Trends in the chemical properties of orchard soils in Gyeong-buk province from 2002 to 2022

Gyeong-buk province is a major fruit-producing region in comprising approximately 30% of the national orchard area.Given the perennial fruit trees, initial soil management is critical.This study analyzed the chemical properties of topsoil and subsoil from 300 orchard sites in Gyeongbuk over a 20-year period (2002 -2022) at 4-year intervals.The results showed that soil pH increased from an average of 5.7 in 2002 to 6.4 in 2018, followed by a slight decline to 6.2 in 2022.Electrical conductivity (EC) remained below 1 -2 dS m -1 at more than 90% of the sites, indicating minimal risk of salt accumulation.Soil organic matter content fluctuated between 24.6 and 37.3 g kg -1 across the sampling years.Available P 2 O 5 concentration increased from 559 mg kg -1 in 2002 to 746 mg kg -1 in 2006, then remained relatively stable between 2010 (562 mg kg -1 ) and 2018 (591 mg kg -1 ), before showing a significant increase to 809.6 mg kg -1 in 2022, suggesting intensified phosphorus fertilization in recent years.Exchangeable Ca showed an increasing trend from 5.4 cmol c kg -1 in 2002 to 8.8 cmol c kg -1 in 2022, while exchangeable Mg also exhibited an increasing trend from 1.52 cmol c kg -1 in 2002 to 2.39 cmol c kg -1 in 2022, both attributed to continuous lime and dolomite applications for pH management.The subsoil exhibited similar trends to the topsoil in most parameters.This study provides fundamental data for orchard research and highlights the necessity of ongoing soil monitoring and nutrient management to ensure sustainable fruit production.