Changes in soil physico-chemical and biological quality after two decades of forest soil conversion to agricultural land

The development of agriculture to the detriment of the forest is one of the strongest pressures, essentially anthropogenic. The particularity of this study was that the traditional agricultural practice used was low intensity agriculture (fallow period) since the first conversion. The experiment was conducted in the Keroua forest, Saida Province, north-western Algeria. Soil samples from two experimental areas were collected at depths ranging from 0 to 10 cm. The findings came from the statistical analysis of the data, some of which revealed the sensitivity of this ecosystem. The conversion of the forest soil to agricultural land increased the alkalinity of the soil (pHH2O increased by 0.16 units), and the acidification of the soil with a significant decrease in pHKCl values (by 0.24 units). Moreover, the organic matter content in the converted soil decreased by more than 50%, while the physical characteristics changed slightly with a decrease in moisture content and water holding capacity and an increase in bulk and real density. Meanwhile, the permeability and total porosity did not change in the two areas. For biological properties, basal respiration and microbial biomass decreased by more than 45% in the converted soil compared to the forest soil.