摘要
为探究长期施用氮肥和秸秆还田措施下农田土壤总有机碳(TOC)的稳定性,以辽宁省国家农业环境阜新观测实验站连续8 a施肥的定位试验田为研究对象,采用有机质酸碱提取和密度分级实验、金属氧化物形态提取实验、碳14定年和次氯酸钠氧化实验等手段,系统研究了长期施用氮肥和秸秆下农田土壤TOC的含量、化学组成及其年龄特征。结果表明:相对于对照组(不施氮肥),单施氮肥处理组的TOC含量降低了5.5%,而氮肥配施秸秆组则升高了2.8%,但两个处理土壤碳氮比均高于对照。随着氮肥和秸秆的加入,土壤有机质酸碱可提取部分的总占比降低,其中胡敏酸从63.6%降低到49.5%,酸碱不可提取部分(即胡敏素)的占比升高(25.9%~39.0%);各处理间土壤TOC的轻、重组分级没有显著差异,均以重组有机碳为主要成分,占TOC的62.3%±0.4%。同时,重组分中可提取的碳和铁铝的比值非常低,表明重组分里的土壤有机质除了与铁铝氧化物结合之外,很可能大部分以团聚或者包被的形式与黏土结合。碳14定年结果显示,3个处理组中土壤的年龄在距今2000 a左右,试验区农田土壤以长期稳定有机碳为主。研究表明,氮肥施用和秸秆还田向土壤中增加新有机碳,增加了土壤中矿质结合的胡敏素类有机质;而所产生的激发效应导致土壤中部分原有的稳定有机碳降解,减少了腐植酸类有机质。新增有机碳的不稳定性及激发效应导致的原有稳定有机碳的降解,制约了氮肥施用和秸秆还田对土壤TOC累积的贡献。
In this study,the effects of nitrogen(N)fertilization and straw returning on the content,fractions and stability of soil total organic carbon(TOC)were investigated.Soil samples were taken from Fuxin Agricultural Environment and Farmland Conservation Scientific Observatory Experimental Station in Liaoning Province,China,where the treatments were continuously maintained for eight years.The soil samples were analyzed using methods such as acid-base extraction,density separation,metal hydroxide extraction,14C dating,and chemical oxidation.The results showed that,in comparison with the control,apply only N fertilization(N1)decreased TOC content by 5.5%,whereas N fertilization in combination with straw returning(NS)increased TOC content by 2.8%.In both the N1 and NS treatment,the carbon and nitrogen ratio was higher than that of the control.Upon N1 and NS,the fraction of acid-base extractable soil organic carbon(SOC)decreased,in which the fraction of humic acid(HA)decreased from 63.6% to 49.5%.Correspondingly,the acid-base nonextractable humin fraction increased by 25.9%-39.0%.There was no significant difference in the proportion of the light and heavy fraction of SOC between treatments.The heavy fraction was dominant,accounting for 62.3%±0.4% of TOC.The ratios of extractable C to Fe and Al was very low,indicating that,besides oxides bound to Fe and Al,most SOC in the heavy fraction was associated with clay as coagulates and coating.14C dating showed that the average age of TOC in these soils was around 2000 years old.Overall,the long-term stable SOC dominated in these soils.Due to the addition of new organic carbon,the application of N and straw increased the mineral-associated humin-like SOC.However,because of the priming effect,a fraction of original stable SOC was decomposed,leading to a decrease of fulvic acid-like SOC.The instability of newly added organic carbon and the degradation of stable SOC stimulated by the priming effect limited the contribution of N1 and NS to TOC accumulation.
作者
黄磊
张然
陈雅丽
牛翠云
翁莉萍
马杰
李永涛
张哲
HUANG Lei;ZHANG Ran;CHEN Yali;NIU Cuiyun;WENG Liping;MA Jie;LI Yongtao;ZHANG Zhe(Agro-Environmental Protection Institute,Ministry of Agriculture and Rural Affairs,Tianjin 300191,China;College of Natural Resources and Environment,South China Agricultural University,Guangzhou 510642,China;Liaoning Academy of Agricultural Sciences/Fuxin Agricultural Environment and Farmland Conservation Scientific Observation Experimental Station,Fuxin 123100,China)
出处
《农业环境科学学报》
CAS
CSCD
北大核心
2024年第3期581-589,共9页
Journal of Agro-Environment Science
基金
天津市自然科学基金项目(22JCYBJC00490)
农业基础性长期性科技工作国家农业环境数据中心观测监测任务(NAES034AE02)。
关键词
氮肥
秸秆
褐土
稳定性有机碳
nitrogen fertilizer
straw
cinnamon soil
stable organic carbon
