Seasonal changes in soil acidity and related properties in ginseng artificial bed soils under a plastic shade

Background: In Changbai Mountains, Panax ginseng (ginseng) was cultivated in a mixture of the humus and albic horizons of albic luvisol in a raised garden with plastic shade. This study aimed to evaluate the impact of ginseng planting on soil characteristics. Methods: The mixed-bed soils were seasonally collected at intervals of 0-5 cm, 5-10 cm, and 10-15 cm for different-aged ginsengs. Soil physico-chemical characteristics were studied using general methods. Aluminum was extracted from the soil solids with NH4Cl (exchangeable Al) and Na-pyrophosphate (organic Al) and was measured with an atomic absorption spectrophotometer. Results: A remarkable decrease in the pH, concentrations of exchangeable calcium, NHZ, total organic carbon (TOC), and organic Al, as well as a pronounced increase in the bulk density were observed in the different-aged ginseng soils from one spring to the next. The decrease in pH in the ginseng soils was positively correlated with the NH4+ (r = 0.463,p < 0.01), exchangeable calcium (r = 0.325,p < 0.01) and TOC (r = 0.292, p < 0.05) concentrations. The NO3- showed remarkable surface accumulation (0-5 cm) in the summer and even more in the autumn but declined considerably the next spring. The exchangeable Al fluctuated from 0.10 mg g(-1) to 0.50 mg g(-1) for dry soils, which was positively correlated with the NO3- (r = 0.401, p < 0.01) and negatively correlated with the TOC (r = -0.329, p < 0.05). The Al saturation varied from 10% to 41% and was higher in the summer and autumn, especially in the 0-5 cm and 5-10 cm layers. Conclusion: Taken together, our study revealed a seasonal shift in soil characteristics in ginseng beds with plastic shade. Copyright (C) 2014, The Korean Society of Ginseng. Published by Elsevier. All rights reserved.