Alley cropping of maize with calliandra and leucaena in the subhumid highlands of Kenya: Part 2. Biomass decomposition, N mineralization, and N uptake by maize
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Date
1999
Authors
Mugendi, D.N.
Nair, P. K. R.
Mugwe, J. N.
O'Neill, M. K.
Swift, M. J.
Woomer, P.
Journal Title
Journal ISSN
Volume Title
Publisher
Kluwer Academic Publishers
Abstract
A major challenge in developing agroforestry approaches that utilize tree-leaf biomass for provision of N to crops is to ensure synchrony between the N released from decomposing prunings and N demand by crops. A study was conducted in the subhumid highlands of Kenya to assess the rate of decomposition and mineralization of soil-incorporated Calliandra calothyrsus Meissner (calliandra) and Leucaena leucocephala (Lam.) de Wit (leucaena) tree biomass and maize roots (Zea mays L.) both in an alley cropping and a sole cropping system. The amount of mineralized N peaked four weeks after planting (WAP) maize in all the treatments during both seasons of 1995. Cumulative mineralized N at week 20 ranged from 114 to 364 kg N ha−1 season−1, the absolute control treatment giving the lowest and the prunings-incorporated treatments giving the highest amounts in the two seasons. Total N uptake by maize, ranging from 42 to 157 kg ha−1 season−1, was lowest in the 'alley-cropped, prunings-removed' treatments, and highest in the 'non alley-cropped-prunings-incorporated' treatments. The apparent N recovery rate by maize was highest in the fertilizer applied treatments in the two seasons. Decomposition rate constants (kD) ranged from 0.07 to 0.21 week−1, and the rates among the different plant residues were as follows: leucaena < calliandra < maize roots. Nitrogen release rate constants (kN), ranging from 0.04 to 0.25 week−1, followed a similar pattern as the rate of decomposition with leucaena releasing the highest amount of N followed by calliandra and lastly by maize roots.
Description
DOI 10.1023/A:1006269217882
Keywords
chemical composition, mineral-N, N recovery, rate constants, synchrony
Citation
Agroforestry Systems 06-1999, Volume 46, Issue 1, pp 51-64