哈尼梯田氮素持续供应的土壤碳池涨落机制

The paddy rice production in Hani terraces have been sustaining more than one thousand years. The rice production in Hani terraces had a low usage of chemical nitrogen fertilizers, which had sustained to support the local tradition of rice production. With the Hani terrace tourism development and the increase in the intensity of human intervention, whether the old farming civilization can last forever. This is a problem worthy to be discussed. From the point of "carbon pool”, we intend to study Hani terraced fields in such a low amount of the nitrogen and how to maintain one thousand years of nitrogen supply and keep it a durable production system? Therefore, through the field investigation and indoor cultivation and field experiment of biological method, this project is proposed to carry out the following researches: 1) the nitrogen and carbon source supply mechanism in Hani terraced fields; 2) soil carbon pool fluctuations in Hani terraced fields on the response mechanism of nitrogen; 3) the effects of soil carbon pool on Hani terraced fields nitrogen efficient transport mechanisms. .Through revealing the carbon pool fluctuation adjustment of N sustainable supply and ecological mechanisms of nitrogen supply, which will help us to rise the mechanism of Hani terraces N sustainable supply to the entire mountain-water- forest-field-villages systemic circulation of ecological vision. To determine this unique farmland ecosystem carbon and nitrogen cycle. Under today's ecological civilization construction situation, these studies will provide theoretical reference and technical reserves for paddy fields nitrogen sustainable management.

哈尼梯田水稻生产从一千多年前一直持续到现在，哈尼梯田水稻生产中很少施用化学氮肥，但是却持续支持了当地传统的水稻生产，随着哈尼梯田的旅游开发、人为干预强度的增加，这一古老的农耕文明是否可以一直持续下去。这是一个很值得探讨的问题。本研究从“碳池”的视角，研究哈尼梯田在如此低量投入氮素的情况下，是如何维持千百年来的氮素供应，保持这一生产体系历久不衰？为此，本项目通过野外原位监测、调查、室内生物培养、田间试验等手段，拟开展以下研究：1）哈尼梯田氮素和碳素多源补给机制；2）哈尼梯田的土壤碳池涨落对氮素的响应机制；3）哈尼梯田土壤碳池内氮高效持续转运机制。通过揭示其氮素持续供应的生态化和碳池涨落调节与氮素供应机制，有助于将哈尼梯田氮素持续供应的机制上升到整个山水林田村落和人的生态大循环视野下，去审视这一独特的农田生态系统的碳氮循环过程，为现今生态文明建设下稻田氮素可持续管理提供理论借鉴和技术储备。

本项目围绕哈尼梯田在低量投入氮素的情况下，维持千百年来的氮素供应并保持这一生产体系历久不衰的问题，项目组开展了哈尼梯田氮素和碳素多源补给机制；哈尼梯田的土壤碳池涨落对氮素的响应机制；哈尼梯田土壤碳池内氮高效持续转运机制等方向开展研究。.通过研究获得以下重要结果，森林土壤作为一个天然巨大的氮素库为生命系统提供持续不断的氮素营养，人类的活动削弱了土壤氮素持续供应的潜能。梯田增加了土壤氮素供应的可持续性，梯田土壤能够维持相对较高土壤有机质，梯田土壤有相对较低的8.7%矿质态硝态氮占比，在相同的土壤有机碳量情况下，森林土壤能够贮存更多的氮素。梯田土壤既保障了土壤氮素的供应，又减少了氮素流失的资源环境代价和风险。与入村口相比，农田侧边沟处水中的可溶性氮平均浓度最高，为0.57mg/L。哈尼梯田生态系统水中颗粒态氮为出村口处水中的PN平均浓度最高，为0.40mg/L，水稻分蘖前可溶性总氮主要以 NH4+-N为主，占比为64.80%-94.81%。施肥增加田面水中各形态氮1.48%-147.27%。化肥减量施用使田面水氮素浓度降低了15.13%-82.79%。施肥显著提高了稻瘟病率12.59%-31.2%，减产2.62%-15.71%。长期施用有机肥和秸秆还田更有利于土壤由较酸性向弱酸性和中性转变。施肥显著提高了稻稻瘟病发病率，增碳处理秸秆氮素吸收量显著减少了7.52%（Ｐ<0.05），增碳处理秸秆氮素吸收量显著减少。 .本项目研究的科学意义在于揭示了哈尼梯田氮素和碳素多源补给机制；探明了哈尼梯田的土壤碳池涨落对氮素的响应机制；明确了哈尼梯田土壤碳池内氮高效持续转运机制。回答了科学问题：哈尼梯田在低量投入氮素的情况下，是如何维持千百年来的氮素供应并保持这一生产体系历久不衰。哈尼梯田由于人类生活受现代文明的影响，物质和能量的流动规律发生了根本性的改变。如何在现代文明的帮助下，让千年农耕遗产焕发生机。