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Diverse tree species when employed in agroforestry systems may serve as an alternative to increasing soil fertility through nitrogen fixation. However, it is not clearly known how intercropping maize and banana with Sesbania sesban, Calliandra callothyrsus and Leucaena diversifolia may affect growth of maize and banana. The purpose of this study was to evaluate the effect of intercropping agroforestry trees species with maize and banana on the growth, chlorophyll content and yield of maize and banana. Field experiment was laid out at Kenya Agricultural Livestock and Research Organization farm (KALRO) located in Kisii County. The Williams varieties of banana of the same age were obtained from KALRO--Thika and Hybrid seed maize, H513 obtained from Kenya seed company, Kisumu. The agroforestry tree seedlings were spaced: 0.5m by 1m, 0.9m by 0.9m by 0.6m deep and 0.3m by 0.75m between banana and maize respectively. Three replicates were used with seven treatments of Pure maize, pure banana, maize-banana-Calliandra, maize-banana-Leucaena, maizebanana- sesbania, maize-banana and maize-fertilizer, all in a randomized complete block design. Data on maize growth and chlorophyll content was collected at intervals of 2 weeks which commenced 30 days after planting while yield was determined at the end of growing seasons. Data was subjected to the Analysis of Variance. Maize plants and banana that were intercropped with Sesbania sesban had significantly (P≤0.05) highest growth, chlorophyll content and yield compared to other treatments. Therefore, Sesbania sesban is recommended as a suitable agroforestry tree species for intercropping with maize and bananas. [ABSTRACT FROM AUTHOR]

Abstract A field experiment was performed in eastern Kenya to estimate N2 fixation by Sesbania sesban over an 18-month period using the 15N dilution method. The influence of three reference species, Senna spectabilis, Eucalyptus saligna and Grevillea robusta, on the estimates of N2 fixation was also assessed. Percentage Ndfa (nitrogen derived from the atmosphere) was calculated based on foliar atom excess (FAE), above-ground atom excess (AAE) or whole tree atom excess (WAE) data. The differences in atom% 15N excess values between species and plant parts are presented and discussed. We recommend the use of several reference species for estimating %Ndfa and that the different results obtained should be carefully considered in relation to the issues being addressed. In this study, Senna was the most suitable of the three reference species because its N uptake pattern and phenology were very similar to those of Sesbania. When well established, the amount of N fixed by Sesbania accounts for more than 80% of its total N content, according to FAE-based estimates. We estimated the Ndfa by Sesbania after 18 months to between 500 and 600 kg ha-1 , depending on whether FAE, AAE or WAE data were used and on the choice of reference species. The substantial accumulation of N in planted Sesbania highlighted its potential to increase the sustainability of crop production on N-limited soils. We consider the 15N dilution method to be appropriate for quantifying N2 fixation in improved fallows in studies, similar to this one, of young trees with high N2-fixing ability. [ABSTRACT FROM AUTHOR]

Examines the effects of planted fallows of Sesbania sesban and Calliandra calothyrsus on soil inorganic nitrogen dynamics and subsequent maize crops in Kenya. Determination of ground biomass and nitrogen content; Soil organic matter; Effect of tree fallows on subsequent maize crops.

Examines the seedling inoculation test for Sesbania sesban and other Sesbania species in Kenya. Susceptibility of S. sesban to Mesoplatys ochroptera; Resistance of S. cinerascens to M. ochroptera; Measurement on the leaf consumption and larvae abundance of M. ochroptera.

An experiment in western Kenya tested the effects of six inoculum levels (0, 80, 400, 800, 2000 and 4000 eggs per 100 cm[sup 3] soil) of Meloidogyne javanica on nematode infection and growth of two Sesbania sesban provenences (Kakamega and Kisii) in six soils with sand contents of 26 to 82%. At 1 month after sowing, nematode infection, gall index and seedling mortality increased with inoculum level and sand/clay ratio. Gall index decreased and seedling growth improved with extractable cations, particularly calcium. At 3 months, nematode infection and damage were affected neither by soil texture nor by extractable cations. However, nodulation and plant growth decreased with increasing inoculum levels in all soils. Soils with higher cations and inherent fertility were less prone to nematode infestation and sustained better Sesbania growth irrespective of soil texture. It appears that as Sesbania grows it develops tolerance to M. javanica, suggesting that nematode infection is important at seedling stage primarily in determining stand establishment and early growth. Kisii provenance was more tolerant to the nematode and more productive than Kakamega. There is a need for screening a wide range of Sesbania germplasm for nematode resistance to select appropriate provenances and exploring low cost methods to minimise nematode damage to Sesbania at establishment stage. In einem Versuch in Westkenia wurde die Wirkung von sechs Inokulumstufen (0, 80, 400, 800, 2000 und 4000 Eier je 100 ml Boden) von Meloidogyne javanica auf die Nematodeninfektion und auf das Wachstum von zwei Herkünften von Sesbania sesban (Kakamega und Kisii) in sechs verschiedenen Böden mit Sandanteilen zwischen 26 und 82% untersucht. Einen Monat nach der Aussaat stiegen die Nematodeninfektion, der Vergallungsindex und die Keimlingssterblichkeit mit der Inokulumsgrösse und dem Sand/Lehm-Verhältnis an. Der Vergallungsindex nahm ab, und das Keimlingswachstum verbesserte sich mit dem Gehalt an extrahierbaren Kationen, insbesondere Kalzium. Nach 3 Monaten wurden Nematodeninfektion und Schaden weder durch die Bodentextur noch durch die extrahierbaren Kationen beeinflusst. Die Gallbildung und das Pflanzenwachstum nahmen jedoch in allen Böden mit steigenden Inokulumsstufen ab. Böden mit einem böheren Gehalt an Kationen und natürlicher Fruchtbarkeit neigten weniger zu Nematodeninfektionen und unterstützten das Wachstum von Sesbania unabhängig von der Bodentextur. Anscheinend entwickelt Sesbania mit zunehmendem Wachstum eine Toleranz gegenüber M. javanica. Das weist daraufhin, dass eine Nematodeninfektion im Keimlingsstadium in erster Linie wichtig ist für die Entwicklung des Standplatzes und für das frühe Wachstum. Die Herkunft Kisii war toleranter gegenüber den Nematoden und auch produktiver als Kakamega. Es muss eine breite Palette von Sesbania-Genplasmen auf Nematodenresistenz geprüft werden, um geeignete Herkünfte zu selektieren und preiswerte Methoden zur Minimierung des Nematodenschadens an Sesbania im frühen Entwicklungsstadium auszuprobieren. [ABSTRACT FROM AUTHOR]