|Kumar, Kuldip - UNIVERSITY OF MINNESOTA|
|Rosen, Carl - UNIVERSITY OF MINNESOTA|
Submitted to: Nitrogen Workshop Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: June 15, 2003
Publication Date: September 21, 2003
Citation: Kumar, K., Rosen, C.J., Russelle, M.P. 2003. A novel approach to regulate nitrogen mineralization in soil [abstract]. In: Controlling N Flows and Losses. 12th Nitrogen Workshop Proceedings, September 21-24, 2003, Exeter, United Kingdom. p. 36. Technical Abstract: Plant availability of various forms of soil organic nitrogen (N) or N added through plant residues and animal manure is regulated by the rate of organic N mineralization by microorganisms and extracellular enzymes. The release of N from these sources needs to match the plant N requirements in order to reduce the risk of environmental impacts, such as nitrate leaching and release of gases like nitrous oxide. In the past there have been few means to alter N mineralization rate of added organic residues other than through tillage management or residue placement. Our hypothesis was that N mineralization rate will be reduced in the presence of protease inhibitors, which are commercially available to fight diseases such as HIV-AIDS. We added commercially available protease inhibitors to soils with and without alfalfa residues. Some protease inhibitors stopped net N mineralization from soil organic matter during the first week and reduced it by up to 91% over 50 days. Most effective was a mixture of protease inhibitors. Reduced N release from alfalfa residues (about 45%) was maintained only by an additional dose of the mixture, indicating that adjustments in initial protease inhibitor application rate and/or duration of activity are needed. Plants have been developed by others to express protease inhibitor genes for insect pest control. These produced concentrations under greenhouse conditions that likely will be effective in the soil. Using either direct protease inhibitor additions or transgenic techniques, it should be possible to exploit this discovery to better synchronize N mineralization with crop N demand.