تأثير الفحم الحيوي وبعض المخلفات العضوية على بعض خصائص التربة الرملية في منطقة السواوة – بمدينة سرت

Abstract

This study was conducted in 2023 at the laboratories of the Department of Soil and Water, Faculty of Agriculture – Omar Al-Mukhtar University, with the aim of evaluating the effect of different types of biochar and some organic residues on selected chemical properties of sandy soil under incubation conditions. Biochar was produced from two types of organic residues (sawdust and poultry manure) using the slow pyrolysis technique at three different temperatures (300, 400, and 500°C). The study also included imported biochar, raw organic residues (raw sawdust and poultry manure), and a control treatment. Biochar was applied to sandy soil at different application rates (2.5, 5, and 10 g.kg-1 soil), in order to monitor changes in soil chemical properties over an incubation period extending from time zero (before incubation) to ten weeks, with measurements taken at 1, 5, and 10 weeks. The experiment was implemented using a Completely Randomized Design (CRD) with three replicates per treatment. Laboratory analyses included measurements of several chemical soil properties: pH, electrical conductivity (EC), organic matter content (OM), cation exchange capacity (CEC), total nitrogen (N), available phosphorus (P), and exchangeable potassium (K). Results were analyzed using Duncan’s Multiple Range Test at a significance level of 0.05. The results showed significant differences among treatments in their effects on soil chemical properties. Biochar derived from poultry manure at 400 and 500°C and applied at 10 g.kg-1 had the most pronounced positive impact on the studied parameters. It increased the soil pH and reduced acidity, enhanced EC due to the release of soluble salts and cations, and significantly increased organic matter, thereby improving the fertility of sandy soils which are naturally low in organic content. Moreover, cation exchange capacity (CEC) increased significantly with the use of poultry-manure-derived biochar, indicating improved nutrient retention. Levels of nitrogen, phosphorus, and potassium also increased, especially with longer incubation periods. Based on these findings, the study concludes that the type of feedstock, pyrolysis temperature, application rate, and incubation time all play critical roles in determining the effectiveness of biochar in improving the chemical properties of sandy soil.