TECHNICAL METING ON THE USE OF GPS FOR CROP AREA MEASUREMENT IN THE AGRICULTURAL SURVEYS IN AFRICA USE OF GPS FOR CROP AREA MEASUREMENT : FIELD EXPERIENCE IN NIGER ( WEST AFRICA) Addis-ABABA, Ethiopia: November 2008 By Amadou BOUREIMA

ABSTRACT I. INTRODUCTION FIELD EXPERIENCE II. FIELD EXPERIENCE 1. Agro-Ecologique Zones of study 1. Agro-Ecologique Zones of study 2. Field team and duration of the experience 2. Field team and duration of the experience 3. Materiels used and questionnaires 3. Materiels used and questionnaires 4. Methodological approach 4. Methodological approach 5. Outcomes/ Results 5. Outcomes/ Results 6.Constraints and difficulties 6.Constraints and difficulties 7. Lessons drawn 7. Lessons drawn III. Conclusion and main recommendation

 Niger is located in West Africa : 11°40 and 23°30 N and 0°10 and 16° E with a total area of km²;  Population is estimated at 13 million with a demographic growth rate of 3,3%;  The economy depends essentially on uranium, the agricultural produce and Breeding;  The majority of the production is carried out by family exploitations of small sizes, turned towards the autosubsistance and whose techniques of production remain traditional;  The cultivable areas represent 12 % of the total land surface and the agricultural outputs depend primarily on the rainfall. INTRODUCTION

Suite  This work followed upon a need expressed by FAO to test the evaluation of the areas of cultures (plots) by the use of GPS which before was done with hand Compass.  It is within this framework that the RGAC ( Recensement General de l’Agriculture et du Cheptel ) project whose essential aim is to update knowledge on agriculture and the breeding carried out in the end of 2005 in Niger to experiment plots surfaces evaluation by the methods of Compass and GPS.  Thus, the same national device of investigation and census of the RGAC was used on the field for the data collection.

2.1 Agro-Ecological zones of study  The tests was done in the eight regions of contry;  the results presented related for 4 regions (Diffa, Dosso Niamey and of Tillabéri);  The plots tests are precisely localised:  in the Systems of Komadougou (Diffa),  the plates of the west (Dosso),  the system dunaire of the west (Tillabéri);  and the valley of the river Niger (Niamey).

2.2 Field team and duration of the experience  TEAM  4 national supervisors (1 per area);  4 supervisors (1 per area);  4 controllers (1 per selected department)  8 investigators (including 2 per department).  DURATION: 21 DAYS  Choice of the owners and types of pieces 1 day ;  Development and test of the questionnaire: 3 days;  Formation of the implied agents: 2 days;  Data-gathering on the ground: 10 days;  Seizure and analyzes data: 3 days  Exit of the results and development report/ratio: 2 days

 Materials: GPS, compass, meter ribbon, stakes, support to be written ;  Logistics: Moto/véhicule 4x4 for displacement equips;  Questionnary: measurement of the surfaces of the plot 2.3 Materiels used and questionnaires

2.4. Methodological approach 1. Choice of the owners and types of plot ; 2. Development and test of the questionnaire ; 3. Formation of the agents ; 4. Data-gathering ; 5. Evaluation method of surfaces using the compass and the meter ribbon ; 6. Evaluation method of surfaces using a GPS by Navigation: For Garmin 12 XL ; 7. Method evaluation of the surfaces using a GPS by catching points (Latitude, Longitude) on the level of the angles: For Garmin 12 XL

2.5 Results  Basic type of data obtained (see doc) ;  Result of the comparative test for 59 plots using the three methods Methods Number of idem surface get with method Number of surface get with compass who were < Surface by navigation GPS Number of surface get by navigation GPS who were < surface get by Catch Points GPS Boussole/Navig ation GPS1/59 soit 1,69% 35/59 soit 59,32% - Boussole/Catch Point GPS2/59 soit 3,38% 35/59 soit 59,32% - Navigation GPS/Catch Points GPS11/59 soit 17% -27/59 soit 46 % NB: Realized under the same working conditions

2.5 Results (suite )

Comparative graph of saving of time of time between compass-GPS and 2 Method of GPS 2.5 Results (suite )

Comparison of the surfaces measured by 4 types of GPS

Magellan Explorist 400 Garmin 12 XL Garmin Venture Etrex Garmin Results (suite )

2.6 Constraints and difficulties  Availability of the farmer ;  Difficult access to certain pieces enclosed with thorn-bushes or flooded ;  Dependence of the daily schedule of work of the farmers concerned ;  Miss recycling of the collecting agents ;  Knowledge of data processing and the statistical concepts.

2.7 Lessons drawn Advantages:  Saving of time compared to the traditional compass method (realization of the area of 4 times a plot of approximately 3 hectares with the GPS),  Direct reading of the surfaces and visual form of the plots with GPS,  Precision;  Less people is use on the field with the GPS,  Method GPS can be made with foot, with motor bike, by bicycle or any other vehicle,  gaining of other types of data (Lat/long, altitude etc); Usable what so ever the vegetative stage of the cultures ;  High sensibility of Magellan Explorist 400 to evaluate important superficies

2.7 Lessons drawn (Suite) Limits GPS:  Cost is relatively higher than the compass;  Require more formation ; Compass:  Parcelling out of the large areas into smaller areas to determine the total surface (more error of precision);  Slowness;  Less precise,  Can be use difficulty when cereals crops is at a higher stage and close to maturation (millet and sorghum),  Require another equipment for the calculation,  Require a batch of material (Meter ribbon, Jalon.....) and labour. Operator (Investigating)  Risk duplication of the surfaces if the operator forgets to remove the values of the preceding pieces;  Difficulty of evaluation to foot of the large surfaces;  Problem of comprehension of the language of the farmer

In conclusion it is necessary to retain the following points following this experiment test:  To have a method of more effective measurement of plot which is that of the GPS;  Saving of time compared with the traditional method (method compass);  Better method evaluation of the surfaces;  Possibility of extension of methodology GPS on the pastorales enclaves which formerly are not taken into account in the evaluation of the assessment forages;  Economic, less tiresome and replicable. III. Conclusion and main recommendation

III. Main recommendation In recommendation, it is necessary:  Need for extension and validation of methodology GPS;  Need for generalization on the level of the other sectors;  Need for regular recycling of the agents;  Need for informing in time the farmers on the work schedule;  Use of the motor bikes for the large surfaces;  Experience sharing with the other countries.

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