http://repository.tuc.ac.ke:8080/xmlui/handle/123456789/23 2026-07-21T18:40:40Z 2026-07-21T18:40:40Z Nomé Sakané & Miguel Alvarez & Mathias Becker & Beate Böhme & Collins Handa & Hellen W. Kamiri & Matthias Langensiepen & Gunter Menz & Salome Misana & Neema G. Mogha & Bodo Maria Möseler & Emiliana J. Mwita & Helida A. Oyieke & Mark T. van Wijk http://repository.tuc.ac.ke:8080/xmlui/handle/123456789/625 2026-07-06T08:48:25Z 2012-08-20T00:00:00Z

Classification, Characterisation, and Use of Small Wetlands in East Africa Nomé Sakané & Miguel Alvarez & Mathias Becker & Beate Böhme & Collins Handa & Hellen W. Kamiri & Matthias Langensiepen & Gunter Menz & Salome Misana & Neema G. Mogha & Bodo Maria Möseler & Emiliana J. Mwita & Helida A. Oyieke & Mark T. van Wijk Small wetlands in Kenya and Tanzania cover about 12 million ha and are increasingly converted for agricultural production. There is a need to provide guidelines for their future protection or use, requiring their systematic classification and characterisation. Fifty-one wetlands were inventoried in 2008 in four contrasting sites, covering a surveyed total area of 484 km2 . Each wetland was subdivided into sub-units of 0.5–458 ha based on the predominant land use. The biophysical and socio-economic attributes of the resulting 157 wetland sub-units were determined. The wetland sub-units were categorized using multivariate analyses into five major cluster groups. The main wetland categories comprised: (1) narrow permanently flooded inland valleys that are largely unused; (2) wide permanently flooded inland valleys and highlands floodplains under extensive use; (3) large inland valleys and lowland floodplains with seasonal flooding under medium use intensity; (4) completely drained wide inland valleys and highlands floodplains under intensive food crop production; and (5) narrow drained inland valleys under permanent horticultural production. The wetland types were associated with specific vegetation forms and soil attributes

2012-08-20T00:00:00Z James K. Ndufa, * Stanley M. Gathumbi, Hellen W. Kamiri, Ken E. Giller, and Georg Cadisch http://repository.tuc.ac.ke:8080/xmlui/handle/123456789/624 2026-07-06T08:44:59Z 2009-11-01T00:00:00Z

Do Mixed-Species Legume Fallows Provide Long-Term Maize Yield Benefi t Compared with Monoculture Legume Fallows? James K. Ndufa, * Stanley M. Gathumbi, Hellen W. Kamiri, Ken E. Giller, and Georg Cadisch Th e deliberate planting of fast-growing N2–fi xing legume monoculture species in rotation with cereal crops can be an important source of N for soil fertility replenishment. We hypothesized that mixed-species fallows have a higher potential of giving longterm residual benefi ts in terms of biomass, nutrients, and quality of residuals leading to long-term nutrient supply to postfallow maize (Zea mays L.) crops. To test these hypotheses, two experiments were established in farmers’ fi elds on very fi ne Kandiudalfi c Eutrudox soils with monoculture and mixed-species fallows. Treatments included: sesbania [Sesbania sesban (L.) Merr.], crotalaria (Crotalaria grahamiana Wight and Arn.), pigeonpea [Cajanus cajan (L.) Millsp.], siratro [Macroptilium atropurpureum (DC.) Urb.], and calliandra (Calliandra calothyrsus Meissn.) as monoculture-species fallow and mixture fallows of sesbania + crotalaria, sesbania + pigeonpea, sesbania + siratro, or sesbania + calliandra compared with continuous maize cropping with or without N fertilizer, and natural weed fallow. Total aboveground biomass ranged from 4.1 to 20.5 Mg ha–1 for monoculture and 7.8 to 23.3 Mg ha–1 for mixed-species fallows. Recyclable fallow biomass N ranged from 70 to 313 kg ha–1 and there was a positive interaction in some mixtures leading to increased N accumulation. Postfallow maize yields for fallows over fi ve cropping seasons were 161–272% or 61–103% higher when compared with continuous maize without or with N fertilizer, respectively. Long-term postfallow eff ects on maize yield were linearly related to the amount of recycled fallow N yield. Th us, choice of fallow species to mix should be primarily driven by a better risk management strategy and an increased basket of multiple products and services.

2009-11-01T00:00:00Z Kibet Sitienei , 1,2 Hellen W. Kamiri,3 Gilbert M. Nduru,1 and David M. Kamau4 http://repository.tuc.ac.ke:8080/xmlui/handle/123456789/623 2026-07-06T08:42:24Z 2018-10-01T00:00:00Z

Nutrient Budget and Economic Assessment of Blended Fertilizer Use in Kenya Tea Industry Kibet Sitienei , 1,2 Hellen W. Kamiri,3 Gilbert M. Nduru,1 and David M. Kamau4 Kenya’s tea industry depends predominantly on imported compound NPK fertilizers to replenish nutrients removed through plucking. 'ese fertilizers cannot be easily manipulated for specific soils and tea clones. 'ey also frequently become hazardous within tea-growing environments. In this respect, two fertilizer blends containing NPKS 25 : 5 : 5 : 4 + 9Ca + 2.62Mg and NPKS 23 : 5 : 5 : 4 + 10Ca + 3Mg with trace elements have been produced commercially in the country. However, the extent to which the blended fertilizers may contribute to optimal economic gains without degrading the environment has not been determined. 'is was the knowledge gap that this study seeks to address. 'e goal of this study was to evaluate the economic efficacy of fertilizer blends with the aim of identifying optimal levels of application which would maximize tea productivity with minimal negative impacts on the environment. 'e study hypothesized that blended fertilizers maximize productivity of tea clones with minimal environmental damage. 'e fertilizer blends were evaluated in two study sites, i.e., Timbilil Estate in Kericho and Kagochi farm in Nyeri. 'e sites were selected purposefully, one in the eastern and the other in the western tea-growing areas. 'e trial was laid out in randomized complete block design with two fertilizer blends and the standard NPK 26 : 5 : 5 as control. 'e treatments were applied at four fertilizer rates (0 (control), 75, 150, and 225 kg·N·ha−1 ·yr−1 ), replicated thrice. Leaf samples were collected and analyzed for nutrient uptake as well as associated yields and economic trends. 'e economic optimum nitrogen rate (EONR) was achieved at 75 kg·N·ha−1 ·yr−1 at Kagochi with all fertilizers, while at Timbilil, EONR was variable, between 75 and 225 kg·N·ha−1 ·yr−1 with fertilizer types. 'is study has shown that, based on the economic point of view, Blend “A” was the most efficient and consistent fertilizer in production and economic returns across the two sites.

2018-10-01T00:00:00Z Catherine Waithira NJUGUNA, 1 Hellen Wangechi KAMIRI, 2 John Robert OKALEBO,1 Wilson NGETICH,1 Syphilline KEBENEY1 http://repository.tuc.ac.ke:8080/xmlui/handle/123456789/622 2026-07-06T08:40:24Z 2016-10-30T00:00:00Z

Evaluating the effect of plant population densities and nitrogen application on the leaf area index of maize in a reclaimed wetland in Kenya Catherine Waithira NJUGUNA, 1 Hellen Wangechi KAMIRI, 2 John Robert OKALEBO,1 Wilson NGETICH,1 Syphilline KEBENEY1 Maize is the main staple food in Kenya with over 90% of Kenyans relying on it. While the annual national consumption is increasing, the production of this crop has been on the decline in the last two decades. Maize production in Kenya fell by 33.4% in 2013 with Nyeri among the counties said to be grappling with the production of this crop. Land pressure is one of the major causes of decreased availability of food as well as soil depletion and encroachment upon fragile ecosystems such as wetlands. Nitrogen is a key nutrient in the production of maize, and its deficiency is a major factor limiting its production. This study investigated the effect of N application at 120 kg N/ha and maize density on the Leaf Area Index in reclaimed wetland soils in an experimental set-up comprising a randomized complete block design with three replications. The research was carried out in Nyeri County, Kenya. Leaf Area Index (LAI) was determined using the given SunScan formula. Measurements were done continuously until crop physiological maturity. Results indicated that the leaf area index increased with nitrogen application and reduced with spacing for most treatments. There were no significant differences between the two methods (Copy Method and SunScan). Leaf Area Index (LAI) was high in treatments containing nitrogen and high plant density. It was concluded that high plant density gives high LAI. 50 cm * 12.5 cm (-N) and 50 cm * 12.5 cm (+N) are the recommended plant densities for the site.

2016-10-30T00:00:00Z