Soil fertility technologies for increased food production in Chuka, Meru south district, Kenya
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Date
2003
Authors
Mucheru, Monicah Wanjiku
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University
Abstract
The high population pressure in Chuka has led to continuous cultivation with minimal
additional of inputs, leading to soil nutrient depletion. Research work has reported positive
results from the use of manure and biomass from tithonia, calliandra, leucaena, mucuna and
crotalaria for soil fertility replenishment. In relation to this a multidisciplinary farmers
participatory trial was established in Chuka Division, Meru District, to offer small-scale
resource poor farmers feasible soil nutrient replenishmenttechnologies.
The experiment was set up in a randomized complete block design with 14 nutrient
replenishment treatments (technologies) replicated thrice. At the beginning and at the end of
the study soil was sampled at 0-15 cm depth and the samples analysed for pH, Ca, Mg, K, C,
N, and P. At the end of the 2000/2001 short rains season and 2001 long rains season soil
samples were taken at 0-30, 30-100 and 100-150 ern, for nitrate and ammonium analysis. All
the treatments received an equivalent of 60 kg N ha' except the herbaceous legume
treatments where the amount of N was determined by the amount of the biomass harvested
and incorporated and the absolute control t~ent that received no inputs. Net benefit and
benefit-cost analysiswere conducted using farm gate prices.
The results indicate that soil fertility increased slightly in all the treatments (except the
control) over the two years of the study period. The average maize grain yield across the
treatments was 1.1, 5.4, 3.5 and 4.0 Mg ha-1 during the 2000 long rains, 2000/2001 short
rains, 2001 long rains and 2001/2002 short rains seasons respectively. The poor yields in the
2000 long rains and 2001 long rains seasons were attributed to the poor rainfall received in
these two seasons. On average tithonia with half recommended rate of inorganic fertilizer
recorded the highest (4.8 Mg ha') maize yield followed by sole tithonia (4.7 Mg ha').
VI
The highest average concentration (144.8 and 115.5 kg N ha') of mineral N was
recorded at the 30-100 em soil depth at the end of both the 2000/2001 short rains and 2001
long rains respectively. The lowest average concentration (67.1 kg N ha') was recorded in the
100-150 em soil depth during the 2000/2001 short rains while during the 2001 long rains the
0-30 cm depth recorded the lowest concentration (52.3 kg N ha"). The residual mineral N in
the 100-150 em soil depth doubled at the end of the long rains 2001 compared to what was
present at the end of short rains 2000/2001 season in all the treatments. This shows that there
is a substantial amount ofmineral-N that is being leached below the rooting systems of maize.
Sole tithonia was ranked as the best treatment, while, the control was ranked as the
poorest treatment by both the farmers and future farmers (students). The treatment ranking by
both groups was closely related to the actual maize grain yields attained later at the end ofthe
season. Out of the 171 farmers who attended the 3rd field day, 153 farmers (90%) indicated
willingness to take the technologies to their farms. Sole leucaena and calliandra were the most
cost effective technologies with a benefit/cost ratio (BCR) of7.3 while sole tithonia followed
closely with a (BCR of 6.9) through out the four seasons.
Description
Department of Environmental Education, 86p. 2003, S 654.M6