Mineralization of amino acids and its signs in nitrogen cycling of forest soil

Amino acid mineralization and its fate in soil have effects on soil nitrogen cycling. Here we used 15N-labeled alanine and methionine to study differences in their mineralization from soil organic nitrogen under 60% WHC (water holding capacity) and 90% WHC soil conditions. We found that the maximum mineralization rates were at the 24th hours for alanine and at the 5th hours for methionine, and about two times greater rates at 60% WHC than at 90% WHC. The half-live was 24-72 h for alanine and > 72 h for methionine. Half-lives of amino acids occurred sooner under 90% WHC than under 60% WHC. The results suggested that some kind of amino acids do lead the nitrogen cycling in a specific ecosystem or as a sign to trigger soil nitrogen cycling when land utilization was altered or disturbed severely by humans.