Carbon cycle and carbon efficiency of farmland ecosystems in Quzhou,Hebei Province
YINYuying1,2,, HAOJinmin1,2,, NIULing’an1,2, CHENLi1,2 1. College of Resources and Environmental Sciences,China Agricultural University,Beijing 100193,China2. Key Laboratory for Agricultural Land Quality Monitoring and Control,The Ministry of Land and Resources,Beijing 100193,China 通讯作者:通讯作者:郝晋珉,E-mail:jmhao@cau.edu.cn 收稿日期:2015-12-10 修回日期:2016-03-8 网络出版日期:2016-05-25 版权声明:2016《资源科学》编辑部《资源科学》编辑部 基金资助:国家科技支撑计划项目:“环渤海经济区基本农田建设技术研究与示范”(2015BAD06B01) 作者简介: -->作者简介:尹钰莹,女,吉林珲春人,硕士生,研究方向为土地利用规划。E-mail:yinyy824@hotmail.com
关键词:农田生态系统;碳循环;碳排放系数;碳效率;曲周县 Abstract Given the vital role that farmland ecosystems play in the global carbon cycle,it is of great significance to study carbon cycles and the regional balance of carbon. Studies of this nature contribute to diversity and providing references when developing low-carbon agriculture and establishing eco-compensation systems. We comprehensively analyzed farmland ecosystem carbon cycles and corrected some carbon emission coefficients based on actual conditions. From the perspective of carbon input,carbon output and fixed carbon,parameters for carbon source/sink and carbon efficiency were calculated. Results show that the carbon balance value of farmland ecosystems was -3.30×104t and the carbon was fixed at a level of 17.61×104t in 2011. Soil respiration and some human productive activities including utilization of nitrogen fertilizer,farm machinery and phosphate fertilizer were the main factors in carbon emission. When analyzing the condition of carbon source in each township in Quzhou,we found that during low output and high input,the farmland ecosystem of Quzhou appeared as a carbon source. On the contrary,the farmland ecosystem of Houcun,Henan Tuan and other towns were a carbon sink on account of low input and high output. In conclusion,farmland ecosystems in Quzhou country show remarkable carbon sequestration capacity and relatively high carbon efficiency,despite the overall performance of a carbon source. To some extent,this can function as compensation for some of the negative effects of carbon emissions on the environment.
(1)对比分析曲周县各乡镇碳源与碳汇系统发现,投入与产出比存在巨大差异。曲周县农户生产过程中氮肥和磷肥施用量过大,土壤中氮素和磷素的平衡值有盈余,普遍超过作物生长的实际需求。不同施肥处理方式下,农田生态系统碳平衡情况会发生变化。黄晶等研究表明无机肥配施有机肥的方式会促进农田生态系统具有较强的碳“汇”功能[41];郭胜利等认为较低的有机物质投入量是制约农田土壤碳储蓄的主要因素,大量施用有机肥是提高农田生态系统固碳量的重要途径[42]。结合曲周县农业生产现状,若通过采用改善施肥条件、精准配比施肥、无机肥配施有机肥、改良作物种子等有效技术措施,提高曲周镇等乡镇的投入产出比,施肥过程中减少碳排放量,同时提高作物产量以增加系统固碳量,曲周县农田生态系统将有很大可能性转变为碳汇系统,提高碳积蓄量大有潜力。 (2)从两个角度探索降低农田生产活动排碳量的途径。从农户生产环节减排,在农资产品使用过程中减少排碳量、将各项生产措施控制在合理程度是减少碳排的有效手段。应加强对各项生产措施合理程度的探索,寻求保证粮食产量的同时低碳生产的方式;从农资投入品供应链源头上减排。农资的生产运输以及化石能源的消耗产生了巨大碳排量,应寻找清洁绿色能源代替化石能源,提高生产农业生产资料的效率,降低生产能耗,在生产及使用环节减少碳排。 (3)当前对农田生态系统碳循环的研究中存在系统边界模糊、核算指标不完整、参数不符合实际等问题。本文在研究过程中明确了系统边界,农田生态系统当年的碳输入及碳输出即在当年确认,确保了研究时间范围的一致性。研究根据曲周县实际情况,对生产活动投入品的碳系数进行修正核算,使研究更符合曲周县实际,结果更加精准。进行作物固碳以及碳移出核算时,作物经济系数等参数随着气候、土壤、种植技术等因素的不同会有一定差异,但目前少有关于作物在不同地区的经济系数等参数的研究,尤其是对棉花的研究更为少见,获取研究区范围内相关参数数值难度较大。根据已有研究,全国小麦和玉米的经济系数范围分别在0.38~0.59以及0.38~0.60[43],各省平均值相差不大。本文在参数选取过程中参考了已有相关文献的引用,选取了相关文献中广泛引用的数值[5,44,45],在一定程度上可以代表曲周县农作物的实际情况。本文虽然在碳排放系数方面做了些改进,但对于农用机械、灌溉等生产投入的碳排放系数计算,由于情况复杂,并未考虑制造机械、建造设备等前期活动的碳耗,这部分排碳量比实际偏小。此外,曲周县土壤呼吸排碳量采用定位试验获得,以点带面概括了曲周全县,对于县域内土壤环境、水分等因素存在差异的地区,土壤呼吸排碳量可再进一步测定。以上问题在今后的研究中,还有待进一步完善。 The authors have declared that no competing interests exist.
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