1 / 12

Virginia Polytechnic Institute and State University

Bojac 1A. Wickham 4A. Wickham 3A. Bojac 2A. Methods to Improve N Fertilization in Virginia. Virginia Polytechnic Institute and State University. Spatial Variability in Soils. Yield ranged from 218 to 9,598 lb/acre at a resolution < 9 ft 2. Estimate tiller density at GS 25.

harmon
Download Presentation

Virginia Polytechnic Institute and State University

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Bojac 1A Wickham 4A Wickham 3A Bojac 2A Methods to Improve N Fertilization in Virginia Virginia Polytechnic Institute and State University

  2. Spatial Variability in Soils Yield ranged from 218 to 9,598 lb/acre at a resolution < 9 ft2

  3. Estimate tiller density at GS 25 Willing to split spring N applications? YES YES Tiller density < 100 tillers ft-2? Obtain tissue test at GS 30 Apply N as recommended at GS 30 Apply N as recommended at GS 25 Virginia Sensor-Based Research • Site-specific, split-spring fertilization strategy • Can GS25 tiller counts and GS30 tissue testing be accomplished indirectly using sensor-based spectral measurements collected at a sub-meter resolution?

  4. Warsaw New Kent (7) Painter (13) Culpeper Port Royal Stuarts Draft Chatham Suffolk (8) EXPERIMENTAL SITES 1999-2003

  5. New Kent 2000 Painter-TS 2000 0.9 Port Royal 2000 0.8 Suffolk-TS 2000 Warsaw 2000 0.7 Chatham 2001 0.6 Culpeper 2001 NDVI 0.5 Painter 2001 Painter-AR 2001 0.4 y = 0.22 + 0.00045x (x<joint) y = 0.75 (x>joint) joint = 116 r2 = .78 Painter 2000 0.3 Painter-TD 2001 Painter-TS 2001 0.2 Painter-WR 2001 0.1 Stuarts Draft 2001 0 Suffolk 2001 0 50 100 150 200 Tiller Density, tillers ft-2 NDVI vs TILLER DENSITY

  6. INSEY vs. YIELD 8 Virginia; 8 site years y = 0.5415e367.45x r2 = 0.53 7 Oklahoma; 16 site years 6 y = 0.74076 + 0.1021e577.66x r2 = 0.64 5 Yield, Mg ha-1 4 3 2 1 0 0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 INSEY

  7. RESPONSE INDEX RI-NDVI = NDVIGS30 (Non-Limiting) / NDVIGS30 (Check) RI-Harvest = Yield (Non-Limiting) / Yield (Check)

  8. INSEY vs. YIELD 8 Virginia; 8 site years y = 0.5415e367.45x r2 = 0.53 7 Oklahoma; 16 site years 6 y = 0.74076 + 0.1021e577.66x r2 = 0.64 5 Yield, Mg ha-1 4 3 2 1 0 0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 INSEY

  9. N UPTAKE PATTERN

  10. RINDVI NDVIGS30 (0-N Check) NDVIGS30 (Non-Limiting) NDVIGS30 (Field) * RINDVI INSEY YPN Actual Yield YP0 * RINDVI NDVIGS30 * RINDVI Mg ha-1 4.24 2.88 3.96 r2 0.41 0.42 RESPONSE INDEX - VA • Instead of using RINDVI to adjust YP0 to YPN, adjust NDVIGS30 and go directly to YPN

  11. Actual Yield YP0 * RINDVI NDVIGS30 * RINDVI NDVIGS30 * (RI+ΔNDVI) Mg ha-1 4.24 2.88 3.96 4.40 r2 0.41 0.42 0.61 RESPONSE INDEX - VA INSEY = {NDVIGS30 * [RINDVI + ΔNDVI]} / DAP

  12. Virginia Research Results N Rate Method Yield 0 Check 45 100 Fixed 80 40-60 Standard 84 40-50 Sensor 91 7 bu/ac Increase 10 lb N/ac Decrease • NUE = 61%

More Related