Differential response to tree fallows in rotational woodlot systems In semi-arid Tanzania: post-fallow maize yield, nutrient uptake, And soil nutrients
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Date
2008
Journal Title
Journal ISSN
Volume Title
Publisher
elservier
Abstract
Agroforestry tree species producing high quality litter may enhance post-fallow soil nutrient availability and crop yields through
mineralization of soil organic matter and green manure. A split-plot field experiment was used to evaluate maize yield and soil N and P status
after fallowing indigenous and exotic tree species of contrasting litter quality. Responses were compared with recommended inorganic
fertilizer use. The objective was to assess efficacy of 5-year tree fallows in improving soil productivity to screen species for increased crop
yield under rotational woodlot culture, an agroforestry system mainly used for on-farm fuelwood production in semi-arid Tanzania. Post-
fallow maize yield and soil nutrients differed significantly among tree fallows. Low C:N and L:N ratios enhanced nutrient release from slash.
Acacia polyacantha (indigenous) and Gliricidia sepium fallows doubled maize yield compared to the natural fallow probably due to high soil
N and P levels resulting from net release by high quality foliage. First season maize yield was similar to that from combined N and P fertilizers
indicating high capacity of the fallows to improve crop yields and reduce fertilizer inputs usually unaffordable to small-scale farmers.
Comparatively low maize yield and soil N and P levels after exotic Acacia crassicarpa and Acacia mangium fallows were attributed to net N
immobilization by poor quality litter during growing seasons. This study suggests that rotational woodlot systems utilizing tree species with
high litter quality can improve both post-fallow maize yield and soil fertility as well as produce sufficient fuelwood. In this aspect, A.
polyacantha would be the most appropriate species.
Description
Journal article
Keywords
Acacia, Litter quality, Maize yield, Semi-arid, Semi-arid, Woodlot