Assessment of Earthworm Viability and Soil Health after Two Years of Raw and Composted De-Inking Paper Sludge Amendment

• Published in: Agriculture (Basel) 2023-03, Vol.13 (3), p.547
• Main Authors: Zoghlami, Rahma Inès, Toukabri, Wael, Boudabbous, Khaoula, Hechmi, Sarra, Barbouchi, Meriem, Oueriemmi, Houda, Moussa, Mohammed, Bahri, Haithem
• Format: Article
• Language: English
• Subjects: Agricultural wastes; Arid regions; Arid zones; chemical fertility; Chemical properties; Clay loam; Clay soils; Composting; Contaminants; de-inking sludge; Deinking; earthworms; Environmental impact; Food security; humic fractions; Landfills; Manures; Organic matter; Organic soils; Phosphorus; Porosity; Potassium; Printing-ink; Semi arid areas; Semiarid lands; Sludge; Sludge treatment; Soil amendment; Soil chemistry; Soil contamination; Soil fertility; Soil improvement; Soil organic matter; Soil porosity; Soil properties; Soil quality; Soil stability; Soil treatment; Stability analysis; Structural stability; Sustainable development; Viability; Waste disposal sites; Waste management; Worms
• ISSN: 2077-0472; 2077-0472
• DOI: 10.3390/agriculture13030547

The improvement of soil fertility properties is a priority for meeting sustainable development goals and world food security. One potential benefit of using paper sludge in agriculture is the reduction of waste and associated environmental impacts. By using paper sludge as a soil amendment, it is possible to divert away this material from landfills and instead use it to improve soil fertility and support the growth of crops. However, it is important to note that paper sludge may contain contaminants harmful to plants and soil health, of which earthworm viability serves as a key indicator. The present investigation aimed to evaluate changes in soil properties after the application of raw and composted de-inking paper sludge for two years. Accordingly, a field study was conducted in Manouba, a semi-arid region of Tunisia with a clay loam soil. The raw de-inking sludge (DS) and composted de-inking paper sludge (DSC) were applied at 30 and 60 t ha−1 and 20 and 40 t ha−1, respectively. Soil treatments were compared to unamended soils (C), to determine the optimal sludge treatment and rate for increasing the soil quality. Soil chemical (soil organic matter SOM, total carbon TC, and nitrogen TN, nutrient soil contents organic matter fractioned), physical (porosity and structural stability), and biological parameters (earthworms viability) were assessed. The results showed an increase of soil OM in the DS and DSC amended soils with the lowest rates (30 and 20 t ha−1). The humic fraction was found to be the dominant form. TC and TN were improved in the DS and DSC amended soils with the highest rates: 60 (DS2) and 40 t ha−1 (DSC2). Phosphorus and potassium were also increased in a dose-dependent manner. However, the soil porosity decreased in all treatments. The composted de-inking sludge was toxic for epigeic species, which could be explained by the use of litter while composting. Overall, the application of DS and DSC at low rates (30 and 20 t ha−1, respectively) might be a promising alternative for improving soil quality and at the same time ensuring the proper management of these wastes.