摘要
氮肥施用是影响农田碳源汇的关键因素,定量评估不同氮肥施用下农田土壤呼吸和碳平衡对于保障土壤地力和调控生态环境碳排放均具有重要意义。笔者利用野外管栽模拟和田间定位试验,研究不同施氮水平下玉米生长季农田的土壤呼吸速率动态变化,并在此基础上解析了农田生态系统的碳平衡状况。结果表明:不同氮肥水平下农田玉米生物量(地上部和根系)固定有机碳量为5660.71~8106.00 kg C/hm2;土壤呼吸释放的总碳量为9209.04~16510.40 kg C/hm2之间,裸地微生物呼吸释放的总碳量为2827.36~6951.68 kg C/hm2之间。玉米生长季中根系呼吸量对土壤总呼吸量的贡献分别为57.9%~69.3%之间。在玉米种植条件下,不同生育期的碳平衡发生了显著变化。在拔节期,不同处理下净生态系统生产力(NEP)均为负值,表现为大气CO2的源;在玉米抽雄期和成熟期,不同处理下NEP均为正值,表现为大气CO2的汇,不同施肥水平下碳汇的程度不同。从不同施氮水平来看,NEP值在不同的生育期随施氮水平增加的变化趋势不同,在拔节期提高氮肥的施用水平,NEP值显著低于不施氮处理,在抽雄期和成熟期提高氮肥的施用水平,NEP值高于不施氮处理。
Nitrogen fertilizer application is a key factor that affects agricultural carbon balance, quantitativeassessment of soil respiration and carbon balance under different nitrogen application levels is important toensure soil fertility and control ecological environment carbon emission. In this study, field tube experimentand field location experiment were conducted to explore the dynamic change of soil respiration rate and carbonbalance in agricultural ecosystem under different nitrogen application levels. The results showed that maizebiomass（overground part and root） fixed organic carbon of 5660.71-8106.00 kg C/hm^2; the total carbon releaseamount of soil respiration was 9209.04-16510.40 kg C/hm^2, the total carbon release amount of microbialrespiration was 2827.36-6951.68 kg C/hm^2 in bare land. Root respiration contributed 57.9%-69.3% to thetotal amount of soil respiration in maize growing season. Under maize plant condition, carbon balance ofdifferent growth stages changed significantly during different growth stages. In the jointing stage, net ecosystemproductivity（NEP） was negative under all treatments, which indicated that soil was the source of atmosphericCO2. In the tasseling stage and the mature stage, NEP was positive and the soil presented as the sink ofatmospheric CO2, the degree of carbon sink was different under different fertilization levels. The trend of NEPwas different with the increase of nitrogen application level, NEP in the jointing stage was significantly lowerthan that of CK treatment with the increase of nitrogen application level, however, it was opposite in tasselingstage and mature stage.
出处
《中国农学通报》
2017年第1期89-95,共7页
Chinese Agricultural Science Bulletin
基金
国家自然科学基金委员会面上基金项目"秸秆还田和根系及其分泌物对潮土有机质积累和团聚体形成的协同作用机制"(41471182)
中国科学院战略性先导科技专项课题"土壤-作物系统高效利用氮磷的综合调控原理与技术集成"(XDB15030302)
国家重点研发计划课题"秸秆还田养分高效利用机理"(2016YFD0200107)
关键词
土壤呼吸
碳平衡
氮肥
玉米
soil respiration
carbon balance
nitrogen fertilizer
maize
