Response of Saline and Sandy Soils to Different Soil Amendments: Compost, Biochar, Zeolite and Agricultural Gypsum

Egypt faces a significant food production gap due to land degradation. To bridge this gap, workers in the agricultural sector should maximize the utilization of degraded soils. The reclamation of saline and sandy soils has become a national priority. So, this study was carried out following a completely randomized design (CRD) aiming to evaluate the effectiveness of different soil amendments (compost, biochar, zeolite and agricultural gypsum) in improving the properties of two soil types (saline and sandy). Specifically, the study focused on the impact of the soil amendments on the physical and chemical properties, water retention, leachate characteristics and nutrient dynamics. To achieve this, 60 soil columns were used, as each column was filled with 1000 g of air-dried and sieved soil (≤2 mm), representing one of the two studied soil types (30 for saline and 30 for sandy). Each amendment was mixed with the abovementioned soil additives at a rate of 10% by weight, then each column was irrigated with tap water to achieve saturation. Soil and leachate samples were collected at two key time points (after 20 and 40 days from the beginning of the experiment). All amendments had significant effects on most of the studied characteristics of both soils, and this was also reflected in the leachate characteristics. For example, all the amendments were successful in reducing EC over time except biochar and zeolite amendments. The amendment that had the most pronounced effect was agricultural gypsum, bringing EC down to 7.25 dSm-¹ after 40 days in saline soil. Compost and biochar significantly improved organic matter content compared to other treatments, as zeolite and gypsum had no significant impacts. Biochar and zeolite also improved water retention, achieving final values of 15.3% and 14.8%, respectively in sandy soil. Generally, integrating these amendments into soil management practices can boost agricultural productivity in Egypt’s degraded soils.