1. The importance of computing Length of Growing Periods (LGP) in a
given locality to investigate the extent of climate change and to
design appropriate decision support systems and strategies
accordingly
By
Almaz Demessie
Agro meteorologist (MSc in Tropical Agricultural Development)
Meteorological Research and Study Team Leader
National Meteorological Agency of Ethiopia
International Workshop on Content, Communication and Use of Agro meteorological Products and Services for Sustainable Agriculture,
Toowoomba, Australia, 18‐21 May 2009

2. Outline of the topic
‐ Introduction
‐Discussion
‐Possible Adaptation Measures
‐Conclusion

3. Introduction
• The vulnerability and risk of crop production
due to weather fluctuations and climate
variability minimized by defining and
understanding the mean onset of rainfall to
start sowing and the time of cessation to
determine Length of Growing Period (LGP),
thereby choosing appropriate type and variety
of food as well as forage crops for livestock
feed.

4. Introduction…Contd
• LGP is describing the period during which crop
growth is not affected by climatic constraints,
i.e. the period of the year when water
availability allows crop growth and when the
temperature is not limiting crop growth.

5. Introduction…Contd
• As many studies have indicated, the duration
of the period in which rainfall exceeds selected
levels of evapotranspiration is the most useful
index of agricultural potential. This period
refers to the length of time during which water
and temperature permit crop growth.

6. Introduction
• Fears have arisen that; climate may be
changing for the worse and its impact on
agricultural production, which will reduce
the supply of food to the growing
population, especially in developing
countries.

7. Introduction…Contd
• As Wlhite, (cited in Climate Variability
and Agriculture by Y.P Abrol, S. Gadgil
and G. B.Pant 1996) pointed out, rain fed
agriculture in the semi‐arid tropics
limited mostly by high climatic variability
with principal limiting factor being
rainfall.

8. Introduction…Contd
• As Biswas, (cited in Climate Variability and
Agriculture by Y.P Abrol, S. Gadgil and G.
B.Pant 1996) has stated in most cases,
some deviation of average values between
two reference periods is mainly due to
large weather variability.

9. Introduction…Contd
• There may be real shifts of the average
or changes in variability between two
periods. These deviations from the
mean value constitute climate variation
or change.

10. Introduction…Contd
• Adverse climatic conditions are the
bottleneck of Ethiopia’s rain fed
agriculture development. As a result,
particularly in drought prone regions of
Ethiopia agriculture production is
determined by climate variability.

11. Introduction…Contd
• Many research studies have stated that
meteorological parameters like rainfall,
temperature and wind play an important role
in changing agricultural production more than
other parameters. Any deviation from the
mean climatic condition would affect
agricultural activities negatively.

12. Introduction…Contd
• Scientists and farmers should do together
for further understanding of crop–climate
relationships and formulate viable, locally
adapted production technologies that will
address critical issues such as climate
change.

13. Introduction…Contd
• Analyzing the trend of long‐term average of
different meteorological parameters is useful
to investigate the extent of climate change in a
given area. Among the indicative parameters,
computing Length of Growing Period (LGP) of
two different periods in a given locality is
important tool to observe the extent of climate
change in terms of moisture availability during
the growing season. Besides, it is very
important to design appropriate decision
support systems and strategies accordingly.

14. Discussion
The importance of computing Length of
Growing Periods (LGP) in a given locality
to investigate the extent of climate
change and to design appropriate
decision support systems and strategies
accordingly

15. Discussion … Contd
• As indicated in the above introductory
remarks meteorological parameters
like rainfall, temperature and wind
play an important role in changing
agricultural production more than
other parameters.

16. Discussion … Contd
• Any deviation from the mean climatic condition
would affect agricultural activities negatively.
Agriculture can show little sensitivity to moderate
variations around those means. If the condition
persisted a bit longer it could affect the overall
physiological activities of the plants and result in
crop damage and final yield reduction.

17. Discussion … Contd

18. Discussion … Contd

19. Discussion … Contd

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25. Discussion … Contd

26. Discussion … Contd

27. Discussion … Contd

28. Discussion … Contd

29. Possible Adaptation Measures
As indicted in the above discussion, we have observed
changes in LHP and LGP in different ways i.e. in some areas
like Jijiga (eastern) and Neghele (southern) there is a
decreasing trend. On the other hand, some areas like
Michewu (Northern) and Bahir Dar (northwestern) showed
increasing trend and there is no significant change in some
areas like Kulumsa (central), Fitche (central), Bedele
(southwestern) and Combolcha (northeastern) in terms of
LHP and LGP. Thus, the coping mechanisms are varying
from place to place accordingly.

30. Possible Adaptation … Contd
• Applying improved knowledge to develop better
techniques to resist the effect of climate change
in a given locality.
• Cultural practices that can precondition for the
plant need to be further explored and
implemented to mitigate the effect of stress
factors and excess moisture as well.

31. Possible Adaptation … Contd
• Change in land use by using deferent techniques
such as changing farm area, change to crops with
higher thermal requirements and drought‐
tolerant crop, a switch to crops with lower
moisture requirements and changes in crop
location.
• Change in management in terms of the use of
irrigation, fertilizer, in the control of pests, in soil
drainage, in farm infrastructure.

32. Possible Adaptation … Contd
• Create awareness among people about the
causes of climate changes so that farmers could
change their wrong management practices such
as deforestation, over grazing, etc. which are the
main causes for desertification and climate
change at large.

33. Possible Adaptation … Contd
• In some regions, it may be appropriate to take
a second look at traditional technologies and
crops as ways of coping with climate change.
• Better management techniques in food and
forage crops production should be developed
in order to mitigate the effect of climate
change.

34. Conclusion
• Analyzing of Length of Growing Period (LGP) of
two different periods (30 years and above in
each cases) in a given locality is one of the
important tools, to investigate the extent of
climate change in terms of moisture availability
in the process of food and forage crops
production. Moreover, it would be useful to
design appropriate decision support systems
and strategies accordingly.

35. THANK YOU