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翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Ammonia volatilization from urea ： ウィキペディア英語版 Ammonia volatilization from urea Urea (46-0-0) accounts for more than fifty percent of the world’s nitrogenous fertilizers.〔Schwab, G.J. and L.W. Murdock. Nitrogen Transformation Inhibitors and Controlled Release Urea. Extension Report. Lexington, KY: University of Kentucky College of Agriculture, 2005.〕 It is found in granular or prill form, which allows urea to be easily stored, transported and applied in agricultural settings. It is also the cheapest form of granular nitrogen fertilizer. Since urea is not an oxidizer at standard temperature and pressure, it is safer to handle and less of a security risk than other common nitrogen fertilizers, such as ammonium nitrate. ==Breakdown of urea== For plants to absorb nitrogen from urea it must first be broken down: $(NH\_)\_CO\; +\; H\_O\; \backslash stackrel\; NH\_\; +\; H\_NCOOH\; \backslash rightarrow2NH\_\; +\; CO\_$ Urease is a naturally occurring enzyme that catalyzes the hydrolysis of urea to unstable carbamic acid. Rapid decomposition of carbamic acid occurs without enzyme catalysis to form ammonia and carbon dioxide.〔〔Benini, Stefano, Wojciech R. Rypniewski, Keith S. Wilson, Silvia Miletti, Stefano Ciurli, and Stefano Mangani. 1999. A new proposal for urease mechanism based on the crystal structures of the native and inhibited enzyme from Bacilus pasteurii: why urea hydrolysis costs two nickels. Structure 7:205-216.〕 The ammonia will likely escape to the atmosphere unless it reacts with water to form ammonium (NH4+) according to the following reaction: $NH\_\; +\; H\_O\; \backslash rightarrow\; NH^\_\; +\; OH^$ This is important because ammonium is a plant available source of nitrogen while ammonia is not.〔Brady, Nyle C. and Ray R. Weil. The Nature and Properties of Soils. New York: Prentice Hall, 2001.〕 Additionally, the formation of the hydroxide ion may cause soils around the applied urea particle to have a pH around 9.0 which increases ammonia volatilization. This area is also highly toxic due to elevated ammonia concentration for several hours so it is recommended that urea based fertilizers not be applied or banded with planted seed at a rate that exceeds 10–20 kg/ha, depending on the crop species.〔Wells, K.L., L.W. Murdock and H.F. Miller. Urea as a Source of Fertilizer Nitrogen for Crops in Kentucky. Extension Report. Lexington, KY: University of Kentucky College of Agriculture, 1978.〕 It is important that there is adequate moisture because up to thirty percent of the available nitrogen can be lost through atmospheric volatilization within seventy-two hours of application.〔McInnes, K.J., et al. "Field measurements of Ammonia Loss from Surface Applications of Urea Solution to Bare Soil." Agonomy Journal (1986): 192-196.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Ammonia volatilization from urea」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.