Application of High Carbon:Nitrogen Material Enhanced the Formation of the Soil A Horizon and Nitrogen Fixation in a Tropical Agricultural Field

作     者：Masato Oda Kenji Tamura Hiroko Nakatsuka Miki Nakata Yukimi Hayashi 

作者机构：Livestock & Environment Japan International Research Center for Agricultural Sciences Tsukuba Japan Faculty of Life and Environmental Sciences University of Tsukuba Tsukuba Japan Graduate School of Life and Environmental Sciences University of Tsukuba Tsukuba Japan Faculty of Life and Environmental Sciences University of Yamanashi Yamanashi Japan Sitio TKM Sao Paulo Brazil 

出 版 物：《Agricultural Sciences》 (农业科学（英文）)

年 卷 期：2014年第5卷第12期

页      面：1172-1181页

学科分类：1002[医学-临床医学] 100214[医学-肿瘤学] 10[医学] 

主　　题：Carbon Food Security Microorganisms Nitrogen Soil Degradation 

摘      要：It is known that cropping causes soil carbon loss, which is a critical issue, especially in tropical agriculture. Nitrogen input generally increases net primary production but does not increase soil carbon content because nitrogen input enhances soil organic carbon mineralization by microorganisms. A farmer conducted a trial in which he applied material with a high carbon:nitrogen (C:N) ratio without additional nitrogen fertilizer, and achieved a higher productivity than that of conventional farms. Based on his results, we conducted a survey to evaluate the effects of high C:N ratio organic material on the productivity, soil profile, microbial activity, and carbon and nitrogen balance of soil. Results demonstrate that high C:N ratio organic material enhanced the formation of the soil A horizon and increased soil carbon and nitrogen content. Approximately, 15 - 20 t·ha-1·crop-1 of fresh waste mushroom bed was applied to 15 crops over 4.5 years, and the total input of carbon and nitrogen were 5014 and 129 g·m-2, respectively. The soil nitrate nitrogen concentration was the same as that of the neighboring forest soil, which was lower than the standard limit for conventional agriculture;however, the average productivity of crops was approximately four times that of the national average. The soil Ap horizon increased in thickness by 7 cm, and aggregates reached a thickness of 29 cm in 4.5 years. The output/input ratios of total soil nitrogen and carbon were approximately 2.68 - 6.00 and 1.30 - 2.35, respectively, indicating that this method will maintain the carbon and nitrogen balance of the system. The observed soil microbial activity was one order of magnitude higher than that of a fallow field. The results indicate that this agricultural method remediates soil degradation, and improves food production.