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Pedosphere 20(3): 304--310, 2010
ISSN 1002-0160/CN 32-1315/P
©2010 Soil Science Society of China
Published by Elsevier B.V. and Science Press

Inorganic phosphorus fractions and phosphorus availability in a calcareous soil receiving 21-year superphosphate application

WANG Jun^1,2, LIU Wen-Zhao

¹, MU Han-Feng² and DANG Ting-Hui¹

¹ State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100 (China);
² College of Urban and Environment, Northwest University, Xi'an 710127 (China)

ABSTRACT

A long-term (21-year) field experiment was performed to study the responses of soil inorganic P fractions and P availability to annual fertilizer P application in a calcareous soil on the Loess Plateau of China. Soil Olsen-P contents increased by 3.7, 5.2, 11.2 and 20.6 mg P kg^-1 after 21-year annual fertilizer P application at 20, 39, 59, and 79 kg P ha^-1, respectively. Long-term fertilizer P addition also increased soil total P and inorganic P (Pi) contents significantly. The contents of inorganic P fractions were in the order of Ca₁₀-P > Ca₈-P > Fe-P > Al-P > occluded P > Ca₂-P in the soil receiving annual fertilizer P application. Fertilizer P application increased Ca₈-P, Al-P and Ca₂-P contents as well as their percentages relative to Pi. Pi application increased Fe-P and occluded P contents but nor their percentages. Soil Ca₁₀-P content remained unchanged after fertilizer P application while its percentage relative to Pi declined with increasing fertilizer P rate. All Pi fractions but Ca₁₀-P were correlated with Olsen-P significantly. 90% of variations in Olsen-P could be explained by Pi fractions, and the direct contribution of Ca₈-P was predominant. Long-term annual superphosphate application would facilitate the accumulation of soil Ca₈-P, and thus improve soil P availability.

Key Words: long-term experiment, Olsen-P, path analysis, Loess Plateau

Citation: Wang, J., Liu, W. Z., Mu, H. F. and Dang, T. H. 2010. Inorganic phosphorus fractions and phosphorus availability in a calcareous soil receiving 21-year superphosphate application. Pedosphere. 20(3): 304-310.

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