DOI: 10.57760/sciencedb.06975
title: Acidification Resistance of Tobacco-planting Soils with Different Parent Materials in Wuling Qinba District, China
title: 武陵秦巴山区不同母质植烟土壤抗酸化性能研究

description: 【Objective】 This study aimed to investigate the effects of parent materials and initial soil pH on the resistance of soil to acidification. 【Method】 Twelve soil samples derived from different parent materials under tobacco-cultivation were collected from Wuling Qinba District, China. The pH buffering capacity (pHBC) of the different soil samples was determined by acid-base titration in the pH range 4.0 to 7.0. Additionally, the changes of soil pH, soluble Al and exchangeable Al following acid input were investigated through simulated acidification with HNO3. 【Result】 The results showed that soil pHBC was significantly affected by parent materials and initial soil pH. Due to the depletion of buffering substances in soils by acidification, the pHBC of weakly acidic yellow-brown soils and yellow soils (11.79-45.15 mmol·pH-1·kg-1) was lower than that of neutral yellow-brown soils and yellow soils (23.74-141.53 mmol·pH-1·kg-1). Therefore, the decrease in soil pH and increase in soil active Al in neutral yellow-brown and yellow soils was slow during the simulated acidification, indicating a weak acidification potential. Among the neutral yellow-brown soils and yellow soils, the soil pHBC increased with an increase in carbonate content in soils. The soils derived from limestone and carbonate parent materials reserved more carbonate (21.14 and 1.18 g·kg-1), which led to a higher pHBC than soils derived from quartzite and siliceous parents. However, the opposite tendencies were observed in the weak acid yellow-brown soils and yellow soils. In weak acid soils, the exchangeable base cations played the major pH buffering role due to the exhaustion of carbonate. Compared with the soils derived from limestone and carbonate parents, soils derived from quartzite and siliceous parents contained more clay and organic matter, which provided more H+ exchangeable sites and was thus beneficial to buffer exogenous acid and slow down the activation of soil aluminum during acidification. Among the 12 tested soils, the acidic yellow-brown soil derived from pelite was extremely sensitive to exogenous acids due to the lowest pHBC (11.79 mmol·pH-1·kg-1). When 6 mmol·L-1 HNO3 was added, the pH of the acidic yellow-brown soil derived from pelite was lower than that of the acid yellow-brown soils derived from carbonate parents and siliceous parents (by 0.74 and 1.10 pH units, respectively). Correspondingly, the soluble Al and exchangeable Al in the acid yellow-brown soil derived from pelite were significantly higher than those in the acid yellow-brown soils derived from carbonate parents and siliceous parents. 【Conclusion】 The acid yellow-brown soil derived from pelite presented the highest potential acidification risk. Thus, it is necessary to pay more attention to the acidification trend of soils derived from pelite and improve the resistance of these soils to acidification through the application of organic fertilizer. These findings provide significant guidelines for the management of soil acidification during continuous tobacco cultivation in the Wuling Qinba region, China.
description: 【Objective】 This study aimed to investigate the effects of parent materials and initial soil pH on the resistance of soil to acidification. 【Method】 Twelve soil samples derived from different parent materials under tobacco-cultivation were collected from Wuling Qinba District, China. The pH buffering capacity (pHBC) of the different soil samples was determined by acid-base titration in the pH range 4.0 to 7.0. Additionally, the changes of soil pH, soluble Al and exchangeable Al following acid input were investigated through simulated acidification with HNO3. 【Result】 The results showed that soil pHBC was significantly affected by parent materials and initial soil pH. Due to the depletion of buffering substances in soils by acidification, the pHBC of weakly acidic yellow-brown soils and yellow soils (11.79-45.15 mmol·pH-1·kg-1) was lower than that of neutral yellow-brown soils and yellow soils (23.74-141.53 mmol·pH-1·kg-1). Therefore, the decrease in soil pH and increase in soil active Al in neutral yellow-brown and yellow soils was slow during the simulated acidification, indicating a weak acidification potential. Among the neutral yellow-brown soils and yellow soils, the soil pHBC increased with an increase in carbonate content in soils. The soils derived from limestone and carbonate parent materials reserved more carbonate (21.14 and 1.18 g·kg-1), which led to a higher pHBC than soils derived from quartzite and siliceous parents. However, the opposite tendencies were observed in the weak acid yellow-brown soils and yellow soils. In weak acid soils, the exchangeable base cations played the major pH buffering role due to the exhaustion of carbonate. Compared with the soils derived from limestone and carbonate parents, soils derived from quartzite and siliceous parents contained more clay and organic matter, which provided more H+ exchangeable sites and was thus beneficial to buffer exogenous acid and slow down the activation of soil aluminum during acidification. Among the 12 tested soils, the acidic yellow-brown soil derived from pelite was extremely sensitive to exogenous acids due to the lowest pHBC (11.79 mmol·pH-1·kg-1). When 6 mmol·L-1 HNO3 was added, the pH of the acidic yellow-brown soil derived from pelite was lower than that of the acid yellow-brown soils derived from carbonate parents and siliceous parents (by 0.74 and 1.10 pH units, respectively). Correspondingly, the soluble Al and exchangeable Al in the acid yellow-brown soil derived from pelite were significantly higher than those in the acid yellow-brown soils derived from carbonate parents and siliceous parents. 【Conclusion】 The acid yellow-brown soil derived from pelite presented the highest potential acidification risk. Thus, it is necessary to pay more attention to the acidification trend of soils derived from pelite and improve the resistance of these soils to acidification through the application of organic fertilizer. These findings provide significant guidelines for the management of soil acidification during continuous tobacco cultivation in the Wuling Qinba region, China.