Application of Kinetic Models in Describing Soil Potassium Release Characteristics and Their Correlations with Potassium Extracted by Chemical Methods

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• 作者：A.R. HOSSEINPUR ; H.R. MOTAGHIAN
• 关键词：chemical extraction ; calcareous soils ; mathematical modeling ; release rate constant ; time segments
• 刊名：Pedosphere
• 出版年：2013
• 出版时间：August, 2013
• 年：2013
• 卷：23
• 期：4
• 页码：482-492
• 全文大小：316 K

文摘

Potassium (K) release characteristics in soil play a significant role in supplying available K. Information on K-release characteristics in soils of central Iran is limited. The objectives of this study were to determine K release characteristics and correlations of K release rate constants with K extracted by different chemical methods in surface soils of ten calcareous soils of central Iran. The kinetics of K release in the soils was determined by successive extraction with 0.01 mol L^?1 CaCl₂ in a period of 2-2 017 h at 25¡À1 ¡ãC. Soil K was extracted by distilled water, 0.5 mol L^?1 MgNO₃, 0.002 mol L^?1 SrCl₂, 0.1 mol L^?1 BaCl₂, 0.01 mol L^?1 CaCl₂, 1 mol L^?1 NaCl, 1 mol L^?1 boiling HNO₃, 1 mol L^?1 NH₄OAC, Mehlich 1, 0.002 mol L^?1 SrCl₂ + 0.05 mol L^?1 citric acid, and ammonium bicarbonate-diethylenetriamine pentaacetic acid (AB-DTPA). A plot of cumulative amounts of K released showed a discontinuity in slope at 168 h. Thus, two equations were applied to two segments of the total reaction time (2-168 and 168-2 017 h). Cumulative amounts of K released ranged from 55 to 299 mg kg^?1 in 2-168 h and from 44 to 119 mg kg^?1 in 168-2 017 h. Release kinetics of K in the two time segments conformed fairly well to parabolic diffusion, simplified Elovich, and power function models. There was a wide variation in the K release rate constants. Increasingly higher average concentrations of soil K were extracted by distilled water, Mehlich 1, SrCl₂, CaCl₂, SrCl₂ + citric acid, AB-DTPA, MgNO₃, NaCl, NH₄OAc, BaCl₂, and HNO₃. Potassium release rate constants were significantly correlated with K extracted. The results of this study showed that information obtained from mathematical modeling in two reaction time segments can help to estimate the K-supplying power of soils.