ALLEY 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,
University of Sri Jayewardenepura,Sri Lanka. 1999. All rights reserved.