Oklahoma State University February 2002 SOIL 4213 BIOEN 4213 Spatial Variability, What can we see? Oklahoma State University February 2002

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

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

Field Element Size Area which provides the most precise measure of the available nutrient where the level of that nutrient changes with distance

FES should theoretically identify 1. The smallest resolution where cause and effect relationships can be identified 2. The precise resolution where variances between paired samples of the same size (area) become unrelated and where heterogeneity can be recognized 3. The resolution where misapplication could pose a risk to the environment 4. The treated resolution where net economic return is achieved. 5. The resolution where differences in yield potential may exist

‘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

x x x x

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

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