| dc.description.abstract | Three experiments were conducted on intercropping beans with
low and high density Arabica coffee trees pruned to different canopy
densities. Growth and yield components of bean plants were measured
while clean coffee yields and quality were assessed to determine how
the two intercrops interact when grown in mixtures of varying proportions.
Dry bean plants interp1anted in low density coffee dessicated
the top Boil which resulted in lower quality coffee beans than that obtained
from mulched coffee. Bean plants grown directly under the dense coffee
canopy were etiolated, had fewer branches, pods and seeds per plant
than dry bean plants grown in the wider space between the coffee trees.
Assessment of dry bean seed yield per planted row showed that only the
central 90cm to 120cm strip between the coffee rows was suitable for
interplanting with beans.
Low density coffee pruned .on capped multiple stem system carried
the bulk of its crop in the top half of the canopy and the removal of the
lower half of the canopy had no significant effect on clean coffee yields.
Alteration of pruning time in the year had no significant effect on clean
coffee yield, though the quality could be affected due to the timeliness
of opening up the canopy for effective penetration of pesticides to control
diseases.
Bean plants interplanted in h~h density coffee in full production
developed long internodes, few branches, pods and seeds per plant,
culminating in low yields. The removal of the coffee canopy by block
stumping resulted in viBorous grQwth of interplanted beans which developed
short internodes, increased branching, podding and seed setting
and consequently high seed yield. Application of calcium ammonium
nitrate fertilizer significantly increased the bean Beed yields.
Neither the nitrogenous fertilizer nor intercropping coffee with different
bean rows per coffee inter-row space s~ificantly affected the clean
coffee yields. The dry bean yields increased with the rise in the number
of the bean rows per coffee inter-row space. Interplanting coffee with
beans increased the proportions of grade TT and thus lowered the quality
of the clean coffee from the intercropping system due to soil moisture
stress.
Intercropping Yield Advantage Ratio (IYAR) is proposed as a measure
of yield advantage achievable when an annual crop is interplanted in an
established perennial crop. The IYAR is obtained by dividing the sum of
the interplanted perennial crop yields in a cropping cycle and the annual
yield of the annual intercrop by the sole perennial crop yield in a cropping
cycle. An IYAR value greater than unity confers yield advantage to
the perennial/annual intercropping system.
Due to the adverse shading effect of the dense coffee canopy on
undersown bean plants, the only suitable period in the coffee cropping
cycle for successful intercropping with beans is during the change of cycle,
when the coffee canopy is drastically reduced for about two years, provided
the soil fertility is high and appropriate to both intercrops. The main
findings of this study were incorporated in the standard recommendations
on intercropping dry beans in Arabica coffee in Kenya under Technical
Circular No. 51 of 1982. Three to six dry bean rows may be intercalated
in the coffee inter-row space during the first two years of young coffee
or in mature coffee undergoing the change of cycle. | en |
