Trend analysis and evaluation of soil temperature in the East and Southeast Region

Soil temperature plays a critical role in regulating numerous physical, chemical, and biological processes within the soil environment. It directly influences seed germination, sprouting, and root development, all of which are fundamental to agricultural productivity. Over the past century, global climate change has also manifested in altered soil temperature patterns. Consequently, the accurate determination and continuous monitoring of soil temperatures have become increasingly important for sustainable agricultural management. This study aims to analyze long-term trends in soil temperatures at varying depths, based on data collected from 25 meteorological stations across Eastern and Southeastern Anatolia, within the Tigris and Euphrates Basin. Monthly average soil temperature values recorded at depths of 5 cm, 10 cm, 20 cm, and 50 cm between 1980 and 2022 were assessed using the Mann-Kendall trend analysis method. The findings revealed a general upward trend in soil temperatures across most stations, although some locations exhibited localized decreasing trends during the summer months. The most pronounced positive trend was observed at a depth of 50 cm in Siirt province during August (Zs=5,818), whereas the most significant negative trend was identified at the same depth and month in Bingöl province (Zs=-4,67). When averaged across all stations, trend values were calculated as 1,318, 1,265, 1,738, and 1,990 for the 5 cm, 10 cm, 20 cm, and 50 cm depths, respectively. These results suggest that rising soil temperatures may substantially impact soil moisture dynamics, organic matter decomposition rates, soil structure, and regional vegetation patterns. In particular, shifts in surface soil temperature (5 cm depth) are likely to influence the agricultural calendar by altering the timing of key crop management practices, such as sowing, irrigation, and harvesting, in the studied regions.