Musyoka, Martha W.Adamtey, NoahBu¨nemann, Else K.Muriuki, Anne W.Karanja, Edward N.Mucheru-Muna, MonicaFiaboe, Komi K. M.Cadisch, Georg2021-04-132021-04-132019http://ir-library.ku.ac.ke/handle/123456789/21977An Article Published in Nutr Cycl AgroecosystTo 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.enIncubationMineralizationMineral-N releaseSynchronyOrganic input qualityNitrogen Release and Synchrony in Organic and Conventional Farming Systems of the Central Highlands of KenyaArticle