侵蚀红壤中结合态腐殖质及其与水稳性团聚体的关系

以亚热带地区3种侵蚀程度(依据其植被、坡度以及土层厚度不同分为轻度、中度和严重侵蚀)的红壤为供试材料,利用湿筛法获得粒径4、2~4、1~2、0.5~1、0.25~0.5 mm的水稳性团聚体,分析侵蚀红壤和团聚体中3种结合态(紧结态、松结态和稳结态)腐殖质含碳量的分布特征,及其对0.25 mm团聚体稳定性的影响。结果表明:随着红壤侵蚀程度的增强,3种结合态腐殖质的含碳量均逐渐减小。在轻度侵蚀的红壤中,随着团聚体粒径的增大,其紧结态和松结态腐殖质的含碳量逐渐升高,稳结态腐殖质的含碳量逐渐降低;但是在中度和严重侵蚀红壤中,不同粒径团聚体的3种结合态腐殖质的含碳量基本相同。侵蚀红壤的紧结态、松结态腐殖质的含碳量与其0.25 mm水稳性团聚体的含量均呈极显著正相关(r分别为0.88,0.74),说明土壤中腐殖质与矿物质的结合方式和松紧程度不一样,其对侵蚀红壤的结构具有不同的影响。     

几种侵蚀红壤中有机质和团聚体的关系

以3种侵蚀红壤（轻度、中度、严重）为供试材料,利用干湿筛法获得其不同粒径的水稳性团聚体（〉4 mm,2～4 mm,1～2 mm,0.5～1 mm,0.25～0.5 mm）,分析团聚体中有机质的分布。结果显示,随着侵蚀程度的增强,〉0.25mm水稳性团聚体的含量逐渐下降,而团聚体的分散度却依次升高;无论何种侵蚀程度,湿筛后团聚体的组成均以小粒径团聚体（〈0.25 mm）占优势。轻度和中度侵蚀的红壤,其有机质含量随着团聚体粒径的增大而增大,严重侵蚀的则相反;侵蚀红壤有机质含量和〉0.25 mm水稳定性团聚体呈显著正相关,3种侵蚀红壤团聚体对土壤有机质的贡献为轻度侵蚀〉中度侵蚀〉严重侵蚀。     

红壤表土团聚体稳定性对坡面侵蚀的影响

通过野外人工模拟降雨试验,研究了第四纪红粘土、泥质页岩和花岗岩三种母质发育的红壤团聚体稳定性对土壤坡面侵蚀和侵蚀泥沙特性的影响.结果表明：坡面土壤侵蚀量和径流强度与土壤团聚体稳定性存在显著负相关关系,且不同团聚体稳定性指标与二者相关程度存在差异,其中湿筛团聚体平均重量直径（MWD）和》0.25 mm水稳性团聚体含量（WSA0.25）与侵蚀量和径流强度相关程度最高,快速湿润中1～0.5 mm团聚体和湿润振荡中2～1 mm团聚体标准化平均重量直径（NMWD）与二者的相关性也达到了显著;泥沙粒径与湿筛MWD和WSA0.25之间相关关系（偏相关分析）呈显著正相关（r=0.8283^＊,r=0.8209^＊）;快速湿润中1～0.5 mm团聚体和湿润振荡中2～1 mm团聚体的NMWD与泥沙粒径也存在较好正相关关系（r=0.7458,r=0.6859）.泥沙粒径和水流功率在本研究中未表现出较好相关性（r=-0.1852）.     

施用生物质炭对黑土腐殖质组成及水稳性团聚体分布的影响

为探究生物炭对土壤腐殖质组成和团聚体特征的影响，以东北黑土区植烟土壤为研究对象，设置了3个处理，2019-2020年连续施用低量生物炭5t/hm2（C1）；高量生物炭25t/hm2（C2）和不施生物炭（CK），分析了不同用量生物炭对土壤腐殖质组分及水稳性团聚体分布的影响，并利用傅里叶红外光谱(FTIR)和13C核磁共振光谱(13C-NMR)对土壤胡敏酸化学结构进行表征。结果表明：C1和C2处理分别使富里酸减少了16.90%和40.85%，胡敏酸含量显著增加了14.86%和33.78%，胡敏酸在腐殖酸中所占比例（PQ值）也显著增加；FTIR和13C-NMR分析表明，C2处理的土壤胡敏酸的2920/1620值降低了11.82%，脂族C/芳香C比值降低了13.04%，表明高量生物炭使胡敏酸芳构化程度增强，脂肪结构比例降低；生物炭的添加促使土壤大团聚体（>0.25mm）比例增加，C2处理提升大团聚体的作用更显著。结合相关性分析发现，胡敏酸含量与2~0.25mm大团聚体含量显著正相关，胡敏酸分子的脂肪族官能团特征与>2mm粒级团聚体显著正相关。此外，C1和C2处理显著提高了烟叶产量。从而表明，生物炭能提升土壤腐殖质中胡敏酸含量和结构，有利于土壤大团聚体形成，提高土壤固碳潜力，对作物有一定的增产效果。     

侵蚀程度对红壤团聚体分布及养分含量的影响

[目的]探讨不同侵蚀程度下红壤团聚体和养分的变化规律,为侵蚀红壤的肥力提升和合理开发利用提供理论依据。[方法]将红壤表层按照不同深度剥离来模拟不同土壤侵蚀程度,比较分析不同侵蚀程度下团聚体稳定性、有机质和各养分的变化规律及其相互关系。[结果]各侵蚀程度红壤团聚体干筛粒级分布规律大体相似,以≥2mm粒级团聚体为优势粒级,与无明显侵蚀土壤相比,强烈侵蚀土壤≥2mm水稳性团聚体含量降低近1/3;随着土壤侵蚀程度增加,土壤碳、氮、磷等养分含量均表现出逐渐减少的规律,其中强烈侵蚀土壤有机质、全氮和全磷含量减少了30%左右,碱解氮含量减少了近50%,速效磷含量减少了80%以上。相关分析表明,土壤有机质、全氮、全磷、碱解氮含量均与≥2 mm团聚体含量、WSA,MWD和GMD值具有较好的正相关性(p0.05),与D和PAD值呈负相关。[结论]不同侵蚀程度对红壤团聚体分布及养分含量有一定影响,可通过增加有机肥来改善侵蚀红壤结构,提高土壤肥力。     

侵蚀程度对不同粒径团聚体中养分含量和红壤有机质稳定性的影响

以三种侵蚀程度的红壤(轻度、中度、严重)为供试材料,研究其>0.25 mm水稳性团聚体中的养分(全氮、全磷、全钾、有机质)和不同形态有机碳(易氧化态和难氧化态)的含量状况和分布特点。结果表明:随着红壤由轻度、中度到严重侵蚀的变化,>0.25 mm水稳性团聚体中有机质、全氮和全磷含量逐渐降低;>0.25 mm水稳性团聚体中的养分对土壤养分的贡献率为[>4 mm]>[0.5～1 mm]>[1～2 mm]>[2～4 mm]>[0.25～0.5 mm];侵蚀红壤的全氮、全磷和有机质均与>0.25 mm水稳性团聚体含量显著正相关。土壤有机碳、易氧化碳和难氧化碳的含量随着红壤侵蚀程度的增强逐渐降低,并且均与>0.25 mm水稳性团聚体、有机质、全氮、全磷呈极显著正相关。有机质氧化稳定性系数与不同粒径水稳性团聚体、土壤有机质、全氮和全磷均呈负相关。     

植被恢复对亚热带侵蚀红壤团聚体养分分布的影响

为深入了解不同植被恢复年限下土壤团聚体养分分布特征,以典型红壤侵蚀区福建省长汀县河田地区恢复年限分别为0,5,10,15,30,80a的坡地土壤为研究对象,分别对0—20cm和20—40cm土层不同粒径团聚体养分含量进行测定,并分析了它们与不同团聚体的相关关系。结果表明:(1)植被恢复过程中,土壤团聚体有机碳、全氮、全磷、全钾、速效磷和速效钾含量的变化范围分别为2.06~27.71g/kg,0.54~2.12g/kg,0.034~0.171g/kg,2.20~6.89g/kg,0.31~3.30mg/kg和7.35~85.71g/kg;(2)有机碳、全氮、全磷和速效磷含量随着团聚体粒径的减小总体上表现出显著升高趋势(P0.05),全钾和速效钾含量无明显差异(P0.05);(3)随植被恢复年限增加,各粒径团聚体中有机碳、全氮、全磷、速效磷含量总体上呈显著升高趋势(P0.05),全钾含量先升高后降低,而速效钾含量表现出波动增加趋势;(4)恢复初期(0a和5a)不同土层间团聚体养分含量无明显变化(P0.05),其它恢复年限0—20cm土层团聚体有机碳、全氮、全磷、速效磷和速效钾含量显著高于20—40cm土层(P0.05);(5)团聚体对土壤养分的贡献率表现为(5mm)(2~5mm)(0.5~1mm)(1~2mm)(0.25~0.5mm)(0.25mm),2mm粒径养分贡献率达34.18%~49.93%,土壤养分含量与0.25mm粒径相关性较强(P0.01)。植被恢复在降低土壤侵蚀的同时,土壤团聚体养分含量明显增加,土壤结构得以改善,养分固持能力得到加强。     

不同腐殖酸组分对湖泊沉积物中重金属释放的影响

腐殖酸作为湖泊沉积物中有机质的主要成分．对重金属具有强烈的富集能力，从而影响湖泊沉积物中重金属向水中的释放。本文深入探讨了腐殖酸的不同组分对沉积物中Cu、Zn、Pb、Cd向水中释放的影响。结果表明：腐殖酸的添加使沉积物中重金属的释放置明显受到影响。Cu、Zn、Pb、CA4种重金属随着胡敏酸和富里酸的添加．释放量逐渐增加，并且两种腐殖酸的用量越大．重金属的释放量越大。向沉积物中加入同等量的胡敏酸、富里酸，两种腐殖酸对重金属释放的促进作用胡敏酸〉富里酸。向沉积物中加入不同用量的富里酸FA，沉积物中Cu、Zn、Pb、Cd的释放率分别为73％～80％，18．5％～22％，7．5％～10％．97％～99％；而在相同条件下，向沉积物中加入不同用量的胡敏酸HA，对以上4种重金属的释放率分别为66．5％～72％，15．5％～19．5％．6％～8．5％，96％～98．5％。在腐殖酸用量相同的情况下，溶液的pH对沉积物中重金属的释放也会产生影响。即随着pH值上升．释放量逐渐减少。当pH=8时，释放量基本上已不再发生变化，说明此时沉积物中的重金属基本上与腐殖酸的羧基反应完毕。     

不同C/N对堆肥腐殖酸的影响

以鸡粪、稻草为原料,采用条垛式高温堆肥,研究C/N对堆肥腐殖酸的影响.结果表明,C/N对富里酸生成无显著影响;C/N在20～35间有利于总腐殖酸和水溶性腐殖酸的形成;C/N在20～30间有利于游离腐殖酸和胡敏酸的生成;C/N为30,堆肥腐熟后总腐殖酸生成量最多.     

不同修复措施下红壤水稳性团聚体中有机质分布特征

试验设置作物对照(CK)、作物+PAM(聚丙烯乙酰)(C1)、作物+稻草覆盖(C2)、作物+带状牧草(C3)、作物+PAM+带状牧草(C4)和作物+稻草覆盖+带状牧草(C5)6个处理,分别于种植花生前(A)、花生收获后(B)和小麦收获后(C)采集表层土样,研究不同修复措施下鄂东南侵蚀红壤团聚体的稳定性及水稳性团聚体中有机质的分布特征。结果表明,C时期各处理>0.25mm水稳性团聚体含量的平均值比A时期提高了24.78%,以C2处理的水稳性团聚体含量最高。不同时期土壤和各级水稳性团聚体中有机质含量表现为B>C>A。随着团聚体粒径(>4mm,4～2mm,2～1mm,1～0.5mm,0.5～0.25mm)减小,水稳性团聚体中有机质含量逐渐降低。土壤有机质含量与各粒径水稳性团聚体有机质含量呈线性正相关,小粒径(2～0.25mm)水稳性团聚体的有机质含量与土壤有机质含量呈极显著正相关(相关系数为0.779 2～0.828 6)。综合考虑土壤有机质含量和团聚体稳定性2个因素,稻草覆盖措施对侵蚀红壤的修复效果较好。     

Surface versus incorporated residue effects on water-stable aggregates

Reduced tillage methods for field crop production result in less disruption of soil structure and often increased amounts of crop residue maintained on the soil surface. The combination of these two factors produces increased surface soil aggregation. This study was conducted in the field and within pots to determine whether surface residue by itself improves soil aggregation within a short period of time. The soil was a silt loam loess deposit in the Pacific Northwest, USA, where summers are hot and dry, and most precipitation (420 mm) is received during the mild winters. Two pot studies were conducted over winter, one under a shelter with controlled irrigations (183 mm), and the other outdoors receiving natural precipitation (77 mm). In both pot studies 640 g m⁻² wheat (Triticum aestivum L.) residue was either placed on the surface of the soil or thoroughly mixed into the soil. The field study was conducted on plots where, for the past 7 years, wheat crop residues were either incorporated through chisel/disk tillage or removed before tillage and replaced on the surface after tillage. The field study included plots where wheat was grown with no tillage. In the pots, there was no significant effect due to residue treatment on aggregate mean weight diameter, measured monthly for 4 winter months. This was true despite dissolved organic carbon being leached from the surface residue. In the 7-year-old field plots, replacing residues on the surface resulted in slightly greater mean weight diameter of aggregates at 5–10 cm depth compared to the mixed residue treatment. The no-till plots had significantly greater mean weight diameter at 0–5 cm depth than either tilled treatment. Our conclusion is that surface residue by itself failed to increase aggregation of tilled surface soil within the first rainy season after tillage.     

不同种植模式下菜地土壤腐殖质组分特性的动态变化

通过在南京普朗克有机农场开展的9年长期定位监测,研究了有机(露地和大棚)和常规种植模式下蔬菜地耕层土壤有机碳和土壤腐殖质组分特性的动态变化。结果表明,有机露地、有机大棚和常规露地种植土壤有机碳含量分别从11.41、9.29、9.00 g k g-1提高至15.35、20.90、10.00 g kg-1;胡敏酸碳(CHA)分别从1.79、1.23、1.14 g kg-1提高至2.11、3.11、1.31 g kg-1;富里酸碳(CFA)分别从2.19、1.88、1.73 g kg-1提高至2.44、2.68、1.91 g kg-1。两种有机种植模式的土壤有机碳及腐殖质组分含量增加达到显著水平,而常规种植模式下的变化不显著。两种有机种植模式下表征土壤腐殖质品质的胡/富比(CHA/CFA)、胡敏酸占总腐殖物质的比例(PQ值)均高于常规种植模式,土壤富里酸的E4/E6值、色调系数(ΔlogK)值随着种植时间增加的幅度较常规种植模式更大,土壤胡敏酸芳化度呈现先降低后增高的趋势,但在常规种植下变化不明显。说明土壤在长期有机种植模式下不仅更有利于土壤有机碳的积累,而且能促进土壤腐殖化进程。     

The effect of tea plantation age on soil water-stable aggregates and aggregate-associated carbohydrate in southwestern China

Soil carbohydrates constitute an important component of soil organic matter (SOM), and substantially contribute to the stabilization of soil aggregates. Here, we aimed to investigate the distribution of water-stable aggregates and carbohydrates within water-stable aggregates of soil in tea plantations located in Zhongfeng Township of Mingshan County, Sichuan, which is in southwest China. Samples were collected from tea plantations of different ages (18, 25, 33, and 55 years old) and an area of abandoned land was used as a control(CK). We also examined correlations between soil carbohydrates fractions and aggregate stability. The results showed that the mean weight diameter (MWD) of soil aggregates in the tea plantations was significantly higher than that the control. Furthermore, the soil aggregate stability was significantly enhanced in tea plantations, with the 25-year-old plantation showing the most pronounced effect. Soils in the plantations were also characterized by higher concentrated acid-extracted carbohydrate content, and carbohydrate content in both surface and sub-surface layers were higher in the 25-year-old plantation. We also detected a significant positive correlation between the carbohydrate content of soil and MWD after tea plantation (P < 0.01). Notably, the association between dilute-acid extracted carbohydrate and the aggregate stability showed the highest correlation, indicating this carbohydrate fraction could be used as an index to reflect changes in soil quality during tea plantation development. We should develop a potential fertilisation programme to maintain SOM- Carbohydrates within aggregates and the appropriate pH for preventing soil structure degradation after 25 years of tea planting.     

高黎贡山土壤腐殖质特性与团聚体数量特征研究

采用野外调查与室内分析结合的方法,研究高黎贡山土壤腐殖质特性与团聚体数量特征,对进一步了解高黎贡山生态系统中土壤特征,降低土壤侵蚀,减少水土流失提供科学依据。结果表明:土壤腐殖质的组成具有明显地带性特征,有机质、腐殖酸含量、胡/富(HA/FA)随海拔高度的降低呈先上升后下降的趋势,A1层胡敏酸(HA)、富里酸(FA)含量分布规律为暗棕壤棕壤棕色针叶林土亚高山草甸土黄棕壤黄壤黄红壤。A2层腐殖酸、FA变化趋势为暗棕壤棕壤棕色针叶林土黄棕壤黄壤亚高山草甸土黄红壤。A1层HA、FA分子复杂程度、化学稳定性比A2层强。1～0.5mm和0.25mm粒径的团聚体含量占绝大多数,约占60%～70%。随着海拔高度的降低,粗粒减少,细粒增多。土壤团聚体服从对数正态分布,其几何平均直径与几何标准差、土壤可蚀性K值之间存在负相关关系,土壤可蚀性K值与几何标准差存在正相关关系,同时土壤也具有一定的分形特性。其中亚高山草甸土几何平均直径(Dg)、平均重量直径(MWD)值最大,几何标准差(δg)、可蚀性K值、分形维数(CFD)值最小,土壤结构稳定性和抗蚀能力相对较强。胡敏酸含量是影响土壤可蚀性的重要因素。     

氮肥及黄腐酸对盐渍土有机碳和团聚体特征的调控作用

为了探明不同氮肥水平下黄腐酸对盐碱障碍土壤的改良及培肥效应,本研究以滨海滩涂新垦轻中度盐碱障碍土壤为研究对象开展田间试验,采用水稻-小麦轮作种植模式,通过测定土壤电导率、pH、有机碳和土壤团聚体含量及其稳定性,研究黄腐酸与不同氮肥水平对土壤盐分消减调控和土壤地力提升效应。结果表明:黄腐酸能有效降低耕层土壤盐分,在氮水平300 kg/hm²条件下黄腐酸处理对耕层0～20 cm土壤电导率与p H降低效果最好;黄腐酸可以有效改善土壤结构及稳定性,小麦季与水稻季,在氮水平300kg/hm²条件下黄腐酸处理土壤>2mm水稳性大团聚体含量相较于不施肥对照分别增加18.6%和13.8%,土壤团聚体平均重量直径与当地常规施肥相比增加38%;围垦初期,氮水平处理相较于黄腐酸处理对耕层土壤有机碳含量的影响更大,氮水平300kg/hm²处理相较于低氮(225kg/hm²)与高氮(325kg/hm²)处理,两季土壤总有机碳积累量分别增加31.0%和120.0%。综合考虑土壤改良效应,黄腐酸处理土...     

不同来源腐殖酸的组成和性质的研究

本研究从三种有机物料草炭、褐煤、风化煤中提取腐殖酸,对其组成和性质进行了测定,同时对胡敏酸进行酒精沉淀分级。研究结果表明:褐煤胡敏酸氧化度和芳香度最高,其次为风化煤胡敏酸,最后是草炭胡敏酸;风化煤富里酸的氧化度和芳香度最高,其次为褐煤富里酸和草炭富里酸。胡敏酸各级分的回收率均随着级分数的升高而增加。回收率以风化煤胡敏酸最高,依次为褐煤胡敏酸、草炭胡敏酸。     

PAM对黄土高原主要土壤类型水稳性团聚体的改良效果及机理研究

通过室内土柱培养,研究PAM对黑垆土、黄绵土、风沙土水稳性团聚体的改良效果,并探讨其作用机理和合理的施用浓度.结果表明,在浓度为0.05%～0.4%,PAM均可促进3种土壤＞0.25 mm水稳性团聚体的形成,并有效降低3种土壤团聚体分形维数,改善土壤结构;方差分析表明,PAM改良3种土壤结构的机理是一致的,将＜1mm的水稳性团聚体聚合为更大粒径的水稳性团聚体,使＞1mm的水稳性团聚体含量增加.PAM改良黑垆土、黄绵土和风沙土土壤水稳性团聚体达到显著水平时的浓度也不相同,其适宜浓度分别为0.2%～0.4%,0.05%,0.05%.3种土壤的黏粒含量和有机质含量的差异,可能是影响PAM对不同土壤的水稳性团聚体的改良效果差异的主要原因.     

黑土轻组分C与团聚体水稳性的关系

To evaluate the role of kaolinite and variable charge soils on the hydrolytic reaction of Al, the hydrolysis of Al ions in suspensions of a kaolinite and an Oxisol influenced by organic anions was investigated using changes of pH, Al adsorption, and desorption of pre-adsorbed Al. Kaolinite and the Oxisol promoted the hydrolytic reaction of Al above a certain initial Al concentration （0.1 mmol L^-1 for kaolinite and 0.3 mmol L^-1 for the Oxisol）. The Al hydrolysis accelerated by kaolinite and the Oxisol increased with an increase in initial concentration of Al and was observed in the range of pH from 3.7 to 4.7 for kaolinite and 3.9 to 4.9 for the Oxisol. The acceleration of Al hydrolysis also increased with the increase of solution pH, reached a maximum value at pH 4.5, and then decreased sharply. Al hydrolysis was promoted mainly through selective adsorption for hydroxy-Al. Soil free iron oxides compensated a portion of the soil negative charge or masked some soil surface negative sites leading to a decrease in Al adsorption, which retarded acceleration to some extent. For the Oxisol organic anions increased the proportion of adsorbed Al^3＋ in total adsorbed Al with the increase in soil negative surface charge and eliminated or reduced the acceleration of Al hydrolysis. Different organic anions inhibited the hydrolysis of Al in the order： citrate 〉 oxalate 〉 acetate （under initial pH of 4.5）. The formation of Al-organic complexes in solution also inhibited the hydrolysis of Al.