Western crop science society of america conference oregon, 2013 - greenseeker-pocket sensor

• 1. Western Crop Science of America Conference June 10-13, 2013 Pendleton, OR Olga Walsh Assistant Professor, Soil Nutrient Management Western Triangle Agricultural Research Center Montana State University Evaluation of Sensor-Based Technologies and N Sources for Spring Wheat

2. Cooperators Mr. Robin Christiaens, Research Asossiate, WTARC, Conrad, MT Dr. Mal Westcott, Professor and Supt., WARC, Corvallis, MT Ms. Martha Knox, Research Specialist, WARC, Corvallis, MT Lindsey Martin, Producer, Pendroy, Teton County, MT 3. Objective To evaluate two sensors (GreenSeeker, and Pocket Sensor) for developing NDVI-based topdress fertilizer N recommendations in spring wheat in Montana To determine whether sensor-based recommendations have to be adjusted depending on what N fertilizer source (liquid UAN, or granular urea) is used 4. Materials and Methods 3 experimental sites: 2 dryland (WTARC, and on-farm study (Lindsey Martin, Pendroy, Teton County), and 1 irrigated (WARC) Choteau spring wheat variety Comprehensive soil sampling - preplant fertilizer application rates for all nutrients except N Plot size: 5x 25. 5. Materials and Methods 4 replications 4 preplant N rates (20, 40, 60, and 80 lbs N ac) 2 topdress N fertilizer sources (granual urea, 46-0-0, and liquid urea ammonium nitrate (UAN), 28-0-0) Topdress N fertilizer rate determined using NDVI obtained using GreenSeeker and Pocket Sensor at Feekes 5 growth stage 6. Treatment Preplant N Fertilizer Rate, lb N ac Topdress N Fertilizer Source 1 0 - 2 220 urea 3 20 urea 4 40 urea 5 60 urea 6 80 urea 7 20 UAN 8 40 UAN 9 60 UAN 10 80 UAN Treatment Structure 7. GreenSeeker Real-time active light source sensor Emits light at 670nm (red) and 780nm (NIR) Measures crop canopy reflectance at 200 readings /sec Outputs Normalized Difference Vegetative Index (NDVI) Equivalent to a plant physical examination NDVI is correlated with: Plant biomass Plant chlorophyll Crop yield Water stress Plant diseases, and Insect damage 8. Pocket Sensor Real-time active light source sensor Pre-calibrated to GreenSeeker Can be calibrated to any NDVI sensor NDVI can be directly compared independent of what sensor is used to sense the crop Cost ~ 25% of GreenSeeker cost No storage capability 2010 2012 9. Concept Summary 1. How much biomass is produced ? 2. What Yield is attainable without addition of N? 3. How responsive is the crop to N? 4. What Yield is attainable with addition of N? YPN = INSEY*RI NDVI = (NIR-red)/(NIR+red) INSEY = NDVI/GDD>0 RI = NDVI (NRS) /NDVI (FP) 10. Yield Trt Preplant N Fertilizer Rate, lb N ac-1 Topdress N Fertilizer Source Mean spring wheat grain yield, lb ac-1 2011 2012 WTARC WARC WTARC WARC Martin 1 0 - 829 (f) 1822 (e) 4229 (d) 3512 (f) 1698 (c) 2 220 urea 2378 (a) 3335 (abc) 4433 (d) 4981 (e) 1837 (bc) 3 20 urea 1369 (e) 2488 (d) 4797 (c) 5121 (de) 1995 (ab) 4 40 urea 1388 (e) 3061 (bc) 5178 (a) 5299 (bcde) 1996 (ab) 5 60 urea 1662 (cd) 3453 (ab) 5140 (abc) 5746 (abc) 2072 (ab) 6 80 urea 1925 (b) 3558 (a) 5262 (a) 5273 (cde) 2115 (a) 7 20 UAN 1298 (e) 2907 (cd) 4824 (bc) 5563 (abcd) 1997 (ab) 8 40 UAN 1465 (de) 3136 (abc) 4958 (abc) 5674 (abcd) 2065 (ab) 9 60 UAN 1771 (bc) 3004 (bc) 4951 (abc) 5862 (ab) 1980 (ab) 10 80 UAN 1935 (b) 3210 (abc) 5160 (ab) 5871 (a) 2027 (ab) Preplant fertilizer N was applied as urea. ** Topdress fertilizer N rates for Treatments 3-10 were determined based on the NDVI values obtained using GreenSeeker. The means in the same column followed by the same letter are not significantly different, p