Volume 9 Article informations Effect of ammonium and phosphorus, under controlled conditions, on functional properties in two contrasting soils Manel Allani, Hatem Ibrahim, Abdessatar Hatira, Iuliana Gabriela Breaban Abstract Over-supply of nitrogen and phosphorus as a mineral fertilizer can lead to disruption of the biochemical properties of soils. The aim of this research is to study the temporal evolution of the quantities of nitrogen and phosphorus mineralized in two agricultural soils to demonstrate the impact of changes in the physicochemical properties related to ammonium (NH4 + ) and phosphorus (PO4 3- ) applied to their availability in a vertic soils. A short-term incubation experiment of 6 weeks was carried out under controlled conditions of the laboratory, on two soils, one of Tunisian origin (Vertic Xerofluvents) and the second of Romanian origin (Vertisol). The two soils were subjected to two inorganic inputs, ammonium (NH4 + ) and phosphorus (PO4 3- ). Two different normality (0.5 N and 1N) of nitrogen and phosphorus were added in each soil and incubated at 25 °C and 30 ± 1 °C. These treatments were compared to samples from both control soils without input. The main results indicate that during the incubation period, the addition (NH4 + ) and (PO4 3- ), on both soils, resulted to an increase in ammonium availability at the beginning of the experiment and in phosphorus, at the same time pH decreases and salinity (electrical conductivity, CE) increases. This study shows the impact of nitrogen and phosphate amendments on the evolution of the physicochemical properties of soils from different pedoclimatic conditions. Key words: Incubation, Nitrogen, Phosphorus, Physico-chemical properties, Soil amendment, Vertisol.