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| Comparative Study of Different pH Determination Methods for Assessing Soil Acidification in Greenhouse System |
| Received:April 17, 2014 |
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| KeyWord:pH;determination;acidification assessment;greenhouse soil;salt accumulation;secondary salinization |
| Author Name | Affiliation | E-mail | | WANG Ai-hua | Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
University of Chinese Academy of Sciences, Beijing 100049, China | | | DUAN Zeng-qiang | Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | zqduan@issas.ac.cn | | DONG Jin-long | Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
University of Chinese Academy of Sciences, Beijing 100049, China | | | ZHAO Yu | Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | | | TANG Ying | Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
University of Chinese Academy of Sciences, Beijing 100049, China | | | LI Xun | Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | |
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| Abstract: |
| Five methods for pH determination were compared to seek an optimal assessment method of greenhouse soil acidification. Various amounts of KNO3 were added to obtain soils with a series of salinity without introducing foreign H+, while compound fertilizer(N-P2O5-K2O, 15%-15%-15%) was applied to get soils with a series of salinity with foreign H+ inputs. These soils were subjected to incubation in greenhouse for three months. After that, soil pH was determined in distilled water without CO2(pHw), 0.01 mol·L-1 CaCl2 solution[pH(CaCl2)], saturated paste(pHw”), various concentrations of CaCl2 solution equal to salt concentration in field moist soil solution[pH(salt)], and lime potential(pHw-0.5pCa). The pHw, pH(CaCl2), pHw”, pH(salt), and pHw-0.5pCa values dropped by 0.02~1.41, 0~0.06, 0.36~0.64, 0.17~0.74, and 0.07~0.19 unit by KNO3 addition, and by 0.78~2.01, 0.28~1.49, 0.51~1.87, 0.57~1.89, and 0.53~1.56 unit by compound fertilizer addition, respectively. Hence, the pHw method over-estimated net acid addition and acidification in greenhouse systems. pH(CaCl2) and pHw-0.5pCa would be the best methods for assessment of greenhouse soil acidification. |
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