Remote sensing –Beyond images Mexico 14-15 December 2013 The workshop was organized by CIMMYT Global Conservation Agriculture Program (GCAP) and funded by the Bill & Melinda Gates Foundation (BMGF), the Mexican Secretariat of Agriculture, Livestock, Rural Development, Fisheries and Food (SAGARPA), the International Maize and Wheat Improvement Center (CIMMYT), CGIAR Research Program on Maize, the Cereal System Initiative for South Asia (CSISA) and the Sustainable Modernization of the Traditional Agriculture (MasAgro)

1. AGRICULTURAL STATISTICS OF ROOTS AND TUBERS
PERCY ZOROGASTÚA C.
ROBERTO QUIROZ
MICHAEL POTTS
STEFFEN SCHULZ

2. INTRODUCTION
Potato crop has a production of more than 314000 MT/Y and is the fourth crop of
importance in the world. Sweet potato production reaches more than 110000
MT/year and occupies the seventh place in the world.
In recent years, CIP has introduced several clones of orange flesh sweet potato in
Africa, as a strategy to solve the severe vitamin A deficiency affecting the human
population. This introduction requires precise information on cropping area to
assess the potential dissemination of the new germplasm and their beneficiaries,
both in the spatial and time scales. This knowledge is necessary for estimating the
production, marketable volumes, per capita consumption, required inputs and to
orient research.
Potato is acquiring more importance in Ethiopia due to frequent adverse factors
that cause famine problems. Information about the area and zones where potato is
grown and production volumes are necessary, in order to provide agricultural
inputs for increasing productivity

3. There are reasons to believe that the statistics of FAO in Africa do not have a
relation to the actual cultivated area. This reasonable doubt is based on the fact
that crop statistics related to small producers, are obtained through field sampling
and survey techniques that have some limitations.
CIP’s Production Systems and the Environment Sub-Program is developing and
validating methodologies based on a) Spectroradiometry and the use of highresolution remote sensing images that provides reliable, accurate, and dynamic
information for estimating cropping areas and b) Detection of recently dehaulmed
potato areas

4. Key questions:
Actual
What is?
How much is there ?
Where do we have ?
What is the current status?
Potential
How much more it could produce?
Where else it could be?

5. Agricultural statistics can be determined under two criteria:
one through the use of a List frame in which a list of
production units that can be registered each one through a
census or only taken some samples of them, and through
the Area frame in which area of land cover & land use is
determined.
We have used the Area frame criteria, with the estimation of
the cropping area derived from remote sensing products
and field data, classifying high resolution satellite data and
counting pixels.
We utilized high resolution Spot images for building the
agricultural statistics for the districts of Kumi (sweetpotato)
in Uganda and Jeldu (potato) in Ethiopia

6. 50
Generic spectral signatures
30
20
Dry vegetation
10
Green vegetation
water
0
% Reflectance
40
Soil
B
G
500
R
NEAR IR
1000
MID INFRARED
1500
Wavelength in nanometers
2000
2500

7. IMAGE ANALYSIS
Source: National Technical University of Athens

8. Statistics of Sweetpotato in Kumi district, UGANDA
Kumi

10. Kumi climatic diagram
90
160
80
140
70
120
60
100
50
80
40
60
30
40
20
20
10
0
0
Jan
Feb
Mar May Apr
Jun
Jul
Aug Sep
Oct
Months
Pp
ET
T max
T min
Nov
Dic
Temperature (ºC )
100
180
Precipitation / ET (mm)
200

12. CROPS REFLECTANCES
1
0.9
Reflectance
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
300
400
500
600
700
800
900
1000
1100
1200
Wavelength
Maize
Bare Soil
Millet
Sweet potato
Cassava
Banana

13. Classified SPOT Image of the Kumi district, May 2006

14. Classified SPOT Image of the Kumi district, October 2006

15. Confusion Matrix of Land Cover & Land Use of Kumi (%)
Ground
Truth
Classificati
on
Category
1
2
3
4
5
6
7
1
2
3
Forest/Mango
Water bodies
Clouds
92.9
0
0
0
100
0
0
0
100
0.6
0
0
0
0
0
0
0
0
0
0
0
4
Sweetpotato
5.9
0
0
93.1
0
0
0
5
6
7
Grassland
Other crops
Bare soil
Total
0.6
0.6
0
100
0
0
0
100
0
0
0
100
0
6.4
0
100
100
0
0
100
17.4
82.5
0
100
0
0
100
100

16. Area covered by different land use and plant cover categories, May and October 2006
44620 ha of sweetpotato

17. Area planted in Kumi for Sweet potato
30,000
25,000
Ha.
20,000
15,000
10,000
5,000
0
1992
1993
1994
1995
1996
1997
Year
Source: Uganda Bureau of Statistics
1998
1999
2000
2001
2002
2,003
The area
projected to
2006
according to
official
statistical
records, compa
red with our
results was 63
% of the total
surface
covered by
sweetpotato

18. Potato in the
Jeldu
district, West
Shewa region –
Ethiopia
Jeldu
Addis Ababa
Source: Google Earth

19. Source: Gildemacher et al, 2009

20. Image SPOT 5 XS 10/11/2012
Source: Spot Image-Astrium

21. Land Cover & Land Use Dec. 2012 in Jeldu, West Shewa – Ethiopia
Category
Forest/Shrubs
Grassland/Weeds/Bare soil
Wheat
Barley
Teff
Potato
Urban Area / Infraestructure
Other crops
ND
Total
Area (Ha)
34635.9
16880.5
26284.1
14886.4
6210.6
10663.6
4098.6
13503.0
4078.0
131240.7
%
26.4
12.9
20.0
11.3
4.7
8.1
3.1
10.3
3.1
100.0
Source: CIP, based on: XS SPOT image

22. Confusion Matrix of Land Cover & Land Use of Jeldu District
Ground truth/
Classification
Potato
Grassland/Weeds
/Bare soil/Fallow
Forest
Wheat
Teff
Barley
Urban area/
Infrastructure
Total
Urban
area/
Potato Grassland Forest Wheat Teff Barley Infrastr.
93.5
0
0
0
0
0
11.3
6.3
0.0
0.0
0.0
0.2
78.6
0
0
21.4
0
0
100
0
0
0
0
0
70.8
0
29.2
0
0
0
0
2
0
0
1
0
99
7.2
0
0
0
0
0.0
100.0
0
100
0
100
0
100
0
0
1
100
81.4
100

23. Conclusions
The radiometric evaluation and processing of the SPOT scenes of
the district of Kumi in Uganda have made it possible to determine
that the sweet potato foliage has a distinct spectral pattern
defined by a low reflectance in the visible range of the spectrum
and a high reflectance in the near infrared range.
This spectral pattern makes it possible to identify the sweet
potato crop with a high degree of certainty, which allows defining
with precision the cultivated area and the spatial distribution of
the crop through the utilization of high-resolution SPOT images.

24. The results suggest that the traditional statistics of sweet
potato was underestimated by about 37 % of total area.
Jeldu district in Ethiopia has 131240.7 ha, where we
determined 10386.4 ha with potato (7.9 %) as to December
of 2012. Jeldu is dominated by cereals cropping which
occupy 36% of the total area. Forest area and scrubland
occupy the 26.4% of the total. Grasses, weeds and bare soils
occupy 13% of total. Urban area and infrastructure cover the
3.1% and 13.4% of total area were covered by other crops

25. Thank you very much for your attention
p.zorogastua@cgiar.org