Effects of Lime, inorganic P and inoculation on Soil Chemical properties and Grain Yields of Maize and Soybean in Western Kenya
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Date
2013-10-17
Authors
Onyango, Maurine Akinyi
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Abstract
Low crop responses to fertilizer application among small holder farms are common
phenomena in degraded acidic soils of western Kenya. Continuous growing of maize
without commensurate soil nutrient replenishment coupled with application of soil
acidifying fertilizers, especially Di-ammonium Phosphate (DAP) and Sulphate of
ammonia (SA) have aggravated the soil acidity problem. An on-farm trial was sited
in Shianda sub-location, East Wanga division in Mumias district, Western province,
Kenya during the 2011 long rain (LR) and short rain (SR) seasons to determine the
effect of lime, inorganic P, inoculation on soil chemical properties and yields of
soybean (Glycine max L.) and maize (Zea mays L.). The treatments included, 2 lime
rates (0, 2.5 t/ha), 2 inorganic Prates (0, 30 kg P/ha) with or without inoculation
(Rhizobium japonicum) of soybean. The eight treatments were arranged as factorial
in RCBD with four replicates. All data were analyzed with the ANOV A procedure of
the GENST AT statistical software and treatment means separated using least
significance difference at (P < 0.05). Regression analysis was performed to examine
relationships between plant and soil parameters. Benefit-cost analysis was performed
on maize and soybean grain yields to determine the treatments with the most
profitable returns. A combination of Lime + P + inoculation recorded the highest
maize (4490 kg/ha, 3470 kg/ha) and soybean (970kglha, 830kglha) grain yields
during the first and second seasons, respectively. Sole P treatment gave a higher
average nodule number per plant and plant biomass (g), respectively (8 and 21.8)
than sole inoculation (4 and 19.2) and sole lime treatments (2 and 16.8) during the
first season. Lime application at Z.5 t/ha increased soil pH from 4.9 to 5.58. Increase
in soil available P was in the order' of lime> P > inoculation (9.35 > 6.50 > 5.10)
mg/kg. Sole lime treatment proved 'to be a more profitable investment for the farmers
as it gave. a net benefit of Ksh 89,015.20 with a benefit-cost ratio (BCR) of 2.2.
Therefore, integration of lime, inorganic P and inoculation needs to be disseminated
among small-scale farmers in western Kenya for improved maize and legume
production.
Description
Department of Agricultural Resources Management (ARM), 87p. The S 627 .C57O5 2013
Keywords
Soil degradation --Control --Kenya