Volume 7 Article informations Phosphogypsum effect on soil, rainwater incubated and soil respiration Kaouther Ardhaoui Abstract Phosphogypsum (PG) is a byproduct issued by fertilizer industry, which has been used as soil fertilizer in many countries in the world for long time. The most positive effect of phosphogypsum is ameliorating soil properties and increasing crop yields. Recently, disquiets are growing related to the increase of the acidity and metal ions concentration in soils. This work is a study on the short term impact of using phosphogypsum, as an amendment in El Fja region (Mednine, Tunisia). Physico-chemical characterizations (pH, electrical conductivity, P2O5 concentration, chloride concentration, calcium and magnesium conentration) of rain water, incubated at room temperature with soil and also with a (soil, phosphogypsum) mixture during 37 days, were investigated. The dissolution of this product and its impurities in the first period of incubation releases the ions usuful for agricultural use like calcium, magnesium, sulphate and phosphate ions. In addition, the effect of amending phosphogypsum on the increase of organic carbon mineralisation, which is an indicator for soil respiration, was revealed. Key words: Arid zone, phosphogypsum, organic carbon mineralisation, water and soil incubation.