Although the importance of organic amendments on arid soils of semi-arid and arid lands in improving long-term soil fertility, the excessive use of these amendments may induce the mineralization of the soil’s native organic components. Thus, this study focused on the examination of the impact of the use of three different amendments, sewage sludge, compost, and horse manure on nitrogen soil dynamics as well on the physico-chemical characteristics (soil texture, nitrogen cycle, and carbon concentration) and plant characteristics (morphology and production). In this context, the present work discusses one of the major issues challenging sustainable agriculture development related to increasing land degradation, soil salinization, and fertility loss. The three amendments were applied on the soil collected at the Institute of Arid Regions of Gabes. The findings of these experimental trials indicated that compost seems to be the most valuable organic amendment that may be used for an adequate supply of nitrogen and optimal benefits for plant growth. The highest mineral nitrogen content was found in the treatment with sludge. The manure-based treatment had the highest carbon/nitrogen ratio (C/N=25). The effects of the amendments were well reflected in the growth and production of bean plants after one year from the amendment. An increase in biomass was observed in the amended pots. The highest increase in pods biomass was obtained in the pots amended with sewage sludge and vegetable compost followed by household manure treatment.
Keywords: carbon mineralization, soil fertility, bean morphology, pods number