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Cuộc sống IS hoạt động chặt chẽ liên quan đến chu kỳ nitơ trên trái đất. Protein là một KHCN trong những thành phần quan trọng của sinh vật, và protein bao gồm axit amin, lần lượt nào Bao gồm carbon, hydro, oxy, và nitơ. Nitơ Constitut khoảng 79% bầu khí quyển. Nitơ này IS phân tử nitơ (N2). Hầu hết các sinh vật, tuy nhiên, có thể không trực tiếp Sử dụng phân tử nitơ. Chỉ có một số loại vi khuẩn tổng hợp protein CDN từ các phân tử nitơ trong không khí. Sinh vật được gọi là luận án nitrogenfixing vi khuẩn. Tỷ lệ. | 920103_CRC20_0904_CH17 1 13 01 11 18 AM ge 351 CHAPTER 17 Nitrogen Cycle and Agriculture Hiroyuki Kawashima Introduction.351 Nitrogen Cycle.353 Global Balance.354 Nitrogen Cycle and Agriculture.357 Nitrogen Fertilizer Input.358 Protein Consumption Rate.358 Food Supply in Japan.359 Nitrogen Cycle in Tokyo Bay.361 N2O and the Nitrogen Cycle.364 Nitrogen Fertilizer Use in the 21st Century.365 How to Reduce Nitrogen Fertilizer Application.367 References. 369 INTRODUCTION Life activity is closely related to the nitrogen cycle on earth. Protein is one of the most important components of organisms and proteins consist of amino acids which in turn consist of carbon hydrogen oxygen and nitrogen. Nitrogen constitutes about 79 of the atmosphere. This nitrogen is molecular nitrogen N2 . Most organisms however cannot directly utilize molecular nitrogen. Only certain kinds of bacteria can synthesize proteins from the molecular nitrogen in the air. These organisms are called nitrogenfixing bacteria. The rate of nitrogen fixation by bacteria is relatively slow compared to other reactions carried out by organisms. Therefore nitrogen is often the restricting factor in plant growth. Agriculture is the industry that cultivates plants and nitrogen is necessary for the growth of these plants. It is necessary to supply arable lands with 0-8493-0904-2 01 0.00 .50 2001 by CRC Press LLC 351 920103_CRC20_0904_CH17 1 13 01 11 18 AM Page 352 352 STRUCTURE AND FUNCTION IN AGROECOSYSTEMS DESIGN AND MANAGEMENT a great deal of nitrogen to produce large harvests. From ancient times supplying farmlands with nitrogen has been a significant problem for mankind. Nitrogen in arable land increases naturally due to nitrogen-fixing microbes. Therefore breaks in cultivation are effective to maintaining plentiful harvests in the same field. Compost has also been used widely throughout the world in order to increase nitrogen concentrations in the soil. In Japan even human excrement has been widely used for .
