不同肥力棕壤全氮和微生物量氮对外源玉米残体氮的响应

发布时间：2018-12-10 13:22

【摘要】：以棕壤玉米长期连作定位试验(27a)形成的高低两种肥力水平土壤为研究对象,采用~(15)N标记的玉米植株为试验试材,分别向两种土壤中加入玉米根、茎、叶(共8个处理),采用室内模拟培养与~(15)N同位素示踪技术,旨在弄清玉米根、茎、叶添加后不同肥力土壤全氮含量及微生物量氮的变化规律。结果表明:(1)添加玉米根、茎、叶后低肥力棕壤全氮含量提升幅度分别比高肥力棕壤高5.75%、4.77%和3.75%,外源新氮的贡献率分别比高肥力棕壤高3.54%、3.28%和2.49%,说明不同肥力土壤对玉米残体添加的响应程度不同,低肥力棕壤对外源新氮施入后的响应更敏感,固定能力更强。(2)在添加玉米残体的56d培养时间内,低肥力棕壤中微生物量氮平均增加0.83—0.98倍,高肥力棕壤中微生物量氮平均增加0.87—1.56倍,可以看出不同部位玉米植株添加后均能显著促进土壤微生物量氮的积累,说明外源有机物输入是刺激土壤微生物数量和活性的重要因素,并且在高肥力土壤中刺激作用更加显著。此外,高肥力土壤添加茎和叶处理微生物量氮显著高于根添加处理,但低肥力土壤中根、茎和叶添加处理土壤中微生物量氮之间无显著差异。外源有机氮输入对土壤氮库的贡献与土壤的肥力水平及不同残体部位自身的物质组成特性密切相关。
[Abstract]:Two kinds of soil fertility were studied in brown soil long-term continuous cropping experiment (27a). Maize plants labeled with ~ (15) N were used as experimental materials, maize roots and stems were added to the two soils, respectively. Leaf (8 treatments) were treated with simulated culture and ~ (15) N isotope tracer technique in order to find out the changes of soil total nitrogen content and microbial biomass nitrogen in different fertility soils after adding maize roots, stems and leaves. The results showed that: (1) the total nitrogen content of low fertility brown soil increased by 5.754.77% and 3.75%, respectively, and the contribution rate of exogenous new nitrogen was 3.54% higher than that of high-fertility brown soil, respectively. 3.28% and 2.49%, indicating that the response of different fertility soils to maize residue was different, and the response of low fertility brown soil to exogenous new nitrogen was more sensitive. (2) the microbial biomass nitrogen increased 0.83-0.98 times in low-fertility brown soil and 0.87-1.56 times in high-fertility brown soil. It can be seen that the accumulation of soil microbial biomass nitrogen can be significantly promoted by adding maize plants in different parts, which indicates that exogenous organic matter input is an important factor to stimulate the quantity and activity of soil microorganisms. And the stimulative effect in high fertility soil is more obvious. In addition, microbial biomass nitrogen was significantly higher in high fertility soils than in root addition treatments, but there was no significant difference between root, stem and leaf supplementation treatments in low fertility soils. The contribution of exogenous organic nitrogen input to the soil nitrogen pool is closely related to the soil fertility level and the material composition characteristics of different residues.
【作者单位】：沈阳农业大学土地与环境学院土肥资源高效利用国家工程实验室和农业部东北耕地保育重点实验室;
【基金】：国家自然基金项目(31330011,41671293) 国家重点研发计划项目(2016YFD0200304)
【分类号】：S158;S513

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