长期施肥对灰漠土团聚体形成及有机碳固存影响机制研究

发布时间：2018-03-23 01:18

本文选题：长期施肥　切入点：灰漠土　出处：《新疆农业大学》2016年博士论文　论文类型：学位论文

【摘要】：灰漠土是我国西北干旱地区具有代表性的一类农田土壤,近年来受植被退化、生物多样性减少的影响,灰漠土的土壤结构遭到严重破坏,致使土壤肥力大幅下降,严重制约新疆灰漠土区农田持续高产和稳产。为了增强土壤结构性、提高土壤生物多样性,本研究选择位于西北干旱荒漠地带性土壤-灰漠土为基础,利用“国家灰漠土肥力与肥料效益监测站”长期定位肥料试验区中的6个处理:1)不耕作、不施肥(撂荒,CK0);2)不施肥(CK);3)单施氮肥(N);4)氮磷钾配施(NPK);5)氮磷钾+增量有机肥(1.5MNPK);6)氮磷钾+秸秆还田(SNPK),研究了灰漠土区不同肥料长期定位配施过程中,土壤团聚体的形成及团聚体结合有机碳的化学组成、土壤动物群落结构和多样性与团聚体的相关性、团聚体有机碳组分时间序列上的变化特征,同时分析不同有机碳组分与土壤肥力的关系;进而阐明团聚体组成对有机碳的物理化学保护作用,明确了灰漠土团聚体的形成及有机碳的固存机制,为提高灰漠土区农田生产力,实现区域农业可持续发展提供理论基础与实践依据。研究结果说明,在灰漠土区大团聚体和粉粒+粘粒组分对施肥措施的响应更加敏感,而土壤有机碳趋向微团聚体累积有益于土壤有机碳的长期固存。增施有机肥通过保护团聚体内颗粒态有机碳(Particulate organic carbon,POC)和提升了大团聚体的质量分数,促进了土壤的团聚化程度,利于土壤结构的改善,进而提高了土壤有机碳含量,而且增施有机肥(1.5MNPK)的效果比秸秆还田(SNPK)更明显。而单独施用化肥仅仅能够维持土壤有机碳含量,对提升土壤的团聚化程度并没有产生显著的影响。由此可见,在团聚体的形成过程中,有机质起了非常重要的胶结作用,能够促进大团聚体的形成,进而提高团聚体的稳定性,有利于土壤肥力的改善。利用核磁共振波谱技术研究了土壤和各粒级团聚体中有机碳的分子结构特征,结果显示随着团聚体粒级逐渐减小,烷基碳与羰基碳的比例逐渐增加,烷氧碳与芳香碳的比例逐渐减小,烷基碳/烷氧碳的比率逐渐升高,有机质的分解程度不断增加。与不施肥土壤相比较,长期有机-无机配合施用(1.5MNPK和SNPK)提高了土壤有机质中烷氧碳和羰基碳的比例,羰基碳的累积主要发生在大团聚体和微团聚体中。长期单独施用化肥(N和NPK)土壤中烷基碳的比例明显增加,芳香碳和羰基碳的比例明显减小,增大了烷基碳/烷氧碳的比率,加速了有机质的矿化分解。表明长期施用有机肥带入大量的碳水化合物和有机酸,通过大团聚体和微团聚体对有机碳的化学保护来增强土壤有机质的稳定性,从而提高土壤有机碳含量。土壤动物群落的分布与不同肥料的性质紧密相关。增施有机物料(1.5MNPK和SNPK)有利于土壤动物生存,能够持续性地增加土壤动物群落的个体总数和总类群数,而平衡施用化肥(NPK)仅能够增强土壤动物群落的丰富度。土壤动物群落总个体数及多样性指数(H’)与粉粒+粘粒组分和大团聚体结合有机碳含量及大团聚体的质量分数均存在显著的正相关性,说明团聚体为土壤动物群落提供了丰富的营养能量来源,同时土壤动物群落的多样性也促进了土壤的团聚化程度。24年连续长期配施有机肥(1.5MNPK),灰漠土中总有机碳及其组分随施肥时间延长而显著增加,其中砂粒结合有机碳组分对施肥措施的响应更加敏感,增加幅度最大,对土壤总有机碳累积的影响要高于其它组分。轻质有机质(粗自由颗粒态有机碳和细自由颗粒态有机碳)组分对土壤养分变化的响应更加积极,而存在于微团聚体中的物理保护性有机碳组分对土壤养分的供应和土壤总有机碳的固存起着置关重要的作用。
[Abstract]:Grey desert soil is a kind of soil in the arid area of Northwest China representative, in recent years by the impact of vegetation degradation, biodiversity loss, severe destruction of soil structure in grey desert soil, the soil fertility declined sharply, seriously restrict the farmland in Xinjiang gray desert soil zone of sustainable production. In order to improve soil structure, improve soil biodiversity, this study is located in the northwest arid desert zone of soil and grey desert soil as the basis, using the "6 national grey desert soil fertility and fertilizer efficiency monitoring station" in a long-term fertilization experiment: 1) no tillage, no fertilizer (fallow, CK0) 2) not; fertilization (CK); 3) n (N); 4) nitrogen phosphorus and potassium (NPK); 5) NPK + organic fertilizer increment (1.5MNPK); 6) NPK + straw (SNPK), studied the effect of fertilizer grey desert soil long-term positioning fertilization process in the formation of soil aggregates and aggregate According to the chemical composition of organic carbon, the correlation between soil animal community structure and diversity and aggregates, aggregate organic carbon fractions change characteristics of time series, and different organic carbon fractions and soil fertility relationship analysis; and then clarify the aggregate physical and chemical protective effect on organic carbon sequestration, the formation mechanism of ash desert soil aggregates and organic carbon, in order to improve the farmland grey desert soil productivity, realize the sustainable development of regional agriculture provide a theoretical basis and practical basis. The research results show that in large aggregates of grey desert soil and silt + clay fraction in response to fertilization is more sensitive, and soil organic carbon accumulation Trend Micro aggregates beneficial to soil organic carbon sequestration. The long-term application of organic fertilizer by protecting the agglomerates of particulate organic carbon (Particulate organic carbon, POC) and enhance the quality of the reunion Scores, promoted the aggregation degree of soil, conducive to the improvement of soil structure, and increase the content of soil organic carbon, and organic fertilizer (1.5MNPK) effect than straw (SNPK) is more obvious. And the application of chemical fertilizer can only maintain soil organic carbon content, the degree of agglomeration and enhance soil have a significant impact. Thus, in the process of the formation of aggregates, organic matter plays a very important role in cementing, can promote the formation of large aggregates, thus improving aggregate stability, conducive to improving soil fertility. To study the molecular structure characteristics of soil organic carbon and various aggregates using NMR techniques the results show, with the aggregate particle decreases, alkyl carbon and carbonyl carbon increased, alkoxy carbon and aromatic carbon ratio decreased, the ratio of alkyl alkoxy carbon / carbon Gradually, the degree of decomposition of organic matter increased. Compared with no fertilization soil, long-term combined application of organic and inorganic (1.5MNPK and SNPK) increased the soil organic matter in alkoxy carbonyl carbon carbon and the ratio of cumulative carbonyl carbon mainly occurs in large aggregates and micro aggregates. The long-term application of chemical fertilizer (N NPK) and alkyl carbon in soils increased significantly, the proportion of aromatic carbon and carbonyl carbon decreased, increasing the ratio of alkyl alkoxy carbon / carbon, accelerate the mineralization of organic matter decomposition. Show that long-term application of organic manure into a large number of carbohydrates and organic acids, to enhance the stability of soil organic matter through the large aggregates and micro aggregates chemical protection of organic carbon, thereby improving soil organic carbon content. The distribution of soil animal community is closely related with the properties of different fertilizer. Applying organic materials (1.5MNPK and SNPK) to soil Animal survival, can continue to increase the total number of individuals of soil animal communities and the total number of groups, and balanced fertilizer (NPK) can only enhance the richness of the soil animal community. The total individual number of soil animal community and diversity index (H ') dimer with mass fraction of organic carbon content and large aggregates are positive the correlation with silt + clay group and clusters, that aggregates provide nutrition rich source of energy for the soil animal community, and the diversity of soil animal communities also promoted the soil aggregation degree of.24 years continuous long-term application of organic fertilizer (1.5MNPK), total organic carbon and grey desert soil. With fertilization time increased, the sand with organic carbon fractions in response to fertilization is more sensitive, the largest increase, effects on soil total organic carbon accumulation is higher than that of other components. There is light Organic matter (free of coarse particulate organic carbon free and fine particulate organic carbon) fraction in response to changes in soil nutrients more active, physical protection of organic carbon in aggregates in the soil nutrient supply and soil total organic carbon sequestration plays a very important role.

【学位授予单位】：新疆农业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S151.9

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