Complementary effects of organic and mineral fertilizers on maize production in the small holder farms of Meru South district, Kenya.
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Date
2014-03-14
Authors
Mutegi, Edwin Mwiti
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Abstract
The Central highlands of Kenya are generally densely populated and declining land
productivity has been a major problem facing the smallholder farmers in the region. This
is mainly attributed to the mining of nutrients due to cropping without external addition
of adequate nutrients coupled with small land sizes which promotes continuous cropping
with limited scope for crop rotation and inadequate soil fertility replenishment. With this
background, a study was conducted on the Humic Nitisols in Mucwa location, Meru
South District in a complete randomized block design (CRBD) with ten treatments
replicated thrice. The general objective of the study was to determine the levels of
complementarities between organic and mineral N amendments on maize production.
The specific objectives included determination of the influence of organic and mineral N
sources on soil chemical properties, maize grain yields, N uptake and to economically
evaluate their .profitability. The results obtained revealed that the general soil fertility
parameters changed slightly with calcium, magnesium and potassium increasing in all
treatments. The organic carbon and total nitrogen was higher in treatments that received
sole organic N sources than in sole mineral N and a combination of organic and mineral
N sources. The highest maize grain yield of 4.8 t ha-1 and 4.2 t ha-1 were realized from
sole application of calliandra during the 2005 short rains and 2006 long rains cropping
seasons. The maize grain yield obtained in the organics and/or mineral N soil
amendments was higher than the yields obtained where the recommended mineral
fertilizers were used alone. Results obtained indicated that the use of either organic or
combined organic/mineral N soil amendment were superior to- using mineral N
amendment sources alone. The nitrogen (N) concentration in different parts of the maize
crop varied, with the grain having the highest N concentration, followed by the stover
during the 2005 short rain season. Sole application of calliandra recorded the highest N
uptake (170.8 kg N ha") while the control gave the lowest (49.31 kg N ha"), The results
on the average benefit-cost analysis was in the order of calliandra > tithonia > manure>
Tithonia + 30 kg N ha-1 > calliandra + 30 kg N ha-l> manure + 60 kg N ha-l > 60 kg N
ha-l > control> 30 kg N > 90 kg N ha". From the study findings, it's concluded that
organic and/or mineral N fertilizers replenish nutrient deficiencies, enhance crop yields
with improved N uptake and concentrations than sole mineral N inputs. This is an
indication of improved soil properties and less N losses from the soil-plant systems. The
organic and/or mineral N sources are also more economically profitable investment
amongst the smallholder farmers within the study area.
Description
Department of Environmental Science, 65p. The S 654 .M8 2008
Keywords
Organic fertilizers -- Kenya, Meru South, Biofertilizers