Climate and Soils
Nyeri and Othaya
The towns of Nyeri and Othaya are both located in the District of Nyeri. They are about 150km
and 125 km north of Nairobi, respectively.
They are located between Mt. Kenya to the northeast and the Aberdare Range to the west.
(Upper Tana: Landforms and Rivers, 2000)
Climate
The District of Nyeri has 3,356 square km of land, with no significant bodies of water. It is
classified as cold to warm, wet and as a medium altitude region. The altitude ranges from 1500 –
2000 m, and annual rainfall is 1,200- 1,600 mm/year in four of five years (Kenya National
Bureau of Statistics).
(Agro-Climactic Zone Map of Kenya, 1980)
Nyeri falls into the classification of semi-humid while Othaya is considered sub-humid and
receives about 200mm more rain a year than Nyeri. Most of the vegetation in Nyeri includes dry
forests and moist woodlands and in Othaya the vegetation consists of moist and dry forests
(Agro-Climactic Zone Map of Kenya, 1980). In the district of Nyeri the land ranges from
footslopes to hills and mountain foot ridges (World Resources Institute, 2007). There are no
bodies of water in the district but streams do run from Mt. Kenya and the Aberdare range (Kenya
National Bureau of Statistics). Othaya’s average elevation, 1825m, is slightly above Nyeri,
1768m, but the two towns fall into the same temperature range (Falling Rain Genomics, 2010).
The mean annual temperature ranges from 16-18⁰C, the mean maximum temperature ranges
from 22-24⁰C, and the mean minimum temperature ranges from 10-12⁰C. Although the recorded
absolute minimum temperature ranges from 2-4⁰C some frosts have been recorded in Nyeri
(Agro-Climactic Zone Map of Kenya, 1980 and Orodho, 2001). The average daily humidity
ranges from 64% to 83% and the average wind speed ranges from 9 to 10kph (Weather2).
Elevation
FAO: 1996
(Elevation, 1996)
The average annual rainfall in the district of Nyeri ranges from 1200 to 1600mm (World
Resources Institute, 2007). The average annual potential evaporation in Nyeri and Othaya are
1450-2200mm and 1300-2100mm, respectively (Agro-Climactic Zone Map of Kenya, 1980).
Precipitation
FAO:
-Last updated in 2000
-averaged over 37
years
(Precipitation, 2000)
(Climate, mean monthly rainfall & humidity, 1961)
Kenyan agriculture is controlled by the wet and dry seasons and many problems come from the
unreliable rainfall. In one year there are two wet seasons. The long rain lasts from about middle
March to the end of May and the short rain usually lasts from October into December. During
those rainy seasons is when the crops are planted and grown. The rest of the year, during the dry
season, the crops are harvested and the land is prepared for another planting. Often the land
receives no resting period and the same crops are grown in the same fields time after time.
Average rainfall can vary and dry years bring devastation and hunger (Office of the Prime
Minister, 2008). The monthly rainfall averaged over a period of six years ending in 1961 for the
district of Nyeri is as follows:
Average Monthly Rainfall (mm)
Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
25
30
89
178 130
38
25
38
23
76
89
76
(Climate, mean monthly rainfall & humidity, 1961)
The average water availability in Kenya is only 985m3 per capita per year, compared to the
Unites State’s 10,837m3, which classifies Kenya as water scarce by the Kenya Atlas (Water
Resources, 2002 and World Resources Institute, 2007). Overall Nyeri has a medium to high
potential for plant growth with a 5-10% risk of failure of an adapted maize crop, and Othaya has
a high potential for plant growth with a 1-5% risk of failure for an adapted maize crop (AgroClimactic Zone Map of Kenya, 1980).
Info from maps in PSU Library
2001Elevation:
Nyeri Othaya
Nyeri
Othaya
1500-1800m
1800-2100m
The probability of
obtaining less than 20in
1961(500mm) of rain a year 0-10%
The probability of
obtaining less than 30in
(760mm) of rain a year 20-30%
1961Mean Annual Rainfall
760-1010mm
0-10%
0-10%
1010-1270mm
(Climate, rainfall probabilities, temperature, sunshine & clouds, 1961)
Mean Monthly Rainfall
200
-1961 Map in PSU
Library
-average of 6 years
178
180
Rainfall (mm)
160
130
140
120
89
100
76
80
60
40
25
30
Jan
Feb
38
25
89
76
38
23
20
0
Mar
Apr
May
June
July
Aug
Sept
Oct
Nov
Dec
Month
myweather2:
No information
provide on time
period from which
the data was
collected
(Climate, mean monthly rainfall & humidity, 1961 and Weather2)
Rainy Days
myweather2
(Weather2)
Humidity
Relative Humidity (%)
Average Daily Relative Humidity
90
80
70
60
50
40
30
20
10
0
Jan
Feb
Mar
Apr May June July
Aug Sept Oct
Nov
Dec
Month
myweather2
(Weather2)
Temperature- Nyeri
myweather2
Nyeri and Othaya (1980)
•Mean annual Temp (C): 16-18
•Mean Max Temp: 22-24
•Mean Min Temp: 10-12
•Abs. Min Temp: 2-4
•Night Frost: Very Rare
(Weather2)
Wind
myweather2
(Weather2)
Length of Growing Period
FAO:
-Last updated in 2000
-averaged over 37
years
(Length of Growing Period, 2000)
Soil Information for Nyeri, Othaya and Lamuria
General Info:
The major soil types found in Kenya include: ferralsols, vertisols, acrisols, lixisols, luvisols, and
nitrisols. The main problems include: salinity/sodicity, acidity, infertility and drainage.
Othaya: Latitude: 0° -35’ 60” S (-0.567), Longitude: 36° 57’ 0” E (36.950)
-deep red soils with high fertility
-Mainly nitisols and andosols
-andic and chromo-luvic Phaeozems; andic and nito-chromic Cambisols
-Nitisols:
-mainly in highlands and on steep volcanic slopes
-develop from volcanic rocks
-good moisture-storage capacity
-good aeration
-organic matter cantnet, CEC (cation exchange capacity), and percent base
saturation all range from low to high
-mostly acidic (pH <5.5) due to leaching of soluble bases
-for optimal agriculture production:
-use manure and inorganic fertilizer
-Andosols:
-mainly in areas with steep slopes and high rainfall
-if rainfall exceeds 1000mm per year excessive leaching can occur
-porous soil
-high water storage capacity
-low bulk density
-usually low pH due to leaching of soluble bases and aluminum
-conditions favor high phosphorus fixation- therefore it is not available to plants
-optimal agriculture production:
-liming and fertilizer necessary
-Phaeozems have a surface layer that is high in humus and are good for growing wheat,
soybeans and pasturing cattle
- Cambisols make good agricultural land and tend to be very productive.
Nyeri: Latitude: 0° -24’ 0” S (-0.4167), Longitude: 36° 53’ 60” E (36.9500)
-same as Othaya
Lamuria: Latitude: 0° 11’ 0” S, Longitude: 36° 52’ 0” E
-poorly drained
-moderately deep to deep clay soil
-Vertisols; gleysols; other planosols; greyzems
-Vertisols:
-on very gently undulating to flat topography
-in semi-arid and sub-humid environments
-high clay content in subsoil (higher clay content in subsoil than in the top-soil)
-impermeable layer in the B-horizon therefore the soil has poor drainage
-low vertical and horizontal drainage
-very low workability of soil
-dark in color
-swelling type soil
-bowl shaped depressions (gilgai) may form due to the shrinking and swelling of
the soil in untilled soil
-during dry season deep and wide cracks develop
-Gleysols tend to be saturated with groundwater and are found in wetlands
-Planosols have high clay content in the subsoil
Sources of Information:
Agro-Climactic Zone Map of Kenya. [Map]. (1980) Kenya Soil Survey. Ministry Of Agriculture,
Nairobi. Retrieved 23 Jan. 2011 from
http://eusoils.jrc.ec.europa.eu/Esdb_Archive/EuDASM/Africa/images/maps/download/afr
_keacz2.jpg
Annual Rainfall for United States. The World Almanac. (1988). Retrieved 7 Feb. 2011 from
http://www.betweenwaters.com/etc/usrain.html
Climate, mean monthly rainfall & humidity. [Map]. (1961). The Survey. Retrieved from PSU
Earth and Mineral Sciences Library.
Climate, rainfall probabilities, temperature, sunshine & clouds. [Map]. (1961.) The Survey.
Retrieved from PSU Earth and Mineral Sciences Library.
Elevation. [Map]. (1996). Retrieved from
http://www.fao.org/countryprofiles/Maps/KEN/03/el/index.html
Falling Rain Genomics, Inc. (2010). Othaya, Kenya Page. Retrieved 4 Feb. 2011 from
http://www.fallingrain.com/world/KE/01/Othaya.html
Kenya National Bureau of Statistics. Retrieved 23 Jan. 2011 from http://www.knbs.or.ke/
Kenyan Soils. [Map]. Kenyan Soil Survey. Retrieved from http://www.infonetbiovision.org/default/ct/266/soilManagement
Length of Growing Period. [Map]. (2000). Retrieved from
http://www.fao.org/countryprofiles/Maps/KEN/03/el/index.html
Levoyageur. (2011). Retrieved 23 Jan. 2011 from http://www.levoyageur.net/weather-cityNYERI-OTHAYA.html
Office of the Prime Minister, Ministry of State for the Development of Northern Kenya and
Other Arid Lands, Resource Management Project II. (2008) Dec. Drought Monthly
Bulletin. Retrieved 3 Feb. 2011 from
http://www.aridland.go.ke/bullentins/2008/dec/nyeri.pdf
Orodho, Apollo Bwonya. (2001).Country Pasture/Forage Resource Profiles. Food and
Agriculture Organization Retrieved 24 Jan. 2011 from
http://www.fao.org/ag/AGP/AGPC/doc/counprof/Kenya.htm
Precipitation. [Map]. (2000). Retrieved from
http://www.fao.org/countryprofiles/Maps/KEN/06/pp/index.html
Soil Survey Institute Wageningen, The Netherlands. (1980). [Soil Map]. Exploratory Soil Map of
Kenya. Retrieved from http://library.wur.nl/isric/kaart/origineel/afr_keesm1.jpg
Sombroek. (1980). [Soil Map]. Exploratory Soil Map of Kenya. Retrieved from:
http://proceedings.esri.com/library/userconf/proc98/proceed/to850/pap841/p841.htm
Upper Tana: Landforms and Rivers. [Map]. (2000). Retrieved from
http://pdf.wri.org/kenya_atlas_11_uppertana_ch8_150.pdf
Water Resources: FAO: AQUASTAT (2002). Water Availability per Person per Year. Retrieved
3 Feb.2011 from http://www.unesco.org/bpi/wwdr/WWDR_chart1_eng.pdf
Weather2. Retrieved 20 Jan 2011 from http://www.myweather2.com/CityTown/Kenya/Nyeri/climate-profile.aspx
World Resources Institute. (2007). Nature’s Benefits in Kenya, An Atlas of Ecosystems and
Human Well-Being. Washington, DC and Nairobi: World Resources Institute. Retrieved
23 Jan. 2011 from http://pdf.wri.org/kenya_atlas_01_frontmatter_150.pdf