Modelling of hillsides and lowlands soils fertility deterioration in the urban commune of n’zérékoré, republic of guinea, case of Nakoyakpala District

The objective of this study is to examine the deterioration of the fertility of hillside and lowland soils in the Nakoyakpala district, in the urban commune of Nzérékoré, Republic of Guinea. The methods used are documentary research, systematic random survey and physicochemical parameters analysis using photometry. The results reveal that 65% of farmers practice parallel crop, 60% of them use chemical inputs and 80% dump waste into ditches, lowlands and waterways. Thus the lowland soils are more humid with a rate of 46.1%, the nitrate content (NO3-) in the lowlands varies between 25mg/l and 20mg/l, while on the hillsides is between 15mg/l and 45mg/l. Ammonium (NH4+) is higher in the hillsides with 3.5 mg/l than the lowlands with 3 mg/l. The pH varies between 4 and 4.5.In view of results from surveys and physicochemical analyzes, it is clearly established the deterioration of the soil is mainly due to bad crops practices. To illustrate the soil fertility degradation, physicochemical parameters of Nakoyakpala district lowland and Hillside soils is compare to the same parameters recommended standadrs for fertile lowland and hillside soils. The results showed pH, Humidity, density and ammonium of lowland and hillside soils of Nakoyakpala are well below compared to the recommended standards. However in nitrate the behave well because they have values higher than the recommended standards.