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

2. Resolution of Soil Fertility Variables
Organic Matter Range:

3. 1 Acre Grid, 16 Acres
490ft2
43560ft2
= 0.01
x x x x

4. Forage yield NDVI MehlichIII P70 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
Distance, ft
Distance, ft
Distance, ft

5. 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

6. 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

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

8. 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

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

10. 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)

11. x x x x

12. 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

13. National Geographic 1996
Southern Russia

14. Oklahoma

15. Oklahoma

16. Oklahoma

20. England

21. 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

22. 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

23. 120’ 130’ 1.33 PNSI 1.12 0N,0P 100N, 120P Hasil Sembiring
OSU Soil Fertility

24. N Fertilization Rate, lb/ac
Distance, ft 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

25. 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

26. 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