The effects of water harvesting on the soil of a semi-arid afforestation site in Western Türkiye

Water harvesting techniques effectively improve vegetation establishment in semi-arid environments. This study assessed the effects of site preparation and planting treatments—negarim microcatchments, crescent bunds, burror terraces, pit-planting, and an untreated control—on soil physical and chemical properties and macro- and micronutrient levels three years after treatment. The experiment was conducted at five semi-arid afforestation sites in Izmir, Türkiye. One-year-old stone pine ( Pinus pinea L.) seedlings were planted using a randomized complete block design with five replications. Soil samples were collected from each experimental unit at a depth of 0–30 cm. The pit-planting treatment had the lowest soil bulk density. Soil organic matter (OM) was highest under undisturbed control. Conversely, intensive mechanical treatments (burror terraces and negarim microcatchments) showed 62–64% lower OM amounts than the control. Total N was highest under the control and crescent bunds (0.16% and 0.14%, respectively) and significantly greater than under burror terraces. However, soil texture, pH, electrical conductivity, calcium carbonate, and the carbon-to-nitrogen ratio did not differ significantly. Similarly, available macro- and micronutrients, except for total N, were not significantly affected. Crescent bunds proved as effective as the control in preserving soil OM and N while causing less mechanical soil disturbance. These findings highlight the critical need to understand the mechanisms underlying successful afforestation and site restoration to guide future restoration efforts and policy decisions. From a management perspective, crescent bunds offer the most balanced approach for dryland afforestation, combining hydrological benefits with minimal soil degradation.