Efficient Eco-Friendly Organic Wastes Mixed with Growth Promoting Bacteria to Remediate and Increase Fertility of Saline Sodic Soil in Egypt

Abstract. In Egypt, the total area of agricultural land is 3.36 million acres, which is 3.8 % of the entire territory of the country. One of the main obstacles to agricultural production in Egypt is soil salinization and degradation. Therefore, saline-sodic soil reclamation in arid regions is highly relevant. This study aimed to use Azospirillum inoculation with eco-friendly organic wastes for free remediation of saline-sodic soils. In this work nine treatments included two levels of spent grain (S1 and S2), two levels of compost (C1 and C2), a mix of both sources (C1S1), one level of Azospirillum (A1), a mix of both sources with Azospirillum (A1S1 and A1C1) and an untreated control. The treatments were previously incubated with soil at field capacity for five months under laboratory conditions at 28 °C. The most relevant chemical and biological parameters were analysed every month for five months. Results indicate that Azospirillum inoculation with spent grain increased soil organic carbon (SOC), dehydrogenase and urease enzymes, micro-nutrients (Fe²⁺, Zn²⁺, Mn²⁺, Cu²⁺ and B⁺), and macro-nutrients (N, P and K); while decreased exchangeable sodium percentage (ESP), pH and EC, by 75 %, 12 %, and 43 % respectively, compared to initial conditions. The significant variation was observed in chemical and biological properties among all treatments in the order of S2 > A1S1 > A1 > C2 > C1S1 > A1C1 > C1 > control. In conclusion, the addition of Azospirillum with spent grain is highly recommended for amelioration of the saline-sodic soil and is more effective compared with compost to remediate saline-sodic soils.