红壤双季稻田土壤活性碳、氮周年变化及影响因素  

Annual variation of active carbon and nitrogen contents and the related factors in red paddy soils of subtropical China

作　　者：陈春兰[1,2] 涂成[1,2] 陈安磊[1,2] 侯海军[1,2] 刘波[3] 谢小立[1,2] 魏文学[1,2] 孙志龙 CHEN Chun-lan;TU Cheng;CHEN An-lei;HOU Hai-jun;LIU Bo;XIE Xiao-li;WEI Wen-xue;SUN Zhi-long(Key Laboratory of Agro-ecological Processes in Subtropical Region, Chinese Academy of Sciences, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan 410125, China;Taoyuan Station of Agroecology Research, Chinese Academy of Sciences, Taoyuan, Hunan 415700, China;Agricultural Bureau of Taoyuan County of Hunan Province, Taoyuan, Hunan 415700, China;Huilongpu Integrated Service Center for Agriculture of Ningxiang County, Ningxiang, Hunan 410606, China)

机构地区：[1]中国科学院亚热带农业生态研究所/亚热带农业生态过程重点实验室,湖南长沙410125 [2]中国科学院桃源农业生态试验站,湖南桃源415700 [3]湖南省桃源县农业局,湖南桃源415700 [4]湖南省宁乡县回龙铺镇农业综合服务中心,湖南宁乡410606

出　　处：《植物营养与肥料学报》2018年第2期335-345,共11页Journal of Plant Nutrition and Fertilizers

基　　金：国家自然科学基金项目(31200339);科技部国家重点研发计划项目(2016YFD0200307;2017YFD0301504);科技部国际合作项目(2015DFA90450)资助;杂交水稻国家重点实验室(湖南杂交水稻研究中心)开放课题基金(2016KF07)

摘　　要：【目的】研究红壤稻田土壤活性碳、氮含量及其周年变化和影响因素,为弄清红壤双季稻田土壤活性碳、氮季节变化规律,提高土壤养分利用效率提供理论依据。【方法】以红壤稻田长期定位试验(1990年开始)为对象,选择不施肥(CK)、单施NPK化肥(NPK)和有机物(紫云英、稻草)+NPK化肥(NPKM)三个施肥处理,在早稻、晚稻、休闲期取0—20 cm土样,动态监测稻田土壤几种重要活性碳、氮成分,包括无机态氮(NH_4^+N、NO_3~–-N),可溶性有机碳、氮(DOC、DON)和微生物生物量碳、氮(MBC、MBN)的周年动态变化。【结果】稻田土壤NH_4^+-N含量在早稻期间呈下降状态,晚稻期间变化较平缓,休闲期呈先上升后下降的趋势。土壤无机氮主要以NH_4^+N形式存在,其含量范围为14.9~31.6 mg/kg,其休闲期含量略低于生育期(P>0.05);周年土壤NO_3~–-N含量(<3 mg/kg)远小于NH_4^+N含量,与NH_4^+N含量呈现此消彼长的趋势(P<0.01)。稻田土壤DOC、DON周年变化趋势相似(P<0.01),在生育期呈下降状态,休闲期呈先上升后下降趋势,休闲期土壤DOC、DON含量略低于生育期(P>0.05)。休闲期土壤MBC、MBN含量分别为463~701 mg/kg、31.1~52.4mg/kg,比生育期分别提高25.4%~36.9%和62.8%~125.9%。总体来看,稻田休闲期土壤活性碳(DOC+MBC)、氮(NH_4^+N+NO_3~–-N+DON+MBN)含量高于生育期含量,较生育期增幅分别为10.8%~19.6%、10.3%~34.8%。不同施肥处理结果表明,仅施用化肥(NPK处理)对活性碳、氮影响较小(P>0.05),有机物还田能显著提高水稻生育期和休闲期的土壤活性碳、氮含量(P<0.05),NPKM与CK相比活性碳、氮在水稻生育期分别提高53.8%和81.2%,而在休闲期分别提高了43.5%和63.2%。相关性分析结果表明,稻田休闲期土壤NH_4^+N、DOC、DON含量不仅与土壤SOC、TN含量密切相关(P<0.05或P<0.01),还受温度、水分含量等环境因子影响,如休闲期土壤NH_4^+N含量与5 cm处土壤温度呈极显著负相[Objectives] Active carbon and nitrogen play important roles in soil carbon and nitrogen cycle. This study aimed to determine the difference of active carbon and nitrogen contents in soils affected by fertilization and other factors through the year in the subtropical double-rice region of China.[Methods] A long-term field experiment on reddish paddy soil was conducted. The three treatments were CK （non-fertilizer）, NPK （N, P, and K fertilizer application）, and NPKM （NPK fertilizer, milk vetch and rice straw application）. The characteristics and variation trends of inorganic nitrogen （NH4＋-N and NO3--N）, dissoluble organic carbon and nitrogen （DOC and DON） and microbial biomass carbon and nitrogen （MBC and MBN） in soils were investigated during the rice growing and fallow periods.[Results] The NH4＋-N contents in paddy soils fluctuated in all treatments and showed three general trends：decreased during the early rice stage, stable during late rice period, and increased then decreased during the fallow period. NH4＋-N, the main form of inorganic nitrogen in soils, was in range of 14.9-31.6 mg/kg, and no significant difference was found between the rice growing period and fallow period. The contents of soil NO3--N, less than 3.0 mg/kg, were far lower than those of NH4＋-N contents, and there was a reciprocal relationship between them （P 〈 0.01）. Both of soil DOC and DON had a similar annual variation with a declining trend in the rice growing period and an increasing first and decreasing later trend in the fallow period. The contents of MBC and MBN in soils were 463-701 mg/kg and 31.1-52.4 mg/kg during the non-rice growing period, which were increased by 25.4%-36.9% and 62.8%-125.9%, compared to those in the rice-growing period, respectively. Overall, the total contents of active carbon （DOC ＋ MBC） and nitrogen （NH4＋ -N＋ NO3- -N＋ DON ＋ MBN） in soils in the non-rice growing period were increased by 10.8%-19.6% and 10.3%-34.8%, respectively, compared with those in

关 键 词：红壤稻田 休闲期 无机态氮 可溶性有机碳 可溶性有机氮 微生物量碳 微生物量氮 

分 类 号：S511.42[农业科学—作物学]