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Pedosphere 20(3): 293--303, 2010
ISSN 1002-0160/CN 32-1315/P
©2010 Soil Science Society of China
Published by Elsevier B.V. and Science Press

Multivariate statistical analysis of potassium status in agricultural soils in Hamadan, western Iran

M. JALALI

Department of Soil Science, College of Agriculture, Bu-Ali Sina University, Hamadan (Iran)

ABSTRACT

Multivariate statistical technique was used to determine the potassium (K⁺) status and to assess soil fertility and K leaching potential in some calcareous soils. Water-soluble K⁺ (H₂O-K) and ammonium acetate-extractable K⁺ (NH₄OAc-K) ranged from 0.019 to 0.590 (mean value 0.095) and 0.390 to 3.320 (mean value 0.954) cmolc kg^-1, respectively. The nitric acid-extractable K⁺ (HNO₃-K) varied from 1.03 to 13.63 (mean value 5.37) cmol_c kg^-1. The proportion of H₂O-K ranged from 0.34% to 14.8% of HNO₃-K, and 2.2% to 53.2% of NH₄OAc-K. The proportion of NH₄OAc-K ranged from 5.8% to 80% of HNO₃-K (mean value 23% of HNO₃-K). The tendency of the soil to lose K⁺ by leaching was examined by determining K⁺-Ca²⁺ exchange isotherms. The soils mostly had moderate to high values of K⁺ sorption capacity, ranging from 10% to 58% (mean value 28%) of added K⁺. The Gapon coefficient varied widely from 1.1 to 12.0 (L mol^-1)^-1/2. Clay minerals were dominated by illite, smectites and vermiculite with small amounts of kaolinite. Principal component analysis (PCA) showed that the first four components accounted for 27.7%, 21.4%, 13.8%, and 8.9% of total variation, respectively. The non-hierarchical cluster analysis (k-means clustering) grouped 75 sampling sites into six clusters, based on the similarity of soil quality characteristics. The results suggested that such classes could form a basis for variable-rate application to maintain an adequate K⁺ status for crop production and to reduce potential K⁺ loss from soil by leaching.

Key Words: adsorption, Gapon coefficient, leaching, non-exchangeable potassium, principal component analysis

Citation: Jalali, M. 2010. Multivariate statistical analysis of potassium status in agricultural soils in Hamadan, western Iran. Pedosphere. 20(3): 293-303.

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