TITLE:
Removal of Lithium Citrate from H3A for Determination of Plant Available P
AUTHORS:
Richard L. Haney, Elizabeth B. Haney, Douglas R. Smith, Michael J. White
KEYWORDS:
Phosphate, Soil Extraction, Lithium Citrate
JOURNAL NAME:
Open Journal of Soil Science,
Vol.7 No.11,
November
13,
2017
ABSTRACT: The soil extractant, H3A, has undergone several
iterations to extract calcium (Ca), iron (Fe), aluminum (Al), potassium (K),
phosphorus (P), ammonium (NH4-N) and nitrate (NO3-N)
under ambient soil conditions. Few soil extractants currently used by
commercial and university soil testing laboratories can perform multi-nutrient
extraction without over- or under-estimating at least one nutrient. Soil pH and
plant root exudates have a strong influence on nutrient availability and H3A
was developed to mimic soil conditions. Lithium citrate was previously used in
the H3A formulation, but resulted in a cloudy supernatant in some samples,
complicating laboratory analyses. In this study, we removed lithium citrate and
compared the nutrients extracted from the modified (H3A-4) to the established
(H3A-3) solutions. We found that the new extractant, H3A-4, produced a clear
supernatant even in soils with low pH and high iron and aluminum concentrations.
H3A-4 accurately predicts plant available nutrients and is a viable choice for
commercial and laboratory settings due to its ease of use.