Biochars Induced Changes in the Physicochemical Characteristics of Technosols: Effects of Feedstock and Pyrolysis Temperature

Abstract

Soils in urban areas are anthropized and unfavorable for agricultural practices. Constructed Technosols (TS) are mainly manmade and easily manipulated by mixing different proportions of anthropogenic materials. To achieve this study, twelve types of biochars were produced at 350 and 450 °C, using olives husks (OH), almond shells (AS) and coffee husk (CH) to improve Sandy soil (SS) quality during ten weeks. The main aim of this work was to assess the short-term impact of biochar addition on soil properties. An open-air pot experiment was designed in a pilot scale adding biochars to SS at the rates of 5%. The results showed that the addition of biochars, in the beginning, improved soil Organic matter (OM) and N contents and there were no significant effects on the pH and EC values in all Technosols compared to control (SS). The OM contents and total N remained stable during the incubation for Technosol treated with biochars produced at 350 °C indicating high recalcitrant indices. However, the OM and N contents decreased for the lower recalcitrance materials prepared at 450 °C. The pH values remained stable and EC increased in soil with all biochars. Thus, the use of biochar contributed to soil carbon sequestration and improved OM content in Technosols.