Browsing by Author "Coulson, C.L."

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    Decomposition of Cassia siamea loppings in semiarid Machakos, Kenya
    (1994) Mugendi, Daniel N.; Mochoge, B.O.; Coulson, C.L.; Stigter, C.J.; Sang, F.K.
    The rate of decomposition of Cassia siamea Lam. prunings in an alley cropping system was investigated using litter bags in the semiarid area of the Machakos District, Kenya, during the short rains of 1988 and the long rains of 1989. Cassia siamea had been grown as the hedgerow species since 1983. Loppings were used as mulch incorporated into the soil for green manuring. Approximately 70–90% of the loppings could decompose exponentially within 60 days, a relatively low rate. Younger material decomposed faster in the long rains than older material in the short rains. Nitrogen content and C/N ratios explain this result. They also meet critical values in the literature for nitrogen availability to the crop. Position in the alleys had no significant influence on decomposition. Outside the rainy seasons, termite activity appreciably influenced diminution of decomposing material. Fungi had a role throughout, but bacteria may be supposed to be the predominant agent within the rainy seasons.
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    Effect of incorporating Cassia siamea prunings on maize yield in an alley cropping trial in semiarid Kenya
    (1997) Mugendi, Daniel N.; Mochoge, B.O.; Coulson, C.L.; Stigter, C.J.; Sang, F.K.
    The influence of soil-incorporated Cassia siamea prunings on nutrient status of maize leaves, grain and yield was studied in an alley cropping experiment in semiarid Machakos, Kenya, during the 1988 long and short rainy seasons. The trial was established in 1983 and in all the seasons Katumani composite B maize was sown, except in the short rains of 1988 when Hybrid 511 was planted. Plots consisted of 3 cropped alleys between cassia hedges spaced at 3.6 m apart. The hedges were lopped at the beginning of every season (on-set of rains) and the prunings incorporated into the alleys one day before maize seeds were sown. The control plots had no hedges and hence no prunings were incorporated. Incorporation of prunings into the soil increased nutrient concentration in the maize leaves, grains and soil in the treatment plots compared to the controls. Maize grain yield on a per row basis was also higher in the plots that received prunings application compared to the controls. However, on an area basis, the yield increase was insufficient to compensate for the area lost to the Cassia siamea shrubs.