Evaluation of soil chemical properties by land-use type and regional variation in agricultural soils of Chungcheongnam-do

Sustainable agriculture relies on maintaining optimal soil chemical properties, including pH, nutrient availability, and salinity.Although intensive farming and long-term fertilizer application have increased crop yields, these practices often induce nutrient imbalances, particularly elevated N and P levels, which may lead to environmental deterioration.This study evaluated nutrient imbalances in paddy and upland soils across 15 districts in Chungcheongnam-do.A total of 21,003 soil samples were collected from 2022 to 2024 and analyzed for pH, electrical conductivity (EC), organic matter (OM), available phosphorus, and exchangeable cations.Results revealed distinct differences between land-use types.Paddy soils exhibited a lower average pH (6.2), and 62.9% of samples were below the optimal OM range, whereas 49.7% exceeded the recommended level of exchangeable potassium (Ex.K).Elevated EC values in several paddy soils reflected localized salinity accumulation.Upland soils exhibited excessive available phosphate at 536.9 mg kg -1 and elevated exchangeable cations.Strong positive correlations among EC, exchangeable cations, OM, and available phosphate in upland soils highlighted structural nutrient redundancy.These findings demonstrate that nutrient distribution is strongly influenced by land use type and management practices.Implementation of site-specific nutrient prescriptions is therefore essential to optimize fertilizer inputs, improve nutrient use efficiency, and mitigate environmental impacts, thereby supporting precision agriculture and sustainable crop production.