Nitrogen is an important element of soil fertility. Indeed, it is essential for the plant and it is one of the essential factors of the yield and vegetables production. In the soil, nitrogen, which is mainly in organic form. Their mineralization is closely related to environmental conditions: temperature, humidity, aeration and above pH.So the soil fertility can be determined from an abacus proposed by Dabin (1970) which is a function of the total nitrogen content and the pH which proposes 5 scales of fertility (1 to 5).

The results show that soils around the quarry and the soil under rehabilitation can be divided into 2 groups:- bad soils (Assou-kondji and the area under rehabilitation)- poor soils (Nyinda- Kondji , Ahlimegni-Kondji, Anagonou-Kpota and Ziome Kondji)
It appears that:
- all the agricultural soils of the zone and the soil at the end of the rehabilitation are poor in nitrogen, potassium and phosphorus. It is important to cultivate on these soils legumes and other green manures which will regenerate the fertility of these soils.
- In particular, the Nyinda-kondji, Ziome-kondji, Anagonou-kpota and Assou-kondji soils are very poor in organic matter. The addition of composts and gren manure can also help to raise the level of organic matter in these soils.
The geoecological map will help us to better see the localization of the different types of soils according to their state of degradation.
Thanks to QLA!