Yun-Gi Cho

This study investigates the impact of biochar derived from red pepper by-products on crop growth, soil carbon storage, and agricultural productivity, with a focus on adapting red pepper cultivation to climate change. The experiment was conducted over two years at the Chungcheongnam-do Agricultural Research and Extension Services in South Korea. Biochar was applied at varying rates based on its carbon content (0.0, 2.5, 5.0, 10.0 Mg C ha⁻¹) to evaluate its effects on soil properties and red pepper yield. The biochar, produced using a Top-Lit Updraft (TLUD) gasification system, possessed a carbon content of 68.7% and a high pH of 10.3. The results demonstrated that biochar application significantly enhanced red pepper growth and yield, with the highest total yield observed at the maximum application rate (BC_10.0, 10.0 Mg C ha⁻¹). However, yield efficiency (yield increase per Mg of biochar C) was highest at the lowest application rate (BC_2.5, 2.5 Mg C ha⁻¹). Soil analysis revealed that biochar amendment improved soil pH, electrical conductivity (EC), and total carbon content. Although the standard soil analysis protocol (<2 mm sieving) resulted in an underestimation of soil carbon stock by excluding coarse biochar particles, the persistence of these coarse fractions confirms the high physical stability of the biochar, validating its potential as a long-term carbon sink. These findings provide a scientific basis for optimized biochar application strategies that balance productivity with carbon sequestration.

This study investigates seasonal and interannual variations in agricultural groundwater quality in Chungcheongnam-do, South Korea, from 2021 to 2024 across 20 monitoring sites, including rice paddies (n = 5), upland fields (n = 5), and greenhouse cultivation areas (n = 10). Samples were collected in April and July each year and analyzed for pH, electrical conductivity (EC), NO 3-N, Cl-, major cations (Na + , K + , Ca 2+ , Mg 2+), and heavy metals (Cd, As, Pb). The mean pH values ranged from 6.4 (paddies) to 6.9 (uplands), generally within the acceptable range (6.0-8.5). EC was highest in paddies (0.45 dS m-1), followed by greenhouses (0.41 dS m-1) and uplands (0.28 dS m-1). NO 3-N concentrations were 10.2 mg L-1 in paddies, 9.1 mg L-1 in uplands, and 6.3 mg L-1 in greenhouses-exceeding the national average (5.30-6.68 mg L-1), with 10-20% of paddy and upland sites surpassing the regulatory threshold (20 mg L-1). Cl-concentrations were also elevated-2.3 mg L-1 (paddies), 28.2 mg L-1 (uplands), and 47.0 mg L-1 (greenhouses)-yet remained below the permissible limit. All samples complied with heavy metal standards. Seasonal differences in water quality were statistically insignificant, reflecting the relative stability of groundwater systems. However, declining EC and ionic concentrations in greenhouse areas appear to result from a shift toward hydroponic cultivation. These findings underscore growing concerns about nitrate contamination in paddy regions and highlight the need for targeted nutrient management and region-specific groundwater protection policies.

Pearson correlation matrix among CCME-WQI, key water quality parameters, farmland ratio, and cumulative precipitation across five provinces in Korea.