Agronomic valorization of composted sludge in Tunisia

The objective of this work is to monitor the content of organic matter, carbon, potassium, phosphorus and trace elements in soils amended with sewage sludge compost and poultry manure at a rate of 3 tons per hectare respectively. The different amendments applied increase the amount of organic stock, fertilizing elements and trace elements in the soil compared to the control. Throughout the organic carbon monitoring, the soil amended with poultry manure had an organic carbon content of 1.47%, which is an increase of about 107% compared to the unamended soil. However, after a compost amendment, the organic carbon content of the soil increased to 1.26%, an increase rate of 77.5%. The contribution of organic amendments to the increase in soil available phosphorus is quite significant. Indeed, compared to the control, compost and poultry droppings provided 183.4% and 226.7% of available phosphorus respectively. Regarding exchangeable potassium, compost and poultry droppings provide respectively 89.77% and 110.71% more exchangeable potassium compared to the control.