Effects of tannery wastes with or without chromium on soil nitrification in arid regions (Marrakech, Morocco)

The present study is concerned with a incubation process of following the e volution of NH4+ in two different soils (clay and sand) which receive two t ype of waste of tannery, that is tanned waste (which are full of chromium) and untanned ones. The obtained results indicate that the elimination proportion of the NH4+ i s higher within an amendment by untanned waste than by tanned ones, While the concentration of tanned of waste increases, the oxidation of NH4 decreases. This is probably linked to the chromium concentration in brough t by the tanned waste. The obtained results reveal also that the oxidation of NH4+ is the function of the soil nature. This was also confirmed by dete rmining the inhibition constancy (Ki) of Cr, The inhibition of the nitrification caused by different chromium concentrat ions is higher in the clay soil (0.99 g Cr/kg MS) than in tpe sand soil (2. 38 g Cr/kg MS). Nitrification is also influenced by temperature.