生物炭施用对水稻氮肥利用的影响与机制研究

The application of biochar to croplands has attracted international attention because of its agricultural and environmental benefits. Rice is one of the most important staple food crops in China. At present, there have been some studies available on application of biochar in rice production, and the results show that biochar application can affect nitrogen fertilizer use efficiency in rice and consequently influence rice yield. However, the reasons for the effect of biochar application on nitrogen fertilizer use efficiency and the long-term effect of biochar application on nitrogen fertilizer use efficiency in rice are unclear. We plan to carry out a 2-year 4-season 15N tracer microplot field experiment and a 4-year 8-season fixed field experiment to determine the effects of biochar application on related factors of fertilizer nitrogen uptake and utilization by rice, including the fate of fertilizer nitrogen, root morphological and physiological traits, leaf nitrogen metabolism enzyme activities, leaf photosynthetic characteristics as well as physiological nitrogen use efficiency, and to assess the long-term effects of biochar application on soil nitrogen supply characteristics and nitrogen fertilizer use efficiency in rice. It is hoped that the findings from this study will help to understand the approaches and mechanisms of the effect of biochar application on nitrogen fertilizer use efficiency and the effects and mechanisms of long-term biochar application on nitrigen fertilizer use efficiency in rice, and thus providing theoretical guidance for application of biochar in rice production and for efficient nitrogen management in rice.

生物炭施用于农田因具有良好的农业和环境效益而受到了国际社会的广泛关注。水稻是中国最主要的粮食作物之一。前人就生物炭在水稻生产上的应用已开展了一些研究，虽已明确生物炭施用可以通过影响水稻对氮肥的利用来影响水稻的产量，但并不清楚生物炭施用对水稻氮肥利用影响的原因及长期生物炭施用对水稻氮肥利用的影响。本课题拟通过2年4季15N示踪田间微区试验和4年8季大田定位试验，研究生物炭施用对水稻肥料氮吸收利用相关因素（肥料氮去向、根系形态生理特性、叶片氮代谢酶活性、叶片光合生理特性和氮肥生理利用率）的影响和长期生物炭施用对土壤供氮特性和氮肥利用的影响，以期揭示生物炭施用对水稻氮肥利用影响的途径与机制及长期生物炭施用对水稻氮肥利用的影响与机制，进而为生物炭在水稻生产上的应用和水稻氮肥高效管理提供理论依据。

生物炭施用于农田因具有良好的农业和环境效益而受到了国际社会的广泛关注。水稻是中国最主要的粮食作物之一。前人就生物炭在水稻生产上的应用已开展了一些研究，虽已明确生物炭施用可以通过影响水稻对氮肥的利用来影响水稻的产量，但并不清楚生物炭施用对水稻氮肥利用影响的原因及长期生物炭施用对水稻氮肥利用的影响。.为此，本项目通过大田定位试验（2015-2017年早季和晚季）、15N示踪田间微区试验和盆栽试验，研究了生物炭施用（20 t/hm2/季）对水稻氮素吸收的影响与机制、生物炭施用对水稻利用所吸收氮素的影响与机制。.研究表明，连续多季施用生物炭可显著增加水稻对土壤氮的吸收，但同时会显著减少水稻对肥料氮的吸收，且两者的相互补偿使得连续多季施用生物炭对水稻氮素吸收总量无显著影响。连续多季施用生物炭虽然有利于提高土壤全氮含量，但同时会降低土壤转化酶活性，进而对土壤有效氮含量无显著影响。因此，连续多季施用生物炭增加水稻对土壤氮的吸收可能主要与其促进了水稻根系生长有关。连续多季施用生物炭减少水稻对肥料氮的吸收主要与其增加了NH3挥发和土壤对肥料氮的固持有关。其中，NH3挥发的增加与土壤pH上升有关。.研究还表明，连续多季施用生物炭有利提高水稻氮素籽粒生产效率，进而提高水稻的产量。连续多季施用生物炭虽然会导致水稻粒重和结实率下降，但有利于提高单位面积颖花和总生物量，进而促进水稻增产。.项目研究初步明确了施用生物炭对水稻氮素吸收利用的影响及其机制，可为生物炭在水稻生产上的应用和水稻氮肥高效管理提供理论依据。