The influence of solid urban waste compost and nitrogen-mineral fertilizer on growth and productivity in potatoes

The influence of solid urban waste (SUW) compost and nitrogen (N)-mineral fertilizer on the growth and productivity in semi-early harvest potatoes (Solanum tuberosum L., var. 'Edzina') was studied over a period of three years. Nine treatments derived from a factorial combination of 3 levels of SUW compost (0, 18, 36 T.ha(-1)) and 3 levels of N-mineral fertilizer (0, 125, 250 Kg N ha(-1)) were carried out on a sandy, moderately fertile plot. The applications of SUW compost and N-mineral fertilizer showed a stimulation in plant development with respect to the non-treated controls. The mineral fertilizer treatment gave markedly higher results. Plant response to the combined mineral fertilizer-compost treatments demonstrated a tendency towards saturation within each level of application. Potato productivity results indicated that this crop reacts strongly and positively to an application of N-mineral fertilizer, but only slightly to the treatment levels of compost considered in the study. As a consequence of the application of SUW compost, the application-response graphs reveal a reduction in the optimal levels of N-mineral fertilizer application and an increase in the efficacy of the mineral fertilizer.