Oklahoma State University SOIL 4213 BIOEN 4213 Grid Sampling, and the Future of Soil Sampling Oklahoma State University

1 Acre Grid, 16 Acres 490ft2 43560ft2 = 0.01 x x x x

Forage yield NDVI MehlichIII P 70 60 50 40 30 20 10 70 60 50 40 30 20 10 70 60 50 40 30 20 10 lb/ac 8400 7200 6000 4800 3600 2400 1200 ppm 56 49 42 35 28 21 14 7 0.84 0.78 0.72 0.66 0.60 0.54 0.48 0.42 0.36 0.30 Distance, ft Distance, ft Distance, ft 1 3 5 7 1 3 5 7 1 3 5 7 Distance, ft Distance, ft Distance, ft

SOIL SAMPLING…. RESOLUTION? Grid: 1 acre, 43560ft2 (1) 1 Yield Monitor: 900 ft2 (0.02) x48 Resolution Study: 490ft2 (0.01) x89 OSU-VRT: 10ft2 (0.0002) x4356

x 4840 160 acre field ($10/soil sample) Sensor Based Map Based 1 Acre 43560 ft2 900 ft2 9 ft2 48.4 100 x 4840 Grid Based $1600 Map Based $77,440 Sensor Based $7,744,000 160 acre field ($10/soil sample) 1 Acre

Mean surface soil test P and fertilizer P recommendations, bemudagrass pasture, Burneyville, OK 70 30 Mehlich III 60 P Fertilizer 25 50 20 P FERTILIZER, kg/ha MEHLICH III P, mg/kg 40 15 30 10 20 5 10 2 4 6 8 10 12 14 16 18 20 22 DISTANCE, m

Mean surface soil test NH4-N + NO3-N and fertilizer N recommendations, bemudagrass pasture, Burneyville, OK 30 140 25 120 20 100 NH4-N + NO3-N, mg/kg N FERTILIZER, kg/ha 80 15 60 10 40 5 NH4-N + NO3-N 20 N Fertilizer 2 4 6 8 10 12 14 16 18 20 22 DISTANCE, m

‘Precision agriculture’ and ‘variable rate’ technologies must operate at the resolution where real differences are encountered in the field. OSU Team VRT

http://www.cropquest.com TEMPORAL VARIABILITY (South Carolina) Management Zones (PIONEER), Tom Doerge GRID SOIL SAMPLING (SOIL DOCTOR) last graph = every 6 square feet Soil Sampling as a Basis for Fertilizer Application, NDSU, Dave Franzen Systematic Evaluation of Precision Farming Soil Sampling Requirements, USDA-ARS, South Dakota Soil Sampling Strategies for Site Specific Management, Manitoba, CANADA (go to definition of Grid Soil Sampling) University of Georgia (NESPAL) http://www.cropquest.com

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Class Presentations (turn in title by February 23) Netscape Navigator (hyperlinks are dead) Make – up lecture……. 005 Computer Lab, Will Answer questions 2:30-3:20 Spatial Variability

National Geographic 1996 Southern Russia

Oklahoma

Oklahoma

Oklahoma

England

Bermudagrass, Burneyville, OK Prefertilization May 28 FR1 FR1 C1 VR1 VR2 C2 FR2 FR2 5 10 15 20 25 30 35 40 45 Bermudagrass, Burneyville, OK Prefertilization May 28 Distance, m 5 10 15 20 25 30 35 40 Distance, m

following fertilization FR1 FR1 C1 VR1 VR2 C2 FR2 FR2 5 10 15 20 25 30 35 40 45 Bermudagrass, Burneyville, OK First harvest following fertilization June 27 Distance, m 5 10 15 20 25 30 35 40 Distance, m

120’ 130’ 1.33 PNSI 1.12 0N,0P 100N, 120P Hasil Sembiring OSU Soil Fertility

N Fertilization Rate, lb/ac 0 10 20 30 40 50 60 70 80 90 100 Distance, ft 25 50 75 100 125 150 175 200 225 250 4 14 24 34 44 54 64 Variable N Rate: 36.3 lb N/ac Fixed N Rate: 80.0 lb N/ac 43.7 lb N/ac

Resolution of Soil Fertility Variables Organic Matter Range:1.6-3.5