 4 fertilizer N rates Corn 2011

7. 2 nd year corn – MARPE

8. Aerial imagery: - 1m spatial resolution - 4 bands (RGB, NIR) - collected Aug. 2011 Create shapefiles of plots in ArcMap: GPS points (10-70 cm accuracy) Projected to NAD 83 UTM Zone 15N Change image band order: Originally IR R G B, changed to B G R IR in ArcMap Calculate vegetation Indices: Create AOI for plots Use signature editor to average pixel values for plots. Methods

9. ROHE MARPE Aerial images

10. Shapefiles of plots with -1.5 ft buffer

11. NDVI - MARPE

12. NDVI - ROHE

13. Methods of NDVI calculation

14. NDVI related to corn grain yield

15. Other indices were not better – IR/RED

16. Other indices were not better - TNDVI

17. Highest correlation – Silage yield vs. IR/Red

18. Can NDVI be used to detect corn yield differences? Main effectP values (P > F) Grain yieldSilage yieldNDVI Manure0.4840.1640.326 N0.0030.0250.042 Manure*N0.5150.3390.952 Regrowth0.177-0.656 N0.021-0.018 Regrowth*N0.234-0.835 YES!

19. Are the slopes of yield and NDVI related? - ROHE

20. Are the slopes of yield and NDVI related? - MARPE

21. Conclusions Farmers could use aerial imagery to determine whether N fertilizer treatments affected corn yield. This would make it easy for farmers to conduct their own research. More fields and correlations are needed to validate this conclusion. Future work: More fields, larger plots, Tassel cap transformations, online tools