A Discussion on Mehlich-3 Phosphorus Extraction from the Perspective of Governing Chemical Reactions and Phases: Impact of Soil pH

Chad J. Penn, E. Bryan Rutter, D. Brian Arnall, James Camberato, Mark Williams and Patrick Watkins
Additional contact information
Chad J. Penn: USDA-ARS National Soil Erosion Research Laboratory, West Lafayette, IN 47907, USA
E. Bryan Rutter: Oklahoma State University, Department of Plant and Soil Science, Stillwater, OK 74078, USA
D. Brian Arnall: Oklahoma State University, Department of Plant and Soil Science, Stillwater, OK 74078, USA
James Camberato: Purdue University, Department of Agronomy, West Lafayette, IN 47907, USA
Mark Williams: USDA-ARS National Soil Erosion Research Laboratory, West Lafayette, IN 47907, USA
Patrick Watkins: Oklahoma State University, Department of Plant and Soil Science, Stillwater, OK 74078, USA

Agriculture, 2018, vol. 8, issue 7, 1-20

Abstract: Mehlich-3 (M3) is one of the most common agronomic and environmental phosphorus (P) extractants for determining P fertilizer requirements and the potential for non-point source pollution. Understanding how soil properties impact M3 extractability can improve our ability to properly use this soil test. The objectives of this study were to investigate the impact of soil pH on P extractability by M3 and water in different soils containing equal total P, and to ascertain information about mechanisms of M3-P extraction. Soil pH at four field sites was previously adjusted to a range of approximately 4.5–7.5. Soils (Grant, Dale, Teller, Easpur) were characterized, and P was extracted with M3 and water. Extraction of Mehlich-3 P decreased 40% to 55% with increasing pH, which was potentially due to changing P forms, partial neutralization of extractant pH, and consumption of extractant fluoride (F − ) by non P-containing calcium (Ca) minerals. Water-soluble P (WSP) increased with increasing pH up to pH 6–7. Mehlich-3 P and WSP were not positively correlated except for one soil type. Mehlich-3 P is best utilized with WSP as indicators of quantity and intensity, respectively. Use of M3-P alone at pH < 5.5 may overestimate solubility. Further research should examine the suitability of M3-P at pH > 7.

Keywords: Mehlich-3; phosphorus; soil pH; phosphorus forms; phosphorus solubility; phosphorus extractions; phosphorus testing; soil testing (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2018
References: View complete reference list from CitEc
Citations: View citations in EconPapers (2)

Downloads: (external link)
https://www.mdpi.com/2077-0472/8/7/106/pdf (application/pdf)
https://www.mdpi.com/2077-0472/8/7/106/ (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:gam:jagris:v:8:y:2018:i:7:p:106-:d:155810

Access Statistics for this article

Agriculture is currently edited by Ms. Leda Xuan

More articles in Agriculture from MDPI
Bibliographic data for series maintained by MDPI Indexing Manager ().