Browsing by Author "Ngome, Ajebesone"

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Assessment of Technology Options Addressing Agricultural Production Constraints in Western Kenya
(Greener Journal of Agricultural Sciences, 2013-03-29) Mtei, Kelvin; Ngome, Ajebesone; Wambua, Stephen; Becker, Mathias
Poor soil fertility and weed infestation are among major constraints facing agricultural production in Western Kenya. Recommended technologies differ in resource requirement and their effectiveness are seasonal site-specific. On-farm experiments were conducted during 2008/09 cropping seasons on two soil types of western Kenya using maize as a test crop. Seven technology options were assessed on agronomic performance, resource requirement, and economic returns. Maize grain yield differed between cropping seasons with generally higher yields during long rainy season, and across soil types with organic manure-based options performing better on Ultisol than on Alfisol. Response of soil parameters reflected the amount of added nutrients and soil type with strongest effect of added N on Alfisol and of added P on Ultisol. All options significantly reduced weed biomass in the maize fields in the long (>90%) than in the short rainy seasons (>50%). Green manure-based option required more labour while mineral fertilizer-based options required largest capital. The economic net-benefit varied between -112 and +892 € ha-1 with highest values in organic manure-based options during short rainy season and in mineral fertilizer-based options during long rainy season. This example illustrates the need to define site-specific technology evaluation for successful targeting of technology options.
Fertility management for maize cultivation in some soils of Western Kenya
(Elsevier, 2011-12-01) Ngome, Ajebesone; Becker, Mathias; Mtei, Kelvin; Mussgnug, Frank
Soil fertility loss in Western Kenya is exacerbated by inadequate nutrient management and causes reduced maize yields. Given the diversity of soil types, cropping seasons, and the resource endowment of farmers, the magnitude of the soil fertility decline and the effectiveness of management options to counteract this decline is likely to differ. Five organic and inorganic management options were compared with farmers’ practice regarding their effects on soil fertility attributes and nutrient balances/use efficiencies in maize on three contrasting soils of Western Kenya and over two cropping seasons. Irrespective of the season, organic amendments were more effective than mineral fertilizers in enhancing soil carbon stocks and the labile and non-labile C fractions. The largest soil C content (4.1%) and C pool (72 Mg ha−1) were observed on the clay Nitisol after two seasons of reduced tillage, while the lowest C content (1.1%) and C pool (22 Mg ha−1) were observed on the sandy Acrisol with conventional tillage. Total soil N content was consistently higher with mineral than with organic fertilizer use and more so on Nitisol than on Ferralsol or Acrisol. The soil N supplying capacity increased with the application of both organic and mineral fertilizers and reached 210 mg kg−1 after two weeks of anaerobic incubation of the mineral N-amended Acrisol. Bray-I P content reflected the P application rates and was highest (50–66 mg kg−1) on the Acrisol with mineral P fertilizer use and lowest (1.5 mg kg−1) on the Ferralsol in the unamended control treatment. Partial N and P balances were generally positive except for the mineral N-amended treatments on the Nitisol. The efficiency of applied N varied from 29 to 135 kg kg−1 N with lowest values in the sandy Acrisol under reduced tillage. These differential responses to management options in different soil types were reflected in maize grain yields with highest cumulative yields of 4.7–9.4 Mg ha−1 a−1 in the Nitisol and 1.4–7.4 Mg ha−1 a−1 in the Acrisol and the Ferralsol. We may conclude that the tested technology options differentially affected soil fertility and production attributes. The extent of this response depended on the cropping season and the soil type, supporting the need for site-specific nutrient management and technology targeting.
Leguminous cover crops differentially affect maize yields in three contrasting soil types of Kakamega, Western Kenya
(Journal of Agriculture and Rural Development in the Tropics and Subtropics (JARTS), 2011) Ngome, Ajebesone; Becker, Mathias; Mtei, Kelvin
Maize production in smallholder farming systems in Kenya is largely limited by low soil fertility. As mineral fertilizer is expensive, green manuring using leguminous cover crops could be an alternative strategy for farmers to enhance farm productivity. However due to variability in soil type and crop management, the effects of green manure are likely to differ with farms. The objectives of this study were to evaluate Mucuna pruriens and Arachis pintoi on (i) biomass and nitrogen fixation (15 N natural abundance),(ii) soil carbon and nitrogen stocks and (iii) their effects on maize yields over two cropping seasons in Kakamega, Western Kenya. Mucuna at 6 weeks accumulated 1–1.3 Mg ha^{-1} of dry matter and 33–56 kg ha^{-1} nitrogen of which 70% was nitrogen derived from the atmosphere (Ndfa). Arachis after 12 months accumulated 2–2.7 Mg ha^{-1} of dry matter and 51–74 kg N ha^{-1} of which 52-63% was from Ndfa. Soil carbon and nitrogen stocks at 0–15 cm depth were enhanced by 2-4 Mg C ha^{-1} and 0.3–1.0 Mg N ha^{-1} under Mucuna and Arachis fallow, irrespective of soil type. Maize yield increased by 0.5-2 Mg ha^{-1} in Mucuna and 0.5–3 Mg ha^{-1} in Arachis and the response was stronger on Nitisol than on Acrisol or Ferralsol. We concluded that leguminous cover crops seem promising in enhancing soil fertility and maize yields in Kenya, provided soil conditions and rainfall are suitable