1. TECHNICAL MEETING ON THE USE OF GPS IN THE AGRICULTURAL SURVEYS IN AFRICA, 27-28 November 2008 1 West Shoa area frame project – experiences in using of the GPS technology for area estimation Experiences in using of the GNSS technology in agriculture in Europe

2. TECHNICAL MEETING ON THE USE OF GPS IN THE AGRICULTURAL SURVEYS IN AFRICA, 27-28 November 2008 2 In the presentation Agriculture Unit Area-based subsidy in Europe - numbers Why to test tools? Validation of the tools on example of Garmin GPS72 Conclusions

3. TECHNICAL MEETING ON THE USE OF GPS IN THE AGRICULTURAL SURVEYS IN AFRICA, 27-28 November 2008 3 MARS-PAC (GeoCap) → Direct Payments to Farmers Agri4Cast ↓ Crop Yield Forecasting for EU FOODSEC ↓ Crop monitoring outside EU Who we are?

4. TECHNICAL MEETING ON THE USE OF GPS IN THE AGRICULTURAL SURVEYS IN AFRICA, 27-28 November 2008 4 Area-based subsidy controls in 2008 8.6 Million applications for 155 Million ha in 27 MS area of ~12.8 Million hectares controlled/measured 8.1 Million hectares measured on the satellite images (CwRS) 4.7 Million hectares measured in the field using GPS receivers, tapes and other tools GeoCAP (MARS PAC): Compliance and Control of Area-based subsidies in Agriculture and Regional Policies

5. TECHNICAL MEETING ON THE USE OF GPS IN THE AGRICULTURAL SURVEYS IN AFRICA, 27-28 November 2008 5 Introduction: Area measurement validation scheme –Purpose of the scheme to define an approach for the validation of area measurement methods for agricultural parcels, mainly using (but not restricted to) GPS equipment. –Motivation The availability of relatively low-priced GPS tools However, both the EC and Member States need assurance that the tools on offer are able to perform to acceptable standards.

6. TECHNICAL MEETING ON THE USE OF GPS IN THE AGRICULTURAL SURVEYS IN AFRICA, 27-28 November 2008 6 Why validation? Assessment of precision of the tool (random error) Assessment of accuracy of the tool (a systematic error) Evaluation of the time effectiveness of the tool Feeling on a general performance of the tool (practical issues, batteries life etc.) Decision: is the tool suitable for the needs of the project?

7. TECHNICAL MEETING ON THE USE OF GPS IN THE AGRICULTURAL SURVEYS IN AFRICA, 27-28 November 2008 7 Assessment of precision and accuracy of Garmin 72. Test design West Shoa area frame project – experiences in using of the GPS technology for area estimation.

8. TECHNICAL MEETING ON THE USE OF GPS IN THE AGRICULTURAL SURVEYS IN AFRICA, 27-28 November 2008 8 With what we measured? Garmin GPS 72 GeoXT -Trimble

9. TECHNICAL MEETING ON THE USE OF GPS IN THE AGRICULTURAL SURVEYS IN AFRICA, 27-28 November 2008 9 Test site 6 fields – representation of the landscape (shape, size, obstructions of horizon (borders)) Forest on a slope ~0.10 ha Steep slope, border with a forest ~0.21 ha Flat ~0.04 ha Moderate slope ~0.15 ha Flat ~0.31 ha Flat ~0.57 ha

10. TECHNICAL MEETING ON THE USE OF GPS IN THE AGRICULTURAL SURVEYS IN AFRICA, 27-28 November 2008 10 Field A: ~0,31ha, flat

11. TECHNICAL MEETING ON THE USE OF GPS IN THE AGRICULTURAL SURVEYS IN AFRICA, 27-28 November 2008 11 Field B: ~0,04ha, flat

12. TECHNICAL MEETING ON THE USE OF GPS IN THE AGRICULTURAL SURVEYS IN AFRICA, 27-28 November 2008 12 Field C: ~0,15ha, moderate slope

13. TECHNICAL MEETING ON THE USE OF GPS IN THE AGRICULTURAL SURVEYS IN AFRICA, 27-28 November 2008 13 Field D: ~0,10ha, Forest on a slope

14. TECHNICAL MEETING ON THE USE OF GPS IN THE AGRICULTURAL SURVEYS IN AFRICA, 27-28 November 2008 14 Field E: ~0,21ha, steep slope, border with the forest

15. TECHNICAL MEETING ON THE USE OF GPS IN THE AGRICULTURAL SURVEYS IN AFRICA, 27-28 November 2008 15 Field F: ~0,57ha, flat

16. TECHNICAL MEETING ON THE USE OF GPS IN THE AGRICULTURAL SURVEYS IN AFRICA, 27-28 November 2008 16 Artificial borders clearly marked:

17. TECHNICAL MEETING ON THE USE OF GPS IN THE AGRICULTURAL SURVEYS IN AFRICA, 27-28 November 2008 17 How many times?: 5 runs with 4 repetitions = 20 measurements of one field with one receiver How to measure? When?: 1 run  4 measurements in row for a field = repeatability conditions (influence of the satellite system limited) runs should start at different time of the day = reproducibility conditions (influence of the satellite system taken into account)

18. TECHNICAL MEETING ON THE USE OF GPS IN THE AGRICULTURAL SURVEYS IN AFRICA, 27-28 November 2008 18 Practical issues: Within one run walk clockwise and anti-clockwise, Try to have one operator per field, Make the border of the field comfortable for walking, GPS receivers give the projected (horizontal) area, GPS area measurements are only comparable with rope & compass on flat fields!!!

19. TECHNICAL MEETING ON THE USE OF GPS IN THE AGRICULTURAL SURVEYS IN AFRICA, 27-28 November 2008 19 Statistics Reference area ( GeoXT with data post-processing ) Outliers detection (Grubbs’ and Cochran’s tests) Repeatability standard deviation Reproducibility standard deviation Bias of the measurements Additionally: ANOVA to analyze influence of factors like: operator, field, size, border type etc.

20. TECHNICAL MEETING ON THE USE OF GPS IN THE AGRICULTURAL SURVEYS IN AFRICA, 27-28 November 2008 20 Assessment of precision and accuracy of Garmin GPS72

21. TECHNICAL MEETING ON THE USE OF GPS IN THE AGRICULTURAL SURVEYS IN AFRICA, 27-28 November 2008 21 Conclusions: The CSA have capacity to design and run validation tests of the GNSS receivers, Garmin GPS72 is a user-friendly tool, easy to handle even for absolute beginners, Garmin GPS 72 seems not to give any significant systematic error with random errors (1σ) below 3.4% for fields >0.2ha, Time-efficiency has been proven during the tests (up to 20 fields per hour)

22. TECHNICAL MEETING ON THE USE OF GPS IN THE AGRICULTURAL SURVEYS IN AFRICA, 27-28 November 2008 22 Impact of usage of the projected area instead of the sloped should be analyzed, Storing results of the measurements in a database could benefit and support spatial and temporal analysis of the data Other GNSS receivers owned by the CSA should be tested before using them for area measurements. Conclusions:

23. TECHNICAL MEETING ON THE USE OF GPS IN THE AGRICULTURAL SURVEYS IN AFRICA, 27-28 November 2008 23 Thank you for your attention!