| dc.description.abstract | One of the major problems, facing the world today is that of meeting the food security
needs of an ever-increasing population over a limited arable land. To overcome this
problem, one option has been opening up more land for crop production through
irrigation in the arid and semi-arid lands (ASAL). In Kenya over 83% of the land mass is
in the marginal ASAL. Despite improving the livelihoods of farmers, irrigation often
contributes to environmental degradation.
The objectives of the study were; first, to evaluate the impact of smallholder irrigation on
the livelihoods of agro-pastoralists, soils and water resources along the Tana River in
Central division of Garissa District, secondly to determine the state of the soil quality in
the irrigated fields, and thirdly to assess the quality of irrigation water during the dry and
wet seasons. For livelihood survey, open and close ended questionnaire was administered
on 45 farming households. The information collected were household characteristics,
crop production and marketing, soil and water management, farm inputs, household food
security and wealth status. Soil samples were collected from randomly selected existing
irrigation schemes during the end of a dry season (October 2006) and end of a rainy
season (January 2007). Treatments consisted of three types of irrigation schemes
randomly selected based on number of years of irrigation and one non-irrigated site.
Similarly, water samples were collected from the same irrigation schemes along a canal
at distances of 0 m, 500 m and 1000 m away from the river. Descriptive and quantitative
statistics were used to analyze the data.
Results show that 98% of the farmers interviewed were male, of who 89% were married.
On average, a family had 10 members, while the education level of the farmers was low
with 38% of households interviewed having no formal education, 20% had adult literacy,
22% had primary education and 13% with secondary education.
Most of the farmers (78%) who grew crops owned livestock, mainly cattle, goats and
camels. About (93%) of the farmers grow crops both for home consumption and sale
with majority of the farmers using hired labour (71%). The area under crop production
had significantly increased (P'::: 0.021) over the years, leading to increased household
income, which 62% of farmers had used to acquire a variety of assets. Most of the
farmers (79%) in the irrigation scheme were food secure most of the time.
Soil bulk density and total porosity differed significantly (P>0.05) between the number of
years of irrigation and also between surface and sub-surface soils. Organic carbon varied
from 1.01 to 2.18 and 10.60 to 1.02 for surface and sub-surface soils after dry season,
while it varied from 1.40 to 1.90 and 1.02 to 1.43, after the rainy season for both surface
and sub-surface soils. Significant differences (P>0.05) were observed within and
between the two seasons with organic carbon increasing at the end of the rainy season
compared to end of dry season. The soil pH decreased at the end of rainy season
compared to the end of dry season, while it increased in sub-surface soils compared to
surface soils both at end of dry and rainy seasons.
For EC, significant differences were observed (P>0.05) within and between the seasons.
The dry season increased irrigation water salinity while the rainy season increased the
leaching levels, both cases having an effect on EC.
CEC varied within and between the two seasons with CEC significantly (P>0.05)
increasing at the end of rainy season. Calcium and magnesium significantly increased
(P>0.05) at the end of the rainy season in both surface and sub-surface soils compared to
end of dry season.
The pH of irrigation water fall within the normal range of 6.5 - 8.4 indicating the water
in the canal was safe for irrigation. Similarly the EC was 0.25 dS/m, hence it had no
salinity problem. However, significant differences (P>0.05) were observed between the
dry and rainy season where K+ and Cl ions increased after rainy season, but the chloride
levels were also within the accepted range «4mell). From the results, irrigation water
quality varied with season, but on average the water quality fall in the low salinity and
low sodium hazard class.
It is recommended that to boost the fanners efforts and to ensure higher incomes, a
marketing system for the high value horticultural crops be improved especially, for
tomatoes and mangoes whose prices fluctuate widely. It is also recommended that the
scheme management committees be strengthened through capacity building. The
continuous use of traditional fanning implements like plain jembes at shallow depth ha
resulted in increased surface soil compaction, resulting in decreased water flow, therefore
fanners should be advised to frequently practice deep ploughing, such as ripping and subsoiling
to break hardpans and compacted soils to improve soil structure which will
translate into improved crop water performance, thus increased yields. Finally, it's
recommended that further studies be carried out to determine the causes of irrigation
water quality variations with season, and variation of soil physical and chemical
properties with depth. | en |
