The Study of Lime Soil Reaction Intensity Estimates Based on CaCO3 Content and pH

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the National Natural Science Foundation of China(No.41671216)and the National Science and Technology Basic Work(No.2014FY110200)

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    【Objective】Soil CaCO3 content and pH are two common indices in routine soil analysis, while lime reaction, pH and content of carbonate equivalents are the three important diagnostic indices in the Chinese Soil Taxonomy. However, generally, the determination of soil pH and CaCO3 content needs to be done with the help of experimental instruments in lab, which is rather costly and time consuming; Actually, intensity of lime reaction can be measured in field with titration of 1:3 dilute hydrochloric acid, which is simple, quick and cheap. Moreover, content of CaCO3, pH and intensity of lime reaction are somewhat interrelated. Therefore, if a model of quantitative relationships between soil CaCO3 content, pH and lime reaction intensity can be built up for a specific area, it will no doubt save or spare the time and money needed for determination of soil pH and CaCO3 content in lab, and it will help make tentative determination in the field of what type of calcareous soil in the Chinese Soil Taxonomy. The purpose of this paper is to try to establish such a model.【Method】Correlation analysis and regression analysis were performed of the data of the 110 typical soil profiles investigated during the provincial soil survey of Shanxi Province, including lime reaction intensities determined in the field, and soil pHs, calcium carbonate contents and ESPs (Exchangeable Sodium Percentage) measured in lab of the soil samples from their 426 genetic horizons, for relationship between calcium carbonate content and soil pH, and statistical analysis was for relationships of lime reaction intensity with soil pH and calcium carbonate content.【Result】Results show that in the soil developed from loess parent material in North China with pH <9, content of calcium carbonate is an important factor affecting soil pH, and the optimal relationship between the two fitted with regression accords with an exponential curve, while pH >9 , no significant relationship was observed between the two, but lime reaction intensity could be used as indicator, reflecting to a certain extent or semi-quantitatively a range of pH or content of CaCO3, rather than a precise value. Moreover, from the viewpoint of soil genesis, the content of CaCO3 is of great significance to the study of soil morphology. So if soil pH or CaCO3 is required to define accurately the position of a soil in the Chinese soil Taxonomy (for instance to define whether or not the soil solum is acidic, or has a calcic horizon / calcification, etc.), it is advisable to recommend the use of the more accurate data obtained in lab. In non-alkaline (pH<9.0) soils derived from loess parent material in North China that have foam reaction in the field, soil pH lingers basically in the ranger 8.51±0.49, no matter whether foam reaction intensity or CaCO3 content is high or low. Soil acidity in such a range has little restraint on crop growth. Therefore, if it is considered whether crop growth would be affected from the angle of soil pH or CaCO3 content only, there is no need to have any lab tests to determine accurate pH or CaCO3 content.【Conclusion】It is feasible to realize semi-quantitative estimation of soil CaCO3 content and pH in soils derived from loess parent material in North China by field testing of lime reaction intensity.

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LI Chao, ZHANG Fengrong, ZHANG Tianzhu, WANG Xiuli, JIN Dongsheng. The Study of Lime Soil Reaction Intensity Estimates Based on CaCO3 Content and pH[J]. Acta Pedologica Sinica,2017,54(6):1369-1376.

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  • Received:March 19,2017
  • Revised:June 29,2017
  • Adopted:July 10,2017
  • Online: September 04,2017
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