Dn. Mugendi et al., DECOMPOSITION OF CASSIA-SIAMEA LOPPINGS IN SEMIARID-MACHAKOS, KENYA, Arid soil research and rehabilitation, 8(4), 1994, pp. 363-372
The rate of decomposition of Cassia siamea Lam, prunings in an alley c
ropping system was investigated using litter bags in the semiarid area
of the Machakos District, Kenya, during the short rains of 1988 and t
he long rains of 1989. Cassia siamea had been grown as the hedgerow sp
ecies since 1983. Loppings were used as mulch incorporated into the so
il for green manuring. Approximately 70-90% of the loppings could deco
mpose exponentially within 60 days, a relatively low rate. Younger mat
erial decomposed faster in the long rains than older material in the s
hort 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 de
composition. Outside the rainy seasons, termite influenced discriminat
ion of decomposing material. Fungi had a role throughout, but bacteria
may be supposed to be the predominant agent within the rainy seasons.