CROPPING AS AN ALTERNATIVE TO SHIFTING CULTIVATION IN THE DRY ZONE
K M A Kendaragama
Field Crop Research and Development Institute, Maha Illuppallama
An investigation was initiated was in 1977 and maintained since then at
the Field Crops Research and Development Institute, Maha Illuppallama
to study the possibility of introducing alley cropping as an alternative
to shifting cultivation for rainfed uplands in the dry zone. An experimental
plot planted with gliricidia (Gliricidia sepium) and an adjacent bare
plot were selected for this study. Maize (Zea mays) was planted in Maha
and Sesame (Sesamum indicum) in Yala in both plots since 1980. Biomass
production, soil fertility characteristics, weed growth and finally grain
yields of companion food crops in the alleys and bare plots were compared
in this study.
Results showed that the alley cropping a) generates an additional biomass
of 6 t/ ha/ year mainly in the form of green manures b) increases soil
organic matter status c) provides about 150 kg N/ ha/ year for the companion
crops through tree loppings d) maintains soil pH d) recycles bases particularly
potassium within the system f) improves microbiological activities in
soil mainly due to increase in bacteria and algae populations and g) suppresses
weed infestation particularly due to control of grass weeds. However,
a depletion of P in soil was observed with the introduction of trees in
alley plots. Nevertheless, better yields were obtained from companion
crops under alleys.
This long term field investigation showed that alleys cropping is promising
on rainfed uplands in the dry zone. Thus, introduction of alley cropping
to shifting cultivation areas helps to reduce further forest land clearing
while settling crop cultivation and simulating forest conditions on existing
farm lands. This paper discusses the results in detail.
Department of Forestry and Environmental Science,
of Sri Jayewardenepura,Sri Lanka. 1999. All rights reserved.