Sensor Based Fertilizer Nitrogen Management Jac J. Varco Dept. of Plant and Soil Sciences Mississippi State University
Nitrogen in Cotton Production Increased costs linked to energy costs Deficiency limits yield and lowers quality Excess rank growth, hbll boll rot, difficulty in harvesting, and increased need for growth regulators, insecticides, and defoliants
N availability is a determinant of Biomass Leaf area Greenness Physiological processes Yield
Theoretical Basis for Using Crop Reflectance Crop pgrowth is a result of an integration of all factors influencing growth including the size of the available soil N pool, available water, and climatic conditions Remote sensing/crop reflectance is an indication of growth Selected crop reflectance indices can be used as surrogate measurements e e for leaf N and N content t Spatial variances in crop reflectance are an indication of growth potential and at least a partial indication of the relative differences in the utilization i of and/or size of the available soil N pool
Crop Reflectance Based Fertilizer N Management What we know: Green band indices-effective for determining N status cotton (Buscalia and Varco, 2002;Peterson, 2002; Bronson et al., 2003) Leaf N and K concentrations can be predicted utilizing crop reflectance, especially in green and red edge spectral regions (Fridgen and Varco, 2004) Vegetative indices from aerial imagery most highly correlated with leaf N at peak bloom (Emerine, 2004) Structural indices (e.g. NDVI, SAVI etc.) related to canopy scattering and growth are better indicators of field variability at earlier growth stages, while chlorophyll related indices are better related at later stages (e.g. Green Index or GI) (Zarco-Tejada et al., 2005)
Use of Crop Sensors for Growth and N Detection REFLECTAN ANCE, % 70 60 50 40 30 20 10 2009 EARLY FLOWER 0 lb N/Acre 40 lb N/Acre 80 lb N/Acre 120 lb N/Acre GreenSeeker Crop Circle YARA N Sensor Representative crop reflectance in visible to NIR Wavelengths used by different sensors indicated in color Representative cotton canopy reflectance by N rate 0 400 500 600 700 800 900 WAVELENGTH, nm
Greenseeker 650 nm 770 nm Crop Circle 650 nm 880 nm YARA N Sensor five user selected 20 research mode YARA ALS 730 nm 760 nm Topcon Cropscan 735 nm and 808 nm calibrated to YARA ALS
RE EFLECTANC CE, % 60 0 lb N/Acre 40 lb N/Acre 80 lb N/Acre 120 lb N/Acre YARA N Sensor 40 20 2009 EARLY FLOWER YARA N Sensor Cotton Canopy Scan Wavelengths collected in research mode shown in blue 0 400 500 600 700 800 900 WAVELENGTH, nm
METHODS Plant Science Research Unit, Mississippi State, MS Randomized complete block design 4 Fertilizer N rates w/4 Reps 12 rows wide @ 38 row spacing 125 long 4 sub-locations for sampling
Treatments METHODS (CONT.) 04080and120lbN/acre 0, 40, 80, Planting (50%) Early square (50%) Cultural practices No-till/CT on beds DPL BG/RR 445, 2010 DPL 1028 No growth regulator applied Weed and insect control according to recommendations dti
Aug. 4, 2010 Late Flowering
Crop Response to Fertilizer N UAN 32%, 50% after planting 50% @ early square, 8-9 to one side of row, 3 deep Lint Yi ield, lb/acre 2000 1800 1600 1400 1200 1000 800 600 400 200 Yearly NT/CT Cotton Yield, Miss. State 2004 2005 2006 2007 2008 2009 2010 0 40 80 120 Fertilizer N Rate, lb/acre 1200 Average Yield Mississippi State 2004-2010 Lint Yield, lb/acre 1100 1000 900 800 R 2 =0.996 700 0 40 80 120 Fertilizer N Rate, lb/acre
0.52 2008 EARLY SQUARE 0.60 2009 EARLY SQUARE 050 0.50 0.48 0.55 NDVI 0.46 044 0.44 0.42 0.40 r ²=0.85 r ²=0.44 r ²=0.93 Crop Circle GreenSeeker YARA N Sensor 038 0.38 3.6 3.8 4.0 4.2 4.4 4.6 LEAF N, % NDVI 0.50 0.45 r ²=0.98 r ²=0.98 0.40 r ²=0.99 Crop Circle GreenSeeker YARA N Sensor 035 0.35 3.2 3.4 3.6 3.8 4.0 4.2 4.4 LEAF N, %
2008 EARLY FLOWER 2009 EARLY FLOWER 0.90 0.90 0.88 0.86 0.84 0.82 r ²=0.99 0.88 0.86 0.84 r ²=0.97 r ²=0.98 NDVI 0.80 0.78 r ²=0.94 NDVI 0.82 0.76 0.80 0.74 0.72 0.70 0.68 r ²=0.97 Crop Circle GreenSeeker YARA N Sensor 2.6 2.8 3.0 3.2 3.4 3.6 3.8 0.74 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.0 4.1 LEAF N, % LEAF N, % 0.78 0.76 r ²=0.98 Crop Circle GreenSeeker YARA N Sensor
2008 EARLY SQUARE 2008 EARLY FLOWER 0.54 0.80 0.52 r ²=0.61 078 0.78 r ²=0.83 0.50 0.76 GNDVI 0.48 046 0.46 GNDVI 0.74 0.44 0.72 0.42 0.70 040 0.40 068 0.68 14 16 18 20 22 24 26 28 50 55 60 65 70 75 80 85 90 PLANT HEIGHT, cm PLANT HEIGHT, cm 2008 PEAK FLOWER 0.80 0.78 r ²=0.78 GNDV VI 0.76 0.74 0.72 0.70 60 70 80 90 PLANT HEIGHT, cm
0.80 Mississippi State 0.75 0.70 GNDV VI 0.65 0.60 0.55 0.50 0.45 6/11/08 6/19/08 6/25/08 7/2/08 7/9/08 0.40 2.5 3.0 3.5 4.0 4.5 5.0 Leaf N, %
2008 SEASON N UPTAKE, lbs N/AC CRE TO OTAL N UPTAKE 140 120 100 80 60 40 0 20 40 60 80 100 120 140 FERTILIZER RATE, lbs N/ACRE
0.84 0.82 r ²=0.86 2008/2009 PEAK FLOWERING 080 0.80 GN NDVI 0.78 0.76 0.74 0.72 0.70 0.68 2.5 3.0 3.5 4.0 4.5 LEAF N, %
Predicted Leaf N Map @ Peak Flowering 7/21/2004 8/04/2005 Leaf N nsense_boundary Prediction Map [72104dat.csv].[PreLeafN] Filled Contours 1.94371402-2.37742186 2.37742186-2.71331644 2.71331644-3.14702439 3.14702439-3.70702887 3.70702887-4.43010855 Leaf N Prediction Map [050804dat.csv].[PreLeafN] Filled Contours 2.79583001-3.22551918 3.22551918-3.62861252 3.62861252-4.00675678 4.00675678-4.40985012 4.40985012-4.83953905 nsense_boundary
Predicted Plant Height 8/04/2005 Leaf N nsense_boundary Predicted N Biomass Index 8/04/2005 Leaf N nsense_boundary Prediction Map Prediction Map [050804dat.csv].[PrePH] [050804dat.csv].[PreLNPH] Filled Contours Filled Contours 77.2931671-88.5834122 241.405075-274.747162 88.5834122-98.2801208 274.747162-312.119659 98.2801208-106.6082 312.119659-354.009796 106 6082-113 106.6082 113.760834 760834 354.009796-400.963623 113.760834-119.903915 400.963623-453.593262 119.903915-125.179947 453.593262-512.584839 125.179947-129.711304 512.584839-578.707336 129.711304-134.987335 578.707336-652.822815
Cotton Leaf N Early Flowering 2002
Cotton Leaf N Early Flowering 2003
5.0 Mississippi State 4.5 Leaf N, % 4.0 3.5 30 3.0 0lbN/acre 40 lb N/acre 80 lb N/acre 2.5 120 lb N/acre 2.0 6/9/2008 6/16/2008 6/23/2008 6/30/2008 7/7/2008 7/14/2008 Date
0.80 Mississippi State 0.75 0.70 GNDV VI 0.65 0.60 0.55 0.50 0.45 6/11/08 6/19/08 6/25/08 7/2/08 7/9/08 0.40 2.5 3.0 3.5 4.0 4.5 5.0 Leaf N, %
On-The-Go Crop Reflectance YARA N Sensor Wavelength Channels: 20 user selectable Wavelength range: 450 to 900 nm, ± 5nm Optical inputs: 4 reflectance, 1 irradiance Acquisition interval: 1 second Area scanned: 50-100 m²/s Positioning Data: Trimble Pro XR Speed: 3.5 mph
Viewing i Geometry Positioning of optical inputs as viewed from overhead and from behind. Source: YARA (Hydro Agri), tec5hellma
Wavelengths - 550 (green), 650 (red), 700 (red edge), 710 (red edge), 840 (NIR) Currently also collecting 450, 500, 570, 600, 620, 640, 660, 670, 680, 720, 740, 760, 780, 800, and 850 Green Normalized Vegetation Index GNDVI = (NIR Green)/(NIR + Green) Normalized Vegetation Index NDVI= (NIR Red)/(NIR + red)
0.9 2008 2009 0.9 0.8 r ²=0.97 0.8 r ²=0.96 GNDVI 0.7 0.6 GNDVI 0.7 0.6 0.5 0.5 0.4 0.4 20 40 60 80 100 PLANT HEIGHT, cm 0.3 0 20 40 60 80 100 120 PLANT HEIGHT, cm
EARLY SQUARE 25 June 2009 2nd WEEK OF SQUARE 1 July 2009 710 713 712 WAVELENGTH, nm 708 706 704 r ²=0.864 WAVELENGTH, nm 711 710 709 708 r ²=0.695 702 707 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 LEAF N, % 715 3rd WEEK OF SQUARE 8 July 2009 706 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 LEAF N, % 714, nm WAVELENGTH 713 712 711 710 r ²=0.805 709 708 3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0 LEAF N, %
EARLY SQUARE 25 June 2009 EARLY SQUARE 25 June 2009 0.60 710 0.55 708 NDVI 0.50 0.45 r ²=0.650 LENGTH, nm 706 r ²=0.864 0.40 WAVE 704 0.35 702 030 0.30 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 LEAF N, % LEAF N, %
0.85 Mississippi State 2008 80 lb N/acre 0.80 0.75 r 2 =0.96 GN NDVI 0.70 0.65 0.60 0.55 0.50 0.45 6/9/2008 6/16/2008 6/23/2008 6/30/2008 7/7/2008 7/14/2008 Date
5.0 Mississippi State 4.5 R 2 =0.99 eaf N, % L 4.0 35 3.5 2 R 2 =0.99 3.0 Early Square ave. 04, 05, 07, 08 Early Bloom ave. 04, 05, 07, 08 2.5 0 40 80 120 Fertilizer N Rate, lb/acre
1. Apply initial fertilization @ a rate which will promote favorable growth say 40 lb N/acre. 2. Allow cotton growth to progress to point where spatial variability is evident and N related and backed up by some sampling and tissue analyses. 3. Decide on side dress N rate which in combination w/initial application is a good field average rate. This will require some experience w/the field and grower input. In this case let s use 40 lb N/acre for a total applied of 80 lb N/acre. 4. Use the sensor to collect readings to establish a two point or more calibration curve or use a robust algorithm. 5. On-the-sensing establishes fertilizer equivalency of the standing crop and N rate is adjusted accordingly.
2008-3rd Week Squaring Estimated Sidedress N Rate 140 lb/acre Fertilize er N Rate, 120 Sensor based fertilizer equivalency Target total N rate Fertilizer N application rate 100 80 60 40 20 0-20 0.62 0.64 0.66 0.68 0.70 0.72 GNDVI
On-the-go sensors can assist in the mapping of spatial and temporal variations in growth and N nutrition Real time crop reflectance can assist in the application of fertilizer N to account for spatial differences in N availability, but systematic calibration is necessary to maximize accuracy The profit maximizing fertilizer N rate should continue to be pursued as the desired target
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