Detection of free amino acids using paper chromatography for evaluating degree of compost maturity
1999
Hara, M. (Mie-ken. Agricultural Technical Center, Ureshino (Japan)) | Hirose, K. | Ishikawa, H.
In order to evaluate the maturity of swine waste compost, we have developed a convenient method for measuring free amino acid levels by paper chromatography. 1) The change of free amino acid in swine waste content with composting was studied using HPLC. The free amino acid content increased for the first several days, and thereafter decreased rapidly to 1/20 of the initial content after four weeks. The change in free amino acid content corresponded to that of easily decomposable nitrogen mineralized by autoclaving. 2) A negative correlation was observed between free amino acid content and the length of Komatsuna (Brassica campestris L.) root in a germination test. The growth inhibition disappeared when the free amino acids decreased and were in equilibria. Free amino acid content can be regarded as an index of compost maturity. 3) Using paper chromatography, the change in free amino acid content could be detected even at a low concentration level. Paper chromatography can be used as a simple method for evaluating free amino acid, reflecting the compost maturity. 4) The evaluation method for compost maturity by paper chromatography is as follow: The milled compost sample is suspended in water (1 : 5 w/v) and left to stand overnight. After filtration, 25 muL of the water extract of the compost is spotted on filter paper, developed with n-butanol: acetic acid : water (12 : 3 : 5), and dried. It is then sprayed with ninhydrin solution, and the bands of amino acids are checked after 5 h when the color becomes stable. When the bands over Rf 0.3 cannot be detected, we cat regard it as a matured compost
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