摘要
【目的】土壤团聚体不仅是土壤结构的重要单元,也是土壤有机碳和氮素固持的重要场所。探究还田秸秆和有机肥中的有机碳和氮素在土壤团聚体中的残留特征,为深刻认识团聚体对外源有机碳和氮素的固持机制及土壤的可持续管理提供依据。【方法】以中国南方典型红壤(C3植物为主的自然植被)为研究对象,设置以下5个处理:(1)对照;(2)低量玉米秸秆添加;(3)高量玉米秸秆添加;(4)低量15N标记有机肥(与处理(2)等碳量);(5)高量15N标记有机肥(与处理(3)等碳量)。采用室内模拟培养试验(恒温恒湿条件下培养300 d),运用13C和15N同位素示踪技术,研究培养后土壤大团聚体(250—2 000μm)、微团聚体(53—250μm)、粉黏粒组分(<53μm)中有机碳和氮含量及其同位素丰度(13C和15N),分析外源碳氮在土壤各团聚体组分的分配比例及残留特征。【结果】培养300 d后,与对照相比,添加秸秆或有机肥显著提高土壤总有机碳和全氮含量(P<0.05),提高幅度随物料添加量增加而增加。低量或高量有机肥添加后土壤及各级团聚体有机碳和氮素含量显著高于等碳量的秸秆处理。与对照相比,秸秆处理显著提高大团聚体(250—2000μm)有机碳和氮的分配比例,其中,高量处理分别提高19.5和22.4个百分点;但该处理显著降低粉黏粒组分(<53μm)有机碳和氮素分配比例,平均降低11.4和12.6个百分点。与对照相比,有机肥处理显著提高微团聚体(53—250μm)有机碳和氮素的分配比例,其中,低量有机肥处理分别提高11.6和8.3个百分点;而显著降粉黏粒组分(<53μm)的有机碳和氮的分配比例,平均降低6.0和9.4个百分点。同位素结果显示,高量或低量秸秆处理各粒级团聚体之间,大团聚体(250—2 000μm)有机碳的δ13C值最高,其次为粉黏粒组分(<53μm),微团聚体(53—250μm)最低。而不同处理之间,高量秸秆处理总土及各粒级团聚体δ13C值明显高于低量秸秆和对照处理,而后两者没有明显差异。高量秸秆处理下,秸秆有机碳残留率为57.6%,其中,大团聚体的秸秆有机碳残留率(25.9%)相当于粉黏粒组分(<53μm)残留率(13.3%)的2倍。添加15N标记的有机肥处理后,来源于有机肥的氮素在土壤中总残留率为77.3%,其中,微团聚体中有机肥氮素残留率为45.2%,相当于大团聚体(10.4%)的4倍以上。【结论】等碳量条件下,有机肥相对于秸秆更有利于土壤碳氮的积累。还田后50%的残留秸秆有机碳在大团聚体内固持,而58%残留的有机肥氮被固定在微团聚体中。
【Objective】 Soil aggregates was not only one of the key structural unit, but also the most important space for soil carbon and nitrogen sequestration. The objective of this study was to explore the retention characteristics of carbon and nitrogen from corn straw and manure amendment in different size soil aggregates, which would be better understanding of the stabilization mechanism of added organic carbon and nitrogen in the aggregate and sustainable soil management.【Method】The treatments was set as follow：（1） Control;（2） straw addition in low rate;（3） straw addition in high rate;（4） manure addition in low rate（with same amount carbon in treatment（2）;（5） manure addition in high rate（with same amount carbon in treatment（3）. With isotope tracer technique of the natural abundance of 13 C and labeled 15 N, typical red soil from southern China（dominated by C3 natural vegetation） was incubated for 300 days indoor on the condition of constant temperature and humidity. The content of organic carbon and nitrogen, isotopic abundance of 15 N and 13 C in bulk soil and different aggregate size fractions were determined to analyze the distribution of added organic carbon in corn straw and nitrogen in manure, as well as the retention rate of carbon and nitrogen, in macro-aggregate（250-2 000 μm）, micro-aggregates（53-250 μm） and silt-clay size fractions（53 μm）. 【Result】 Results showed that, compared with the control, contents of organic carbon and nitrogen were significantly（P0.05） increased after additions of corn straw and manure in red soil after 300-days incubation. It also showed the more amounts of added organic amendments, the higher increments in soil organic carbon and nitrogen content. Compared with the straw addition with same amount of carbon, application of organic manure can significantly increase the content of carbon and nitrogen in different size aggregates. Compared with the Control, the distribution proportion of organic carbon and nitrogen was significantly increased after adding corn straw in macro-aggregate. The proportion of the 1% straw addition treatment was increased by 19.5 and 22.4 percent points, respectively. However, straw treatment significantly reduced the distribution proportion of organic carbon and nitrogen by an average of 11.4 and 10.6 percent points in 53 μm aggregates of straw treatment, respectively. For the manure addition treatment, the distribution proportion of organic carbon and nitrogen was significantly increased by 11.6 and 8.3 percent points in 53-250 μm aggregate, respectively, whereas the distribution proportion of organic carbon and nitrogen was reduced by an average of 6.0 and 9.4 percent points in 53 μm silt-clay fraction, respectively. In the different aggregate size fractions of corn straws treatment, δ13C value of organic carbon in 250-2 000 μm size fractions aggregate was the highest, the second was in the 53 μm fraction, and the lowest is in the 53-250 μm size aggregate fraction. Isotope analysis indicated that, the δ13C value of the corn addition with high rate treatment was relative high than the corn addition with low rate and the Control CK treatments. But there was no significantly different between the corn addition with low rate and the Control treatment. The retention rate of organic carbon from corn straw was 57.6% in the high corn straw addition treatment, of which the retention rate in the large aggregates（25.9%） was equivalent to 2 times of that in the silt-clay size fraction（13.3%）. The nitrogen retention rate from organic manure was averaged as 77.3%, of which the largest proportion of nitrogen was 45.2% in micro-aggregate, was equivalent to 4 times of that in the macro-aggregate（10.4%）.【Conclusion】With the same amount of carbon addition, carbon and nitrogen from manure is more efficient for soil carbon and nitrogen accumulation. There is about 50% of the stabilized carbon derived from added corn straw was sequestrated in macro-aggregates, whereas about 58% of stabilized nitrogen from manure allocated in micro-aggregates.
出处
《中国农业科学》
CAS
CSCD
北大核心
2015年第23期4660-4668,共9页
Scientia Agricultura Sinica
基金
国家自然科学基金(41371247
31360503)
国家公益性行业(农业)科研专项(201203030)
关键词
团聚体组分
有机碳
全氮
分配比例
同位素标记
aggregate fractions
organic carbon
nitrogen
distribution ratio
isotope labeling
