Enhancing Maize Productivity and Profitability using Organic Inputs and Mineral Fertilizer in Central Kenya Small-Hold Farms
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Date
2014
Authors
Mucheru-Muna, M.
Mugendi, D.
Pypers, P.
Mugwe, J.
Kung'u, J.B.
Vanlauwe, B.
Merckx, R.
Journal Title
Journal ISSN
Volume Title
Publisher
Cambridge University Press
Abstract
Declining land productivity is a major problem facing smallholder farmers today in Sub-Saharan Africa,
and as a result increase in maize grain yield has historically staggered behind yield gains that have been
achieved elsewhere in the world. This decline primarily results from reduction in soil fertility caused
by continuous cultivation without adequate addition of external nutrient inputs. Improved soil fertility
management practices, which combine organic and mineral fertilizer inputs, can enable efficient use of
inputs applied, and can increase overall system’s productivity. The trials were established at two sites
with different soil fertility status to determine the effects of various organic sources (Tithonia diversifolia,
Mucuna pruriens, Calliandra calothyrsus and cattle manure) and their combinations with mineral fertilizer on
maize grain yield, economic return and soil chemical properties. Drought spells were common during
the peak water requirement periods, and during all the seasons most (90%) of the rainfall was received
before 50% flowering. In good and poor sites, there was a significant (p < 0.001) effect of season on maize
grain yield. Tithonia diversifolia recorded the highest (4.2 t ha−1) average maize grain yield in the poor site,
while Calliandra calothyrsus gave the highest (4.8 t ha−1) average maize grain yield in the good site. Maize
grain yields were lower in treatments with sole fertilizer compared with treatments that included organic
fertilizers. The maize grain yields were higher with sole organics compared with treatments integrating
organic and inorganic fertilizers. Soil pHincrement was statistically significant in the solemanure treatment
in good and poor sites (t-test, p = 0.036 and 0.013), respectively. In the poor site, magnesium increased
significantly in the sole manure and manure + 30 kg N ha−1 treatments with t-test p = 0.006 and 0.027,
respectively. Soil potassium was significant in the sole manure treatment (t-test, p = 0.03). Generally the
economic returns were low, with negative net benefits and benefit cost ratio of less than 1. Inorganic
fertilizer recorded the highest net benefit and return to labour (p < 0.001 and <0.01, respectively) in the
good site. The treatments that had very high maize grain yields did not lead to improved soil fertility, thus
there is need for tradeoffs between yield gains and soil fertility management when selecting agricultural
production technologies.
Description
doi:10.1017/S0014479713000525
Keywords
Citation
Experimental Agriculture, Vol.50(2); 2014, pp 250-269.