Nitrogen Release and Synchrony in Organic and Conventional Farming Systems of the Central Highlands of Kenya
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Date
2019
Authors
Musyoka, Martha W.
Adamtey, Noah
Bu¨nemann, Else K.
Muriuki, Anne W.
Karanja, Edward N.
Mucheru-Muna, Monica
Fiaboe, Komi K. M.
Cadisch, Georg
Journal Title
Journal ISSN
Volume Title
Publisher
Springer Nature
Abstract
To match Nitrogen (N) supply to crop N
demand, it is essential to understand N release and
uptake patterns in different farming systems and crops.
To assesses the dynamics of N released in organic and
conventional systems and potential synchrony and
asynchrony in crop N uptake, a study was conducted
over three cropping seasons (potato, maize and leafy
vegetables) at two sites in the Central Highlands of
Kenya. Mineral-N release and synchrony were monitored
in conventional and organic systems at high
(recommended N, P, pesticides and irrigation) and low
input (low N, P, pesticide use and rainfed) systems.
Mineral-N release was assessed using in situ buried
bags and N synchrony was measured by the daily
differences in N fluxes. The percentage of N applied
released during potato (38%) and vegetable (44%)
cropping seasons were similar between systems.
However, under maize strong temporal N immobilization
from inputs occurred, particularly at Thika,
related to the poor quality of manure and compost
(lignin:N ratio[13). In all systems, excess-asynchrony
of available N was pronounced during vegetative
stages and at harvest, while insufficientasynchrony
occurred at reproductive stages. During potato cropping season at Thika, Org-High showed
highest positive N fluxes ([20 kg N ha-1 day-1) at
planting and tuber bulking stage. At early stages of
maize and vegetables Org-Low and Org-High experienced
up to 5 times larger negative N fluxes
(insufficiency) compared to conventional treatments
at Chuka site. The study recommends reducing N
applications at planting and increasing N dosages at
reproductive stages of crops.
Description
An Article Published in Nutr Cycl Agroecosyst
Keywords
Incubation, Mineralization, Mineral-N release, Synchrony, Organic input quality