Soil Science

Skip Navigation LinksHome > January 2012 - Volume 177 - Issue 1 > Soil Phosphorus Forms Related to Extractable Phosphorus in t...
Soil Science:
doi: 10.1097/SS.0b013e31823782da
Technical Article

Soil Phosphorus Forms Related to Extractable Phosphorus in the Everglades Agricultural Area

McCray, James Mabry; Wright, Alan L.; Luo, Yigang; Ji, Shangning

Collapse Box


Abstract: Optimizing P fertilizer recommendations with proper soil testing will reduce overapplication and is vital for reducing P discharge into the Everglades. Soil samples from five Histosols in the Everglades Agricultural Area were analyzed with the objectives of (i) quantifying the forms of soil P and (ii) relating extractable P using water, acetic acid, Bray 2, and Mehlich 3 extractants to these P fractions. The percentages of five P fractions generally increased with increasing recalcitrance in the order of labile P (KCl-Pi), Fe-Al–bound P (NaOH-Pi), humic-fulvic–bound P (NaOH-Po), Ca-Mg–bound P (HCl-Pi), and residual P with the exceptions of two acid soils in which the highest percentage of total P was in the humic-fulvic fraction. Water-extractable P was strongly (P < 0.001, r = 0.97) correlated with labile P, with each measuring greater P with decreasing pH. Acetic acid–extractable P was correlated (P < 0.05) with residual P (r = 0.47) and negatively correlated with Fe-Al–bound P (r = −0.53). This suggests that this extractant recovers more recalcitrant forms of soil P associated with residual P yet is unable to remove P associated with hydroxides of Fe and Al. Bray 2–extractable P included labile P, humic-fulvic P, and some residual P, with possible contribution from Fe-Al–bound P. Mehlich 3 was the only extractant tested that included labile and nonlabile (primarily Fe-Al–bound ) P while excluding residual P, thus deemed to best indicate the plant-available P pool.

© 2012 Lippincott Williams & Wilkins, Inc.




Article Tools


Article Level Metrics

Search for Similar Articles
You may search for similar articles that contain these same keywords or you may modify the keyword list to augment your search.