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Title: Using anion chromatography-pulsed amperometry to meaasure amino compounds in dairy manure-amended soils

item Olk, Daniel - Dan
item Honeycutt, Charles

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/19/2008
Publication Date: 11/14/2008
Citation: Olk, D.C., Fortuna, A., Honeycutt, C.W. 2008. Using anion chromatography-pulsed amperometry to measure amino compounds in dairy manure-amended soils. Soil Science Society of America Journal. 72(6):1711-1720.

Interpretive Summary: Our knowledge is limited regarding the types of nitrogen compounds found in animal manure and how they interact with each type of soil. Therefore, when animal manure is applied to an agricultural field, we cannot accurately predict the rate at which the manure compounds become available as a nitrogen fertilizer to a crop, and so we cannot calculate efficient rates of manure application that would enable healthy crop growth while avoiding excessive nitrogen movement into the soil and water. In this study we found that a new laboratory method for identifying nitrogen compounds can be used to describe the nitrogen compounds in several soils following manure application. As a result, this new method will allow researchers to more accurately describe manure compounds in soil. Benefits to researchers include improved identification of manure nitrogen compounds in different types of soils and better ability to predict the availability of manure nitrogen as a crop fertilizer, which will help crop producers better manage animal manure.

Technical Abstract: Amino acids and amino sugars comprise the bulk of soil N, so information on their chemical forms and cycling patterns should enable better understanding of soil N issues. In this study we evaluated a recently developed analysis for soil amino compounds (19 amino acids, two amino sugars) that consists of methanesulfonic acid extraction, anion chromatography, and pulsed amperometry detection. Soil samples were taken from a 28-d laboratory incubation of nine soils from six U.S. states that were amended with dairy manure slurry at a rate to simulate 300 kg N ha-1. Manuring resulted in enrichment of the soils by nearly all measured amino compounds but to varying degrees. Most manure-associated amino compounds were relatively stable against mineralization during the short-term incubation, with most compounds having decreased modestly in concentration (mean 11%) by the end of the incubation, in contrast to slight increases (mean 3%) for three compounds that are associated with microbial activity and were not overly abundant in the manure: ornithine, glucosamine, and galactosamine. Soil type significantly affected several measurements. Our results illustrated some shortcomings of this analytical approach, but overall we found it a useful analysis. This approach enabled identification of 41 to 43% of total soil N as amino compounds for all soils and treatments, which is comparable to results reported previously for the conventional analysis involving HCl extraction and cation chromatography. Compared to the conventional analysis, this approach might more efficiently extract basic amino acids and less efficiently extract acidic amino acids.