Rational application of treated sewage sludge with urea increases GHG mitigation opportunities in Mediterranean soils

In the 40 t ha−1 3yr−1 treatment, interesting similarities were found with urea alone. In summary, rational application of TSS, such as 40 t ha−1 3yr−1 dose, along with urea, trigger a beneficial increase in microbial activity in soil, that ultimately activates soil metabolism and enhances carbon sequestration possibilities, while GHG emissions remain at the same level as with urea alone. The results support the hypothesis that TSS can induce carbon sequestration without increasing GHG emissions. TSS has proven to exert beneficial outcomes under Mediterranean conditions; additionally, its application offers a viable opportunity for converting this by-product into a fertilizer. However, application rates must be adjusted or it should be used together with mineral fertilization.