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Nitrogen release and synchrony in organic and conventional farming systems of the Central Highlands of Kenya

Musyoka, Martha W.; Adamtey, Noah; Bünemann, Else K.; Muriuki, Anne W.; Karanja, Edward N.; Mucheru-Muna, Monica; Fiaboe, Komi K.M. and Cadisch, Georg (2019) Nitrogen release and synchrony in organic and conventional farming systems of the Central Highlands of Kenya. Nutrient Cycling in Agroecosystems, 113 (3), pp. 283-305.

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Online at: https://link.springer.com/article/10.1007/s10705-019-09978-z

Summary

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 insufficient-asynchrony 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.


EPrint Type:Journal paper
Keywords:Incubation, Mineralization, Mineral-N release, Synchrony, Organic input quality
Subjects: Soil > Soil quality
Crop husbandry > Composting and manuring
"Organics" in general > Countries and regions > Africa
Research affiliation: Switzerland > FiBL - Research Institute of Organic Agriculture Switzerland > Soil Sciences
Switzerland > FiBL - Research Institute of Organic Agriculture Switzerland > International Cooperation
Kenya
Germany > University of Hohenheim
ISSN:online: 1573-0867, Print: 1385-1314
DOI:https://doi.org/10.1007/s10705-019-09978-z
Deposited By: ADAMTEY, Dr Noah
ID Code:36379
Deposited On:23 Aug 2019 12:28
Last Modified:23 Aug 2019 12:28
Document Language:English
Status:Published
Refereed:Peer-reviewed and accepted

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