HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Thien, S. J. Articles by Myers, R. Search for Related Content PubMed Articles by Thien, S. J. Articles by Myers, R. Agricola Articles by Thien, S. J. Articles by Myers, R.

Determination of Bioavailable Phosphorus in Soil

Dep. of Agronomy, Throckmorton Hall, Kansas State Univ., Manhattan, KS 66506

* Corresponding author.

ABSTRACT

Available soil P (AP) is usually based on inorganic P (P_i) soil-test levels, a practice that ignores the potential contribution of organic P (P_o) mineralization. Our objective was to develop a P-availability index that included both P_i and P_o dymanics. Fourteen Kansas soils, ranging in bicarbonate-extractable P_i from 1.5 to 21.5 mg P kg^–1, were used. One set of soils was untreated and another enriched with C + N source to raise microbial activities and create a biological sink for P. The treated soil was designated as bioactive. After 7 d of incubation, we measured the quantity of NaHCO₃-extractable P_i, total P (P_t), and inorganic plus microbial P (P_i+m) in both soils and used these data to describe the size of the labile P_o, microbial P (P_m), immobilized P_i (P_immob), potentially mineralizable P_o (P_min), total bioavailable P, and bioavailable P_o pools. Bioactive soils always had less P_i than untreated soils after incubation, probably, because of microbial immobilization. Labile P_o in the bioactive soils averaged 2.4 times greater than in untreated soils. Labile P_o after incubation averaged 2.8 times greater than the P_i level prior to incubation in bioactive soils and remained essentially the same in untreated soils. Clearly, microbial activity enhanced P_o availability, an increase in AP that would not be apparent in soil tests where chemical extractions measure only P_i. We combined the P_i, P_o, and P_m pools to create a bioavailable-P index. This index differed from the typical soil-test P index (preincubation P_i) more for the bioactive soil (r² = 0.50) than for the untreated soil (r² = 0.74). These data suggest this extraction scheme can enhance understanding of the P-supplying power and P nutritional dynamics of certain soils.

Contribution no. 91-343-J from the Kansas Agric. Exp. Stn.

Received for publication March 18, 1991.

This article has been cited by other articles:

				D. H. Goenadi, Siswanto, and Y. Sugiarto Bioactivation of Poorly Soluble Phosphate Rocks with a Phosphorus-Solubilizing Fungus Soil Sci. Soc. Am. J., May 1, 2000; 64(3): 927 - 932. [Abstract] [Full Text]