Enhancing Soil Fertility in Arid and Semi-Arid Climates Using Leguminous Trees: A Species-Specific Agroforestry Approach

Soil fertility decline is a critical barrier to sustainable agriculture in arid and semi-arid regions. This study evaluated the influence of four native leguminous tree species; Albizia lebbeck, Dalbergia sissoo, Prosopis cineraria and Vachellia nilotica on soil physicochemical properties at four depths (0–15 cm, 15–30 cm, 30–45 cm and 45–60 cm) in Bahawalpur District, Pakistan. A three-year field experiment, using a randomized complete block design, assessed soil pH, bulk density, organic matter, organic carbon, moisture, saturation, electrical conductivity and available N, P and K. Results revealed significant differences (p < 0.05) among tree species and across soil depths. D. sissoo had the highest soil pH (8.26), moisture (19.72%), and saturation (36.77%) at 0–30 cm. V. nilotica showed consistent organic matter and had the highest nitrogen content (11.1 mg/kg), while A. lebbeck contributed the most potassium (109 mg/kg), and D. sissoo led in phosphorus (9.1 mg/kg). P. cineraria and A. lebbeck significantly reduced soil electrical conductivity. Among all species, V. nilotica emerged as the most effective for enhancing soil fertility due to its balanced contributions to nitrogen and organic matter. The findings emphasize the critical role of species selection and depth-specific assessments in designing agroforestry systems aimed at improving soil health and boosting productivity. These findings also provide a robust, evidence-based guide for selecting tree species to integrate into agroforestry systems, offering practical strategies for improving agricultural resilience and smallholder livelihoods in water-scarce environments.

Keywords: Arid; Soil fertility; Agroforestry; Physicochemical; Nitrogen fixing trees.