农业恢复措施对黑土母质发育的新成土土壤结构性质的影响

发布时间：2018-05-05 16:18

本文选题：农业恢复措施 + 土壤孔隙结构　；参考：《中国农业科学院》2015年硕士论文

【摘要】：土壤结构控制土壤水分、养分的储存运输和气体扩散,调控土壤微生物活动,因此决定了土壤生态服务功能。农业恢复措施通过调控土壤结构影响土壤肥力,但是相关知识主要来自于对成熟土壤的研究,关于在土壤成土初级阶段农业恢复措施如何影响新成土土壤结构的报道很少。本研究假设耕作措施和有机物还田能加速初始成土过程及土壤结构形成,从而导致不同处理土壤孔隙结构性质产生差异。利用中国科学院海伦农业生态实验站设立的8年黑土母质成土过程模拟试验,应用μCT技术,辅以BET氮气吸附法和压力膜仪法定量孔隙结构性质,本研究将从:1)土壤有机质和团聚体稳定性;2)孔隙分布变化;3)孔隙不同定量方法的差异;三方面揭示不同农业恢复措施对新成土壤结构性质的改变。田间处理包括不耕作的自然恢复(NatF)、种植牧草(Alfa)和相同耕作体系结合不同化肥(F)与有机质(C)改良的土壤处理F0C0、F1C0、F1C1、F1C2;并设母质(PM)和成熟黑土(MO)2个对照。主要结果如下:(1)经过8年田间试验,各试验处理土壤理化性质、有机质含量、团聚体稳定性都得到改善,仅F1C1和F1C2处理的阳离子交换量减小;各试验处理土壤与成熟黑土仍有较大差距或差异。与不耕作处理相比,耕作降低土壤容重、团聚体稳定性;秸秆覆盖还田、翻耕还田,增加土壤有机质含量、土壤总氮含量,降低土壤容重,提高团聚体稳定性。黑土母质成土初级阶段的团聚体稳定机制与成熟黑土的不同,新成土在成土初期主要以年轻有机质为胶结物质,而成熟黑土以腐殖化程度高的有机质为胶结物质。(2)不同农业恢复措施对土壤团聚体吸附孔隙有影响,主要表现在各试验处理土壤比表面积、总孔容、2~50 nm、2 nm孔隙减少;有机质的增加,减小土壤比表面积和2 nm孔隙度。对土壤团聚体(3-5 mm)内部微形态的影响,主要体现在各试验处理土壤团聚体内部变得疏松多孔,三维孔隙结构连通性、复杂度提高。各试验处理土壤在二维和三维结构下已经比较接近黑土。耕作使小孔隙增加,在三维结构上表现更复杂,有机质使小孔隙减少,三维结构简化。对CT图像分析获得的土壤团聚体(3-5 mm)孔隙结构性质的影响,主要表现在各试验处理土壤总孔隙度、30μm孔隙度、孔隙数量增加,耕作施肥措施增加100μm的孔隙度和孔隙连通性,有机质降低孔隙的连续性,简化孔隙结构。(3)不同农业恢复措施对原状土(50 mm直径环刀,下同)孔隙结构的影响,表现在对于以水分特征曲线获得的孔隙,不耕作处理间比较,有机质增加原状土大于150μm和0.2~1μm的孔隙,减小30~150μm和小于0.2μm的孔隙;不耕作处理与耕作无有机质还田处理比较,耕作减少30~150μm孔隙,增加0.2-30μm孔隙。耕作处理间比较,有机质还田使原状土30~150μm孔隙增多,0.2~30μm孔隙减少。对土壤原状土内部微形态的影响,主要体现在与不耕作土壤比,耕作原状土内部变得疏松多孔,土块变小,次级团聚体增多,使大孔隙减少,次级孔隙增多,分布变均匀;由于环刀原状土孔隙非常多,三维可视化差异不显著。对CT图像分析获得的原状土孔隙结构性质的影响,主要表现在相同耕作体系下施化肥使土壤板结,形成大裂缝(5000μm),减少了次级大孔隙(500~5000μm);有机质还田增加总孔隙度、500~5000μm孔隙,减少5000μm孔隙。耕作结合有机质还田降低土壤孔隙连续性,增加孔隙连通性,使孔隙弯曲度减小,孔隙结构简单化。(4)结合不同分辨率CT扫描和图像分析技术对不同尺度土壤孔隙的评价,可以作为一种方法来评价土壤大孔隙系统。环刀原状土孔隙比团聚体孔隙通道更长,体积更大;而团聚体孔隙通道比环刀原状土孔隙通道要弯曲,形态复杂。耕作条件下有机质增加均降低土壤孔隙连续性,增加原状土孔隙连通性;耕作施肥措施增加团聚体孔隙连通性。
[Abstract]:Soil structure controls soil moisture, nutrient storage and transport and gas diffusion, and regulates soil microbial activity. Therefore, soil ecological services are determined. Agricultural recovery measures affect soil fertility by regulating soil structure, but the related knowledge mainly comes from the study of mature soil, and agricultural restorer at the primary stage of soil formation. This study assumes that cultivation measures and organic matter return to soil can accelerate the initial soil forming process and the formation of soil structure, resulting in different soil pore structure properties. The 8 year black soil parent material process established by the Helen agricultural ecological experiment station of the Chinese Academy of Sciences was used. Simulation test, using CT technology, supplemented by BET nitrogen adsorption method and pressure membrane meter method to quantify pore structure properties, this study will be from: 1) soil organic matter and aggregate stability; 2) pore distribution change; 3) the difference of different pore quantitative methods; three aspects of different agricultural recovery measures to new soil structure properties change. Field treatment Including natural restoration of non tillage (NatF), planting herbage (Alfa) and the same tillage system combined with different fertilizers (F) and organic matter (C) soil treated with F0C0, F1C0, F1C1, F1C2, and 2 controls of parent material (PM) and mature black soil (MO). The main results were as follows: (1) after 8 years of field experiments, the soil physical and chemical properties, organic matter content, and mass content were treated in each experiment. The stability of polymer was improved, and the amount of cation exchange was reduced only by F1C1 and F1C2, and there was still a big gap or difference between the soil and the mature black soil. Compared with the non tillage treatment, the soil bulk density and aggregate stability were reduced by tillage, the straw mulching returned to the field, the soil organic matter content was increased, the total soil nitrogen content was reduced. Soil bulk density, increase the stability of aggregate. The stabilization mechanism of aggregate in the primary stage of the black soil is different from that of the mature black soil. The newly formed soil is mainly cemented with young organic matter in the early stage of soil formation, while the mature black soil is cemented with high humic degree of organic matter. (2) different agricultural recovery measures on soil aggregate adsorption hole The effect of the gap is mainly manifested in the soil surface area, total pore volume, 2~50 nm, 2 nm porosity, the increase of organic matter, the decrease of soil specific surface area and 2 nm porosity. The influence on the internal micromorphology of soil aggregates (3-5 mm) is mainly reflected in the porous and porous structure of the soil aggregates in each test place, and the three-dimensional pore structure is connected. The soil is closer to the black soil in two and three dimensional structures. The cultivation makes the small pores increase, the three-dimensional structure is more complex, the organic matter reduces the small pores, and the three-dimensional structure is simplified. The effects of the pore structure properties of the soil aggregates (3-5 mm) obtained by CT image analysis are mainly expressed in each of the pore structures. The total porosity of soil, the porosity of 30 mu m, the increase of pore number, the increase of porosity and porosity of 100 mu by tillage fertilization, the decrease of pore continuity and the simplification of pore structure. (3) the effects of different agricultural recovery measures on the pore structure of the original soil (50 mm diameter ring knife, the same below) are manifested in the water characteristics. The pores obtained by the line were compared with that of the non tillage treatment. The organic matter increased the pores of the original soil greater than 150 m and 0.2~1 m, and reduced the pores of 30~150 mu m and less than 0.2 mu m. Compared with the non tillage treatment and tillage without organic matter returning, the tillage reduced the pore of 30~150 mu m and increased the pore gap of 0.2-30 micron m. The comparison between the tillage treatment and the return of organic matter to the soil made the original soil 30~1 The pores of 50 mu m and the pore of 0.2~30 mu m decrease. The influence on the internal micromorphology of soil original soil is mainly reflected in the comparison with the non tillage soil, the loose soil in the original soil, the smaller soil mass, the increase of the secondary aggregates, the decrease of the macropores, the increase of the secondary pores and the distribution of the secondary pores. The effects on the properties of the pore structure of the original soil obtained by the CT image analysis are mainly manifested in the application of chemical fertilizer to soil consolidation under the same tillage system, the formation of large fissure (5000 mu m), the reduction of the secondary macropores (500~5000 mu m), the total porosity of the organic matter, the porosity of 500~5000 micron m, the porosity of 5000 mu m, and the combination of organic matter and organic matter. Reducing soil pore continuity, increasing pore connectivity, reducing pore curvature and simplifying pore structure. (4) evaluation of soil pores in different scales with different resolution CT scanning and image analysis techniques can be used as a method to evaluate the soil macropore system. The pore passage of the aggregate is more complicated than the pore channel of the loop knife original soil. The increase of organic matter in the condition of cultivation reduces the continuity of the soil pore and increases the porosity connectivity of the original soil, and the cultivation and fertilization measures increase the pore connectivity of the aggregate.

【学位授予单位】：中国农业科学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S152

【参考文献】