采煤塌陷区复垦土壤团聚体碳氮分布对施肥的响应

为了揭示长期不同培肥措施下采煤塌陷区复垦土壤团聚体有机碳氮含量的变化规律,通过干筛法研究了不施肥(CK)、单施有机肥(M)、单施化肥(CF)、有机肥与化肥配施(MCF)、生物有机肥与化肥配施(MCFB)5种培肥措施下复垦4年和8年土壤各粒级团聚体分布组成特征以及各团聚体有机碳氮含量的变化规律。结果表明,复垦土壤团聚体含量随粒级减小呈先减小后增大的变化趋势,其中以3~2mm粒级团聚体含量最低,占团聚体总量2%~3%,以2~1mm粒级团聚体含量最高,占团聚体总量25%~31%。不同培肥措施下复垦4年和8年土壤团聚体分布特征无明显差异,但较未复垦生土明显降低了7mm和7~5mm团聚体含量。复垦8年土壤的平均重量直径(MWD)、几何平均直径(GMD)高于复垦4年土壤,分形维数(D)值低于复垦4年土壤。各培肥处理间以单施有机肥MWD、GMD值最高,D值最低。各培肥处理土壤团聚体有机碳氮含量随粒径减小递增,以0.5~0.25mm粒径团聚体最高,而有机碳储量以2~1mm粒级团聚体最高,分别占24.2%~33.8%和17.0%~33.1%。各处理间有机碳氮含量以单施有机肥处理最高,但不同处理间有机碳氮储量无显著差异。总体表明,采煤塌陷区复垦4年和8年土壤团聚体分布特征及碳氮储量无明显变化,单施有机肥可提高复垦土壤团聚体有机碳氮含量及团聚体稳定性。     

秸秆还田与生物炭施用对黄褐土团聚体稳定性及有机碳积累的影响

探明生物炭、秸秆和化肥配施对黄褐土条件下土壤团聚体的影响,为降低黄淮海平原黄褐土生产障碍,建立合理培肥制度提供参考。本研究通过3年定位试验,设置了不同的施肥制度:对照为不施肥(CK)、施用化肥(NPK)、生物炭配施化肥(NPKB)、秸秆配施化肥(NPKS)、生物炭和秸秆配施化肥(NPKSB)5个处理。对不同处理条件下湿筛的土壤团聚体指标进行了分析。结果表明:施用有机物料后,能增加大粒级土壤团聚体含量,提升土壤团聚体稳定性,提高土壤有机质含量。稳定性的提升幅度次序为NPKSNPKSBNPKB。在试验期内,添加生物炭能逐年提升土壤有机碳含量,顺序为NPKSBNPKB。在所有施肥处理中,NPKSB对提升大粒级团聚体有机碳贡献率效果最好。在本研究设置处理中,NPKSB对提升土壤团聚体基本性能效果最好。     

长期不同施肥管理对稻田土壤有机碳库特征的影响

以19年的长期定位施肥土壤为材料,研究不同施肥管理:不施肥(CK),施无机肥(N、NP、NK、NPK),施有机肥(OM),有机-无机配施(F、F')下稻田耕层土壤有机碳库组分及含量变化.结果表明:不同施肥方式对土壤有机碳及其组分有显著影响,土壤总有机碳(TOC)变化趋势为有机无机配施(平均12.34g/kg)>单施有机肥(平均12.15 g/kg)>无肥(平均10.56 g/kg)>化肥(平均9.78 g/kg);有机肥和化肥配施土壤徽生物量碳(SMBC)、水溶性有机碳(WSOC)、轻组有机碳(LFOC)及SMl3(2/TOC、WSOC/TOC、LFOC/TOC均显著高于单施化肥土壤的.与不施肥相比,化肥、有机肥的施用均显著增加了土壤重组有机碳(HFOC)和HFOC/TOC,其中,化肥的施用更有利于土壤重组有机碳(LFOC)的积累.单施有机肥或有机无机配施显著增加了较大粒级(>0.25 mm)水稳性团聚体及其TOC含量,而单施化肥则显著增加了较小粒级(<0.25 mm)及其TOC含量.因此,长期施用有机肥,特别是有机肥与无机肥配施能提高土壤活性碳含量和土壤团聚体稳定性,从而保持和提高了土壤质量和持续生产力.     

长期施肥紫色水稻土团聚体稳定性及其固碳特征

【目的】探讨长期不同施肥对土壤团聚体分布及其稳定性的影响,以及团聚体中有机碳对碳投入的响应。【方法】采集经历30年不同施肥处理后的紫色水稻土,利用湿筛法分离2 mm、0.25~2mm、0.053~0.25mm和0.053 mm团聚体组分,并分析团聚体的稳定性以及年均碳投入量和有机碳固定速率的关系。【结果】与不施肥(CK)比较,施肥(N、NP、NPK、M、MN、MNP和MNPK)使2 mm团聚体所占比例提高了9.6%~36.1%,0.25~2 mm团聚体降低了6.7%~26.3%,0.053~0.25 mm和0.053 mm团聚体所占比例基本稳定;单施化肥处理(N、NP和NPK)没有显著提高土壤团聚体的稳定性,化肥与有机肥配施(MNP和MNPK)显著增加团聚体的稳定性。与CK相比施肥显著增加土壤总有机碳和2 mm团聚体有机碳含量,其他粒径团聚体碳含量略有提高,但未达显著水平;化肥配施有机肥对团聚体有机碳含量增加效果优于单施化肥。CK和N处理土壤有机碳损失速率为0.08t/(hm~2·a)和0.02 t/(hm~2·a),单施化肥(NP和NPK)、单施有机肥(M)、化肥配施有机肥(MN、MNP和MNPK)处理土壤有机碳的固定速率分别为0.14、0.10和0.17t/(hm2·a)。土壤有机碳的固定速率与碳投入呈显著的线性相关关系(R~2=0.531,P0.05);碳转化效率为3.3%;随碳投入的增加,各粒径团聚体碳含量均增加,且2 mm团聚体的碳增加速率远远高于其他团聚体。【结论】化肥配施有机肥增强团聚体稳定性效果优于单施化肥;本试验紫色水稻土的有机碳还没有达到饱和,仍具有一定固碳潜力,增加的有机碳主要固持在2 mm团聚体中。     

长期施肥条件下红壤有机碳化学结构与团聚体稳定性的关系

[目的]红壤普遍存在团聚体结构较差和有机碳含量较低的问题,土壤有机碳是影响土壤团聚体结构的重要指标,但以往研究主要关注有机碳含量与团聚体的相关关系,而对有机碳的化学结构如何调控团聚体结构则缺乏深入研究.[方法]依托始于1986年的红壤旱地长期施肥试验,选取不施肥(CK)、施用氮磷肥(NP)、施用氮磷钾肥(NPK)、施用...     

长期施肥对稻麦轮作紫色土有机碳组分及酶活性的影响

为了探明西南地区长期不同施肥处理对稻麦轮作紫色土有机碳组分和碳循环相关水解酶活性的影响,依托重庆北碚29年稻麦轮作紫色土长期定位试验,选取不施肥(CK)、单施氮磷钾肥(NPK)、有机无机配施(NPKM)、秸秆还田配施含氯化肥[(NPK)clS]和秸秆还田配施无机肥(NPKS)5个处理,测定土壤各组分有机碳含量及与土壤碳...     

长期施肥对红壤性水稻土团聚体活性有机碳的影响

在23年的长期田间定位试验区,研究了长期施肥对红壤性水稻土团聚体活性有机碳含量的影响。结果表明,在不施肥(CK)、无机肥(NPK)、有机肥(猪粪+紫云英绿肥)(OM)和无机肥与有机肥配施(NPKM)处理中,土壤团聚体活性有机碳含量均随深度的增加而降低。长期施用肥料,特别是有机肥与无机肥配施会提高土壤团聚体活性有机碳含量,从而保持和提高土壤有机碳库质量。不同粒级土壤团聚体中活性有机碳含量和团聚体活性有机碳占团聚体有机碳比率有差异,潜在可矿化碳含量和潜在可矿化碳占团聚体有机碳比率从高到低的顺序为:0.25~1mm、1~3mm、>3mm、0.05~0.25mm和<0.05mm;而可溶性有机碳含量和可溶性有机碳占团聚体有机碳比率从高到低的顺序为:0.05~0.25mm、0.25~1mm、1~3mm、>3mm和<0.05mm。不同施肥处理A层土壤团聚体潜在可矿化碳、可溶性有机碳含量都与土壤团聚体有机碳含量都呈极显著相关;P层除1~3mm团聚体外都呈显著相关。土壤微团聚体(<0.25mm)中有机碳的稳定性高于大团聚体(>0.25mm)。     

长期施肥与覆膜对半干旱区马铃薯农田土壤团聚体分布及其有机碳含量的影响

以国家土壤质量安定观测实验站黄绵土区的农田长期定位试验为研究平台,研究长期施肥与覆膜对半干旱区马铃薯农田土壤团聚体分布及其有机碳含量的影响。结果表明:耕层土壤团聚体占比随着粒径的减小呈先降低后增加的变化趋势,团聚体有机碳含量随粒径减小呈增加趋势。施肥显著影响马铃薯农田土壤团聚体分布及有机碳含量。长期化肥与有机肥配施(NPK+OM)和单施有机肥(OM)较单施化肥(NPK)显著增加>0.25 mm团聚体含量(R0.25)和平均质量直径(MWD),显著提高大团聚体(>1 mm)对有机碳的贡献率。长期施用有机肥(NPK+OM和OM)较单施化肥(NPK)显著增加0～20 cm土层土壤团聚体有机碳储量,增幅达63.5%～82.8%。长期覆膜导致>2 mm粒径的大团聚体数量和MWD显著下降,覆膜与单施化肥(NPK)对团聚体有机碳含量及其储量影响不明显。综上所述,在西北黄土丘陵半干旱区和黄绵土质地条件下,长期化肥与有机肥配施(NPK+OM)或单用有机肥(OM)可显著提高耕层土壤大团聚体含量(R0.25)及其稳定性,促进新碳向大团聚体富集,增加团聚体有机碳储量,有利于农田土壤固碳。地膜覆盖影响土壤团聚体的分布和稳定性,但对团聚体有机碳影响不明显。     

不同施肥制度下褐土微团聚体有机碳活性变化

通过8年田间定位试验,研究了不同施肥制度下褐土及其微团聚体有机碳活性变化规律。结果表明,褐土微团聚体有机碳活性随粒级的减小而增强,不同施肥制度下土壤微团聚体组成变化各异,不施肥主要是由于10~50μm粒级总有机碳和<10μm粒级易氧化有机碳储量减少而造成土壤有机碳活性降低,土壤肥力下降;单施常量NPK化肥处理呈同样的趋势;增量NPK化肥可保持有机碳活性和肥力不降低,但投入较高;有机肥(物)料配施常量NPK化肥主要是通过增加大粒级特别是10~50μm粒级总有机碳和易氧化有机碳储量而使有机碳活性和土壤肥力水平得到提高。采用有机肥(物)料配施常量NPK化肥是改善褐土肥力的有效措施。     

不同施肥处理对红壤性水稻土团聚体的分布及有机碳、氮含量的影响

土壤采自江西省红壤研究所历经22年的肥料定位试验地,各施肥处理为:不施肥(CK)、施N肥(N)、施P肥(P)、施K肥(K)、施N、P肥(NP)、施N、K肥(NK)、施N、P、K肥(NPK)、施双倍N、P、K肥(2NPK)、施N、P、K肥和有机肥(NPK OM).研究了不同施肥处理对水稻土团聚体分布的影响以及土壤有机C、N在各级团聚体上赋存的情况.研究结果表明:有机C、N主要分配在2～0.25 mm的大团聚体上,C/N比随着团聚体粒级的减少而降低;水稻土团聚体的形成与有机C(SOC)密切相关,表现出与“层次性“机制相符的现象;施P、K、NK肥和NPK OM显著提高大团聚体的含量和团聚体的稳定性;NPK OM也显著提高土壤有机C、N和各级团聚体上的有机C、N的含量.     

东北黑土活性有机碳、氮分布研究

通过对东北黑土区不同地点、不同层次的土壤样品的分析,探索活性有机碳(轻组有机C,N、颗粒有机C,N和易氧化有机C,N)在东北地区的分布情况。结果表明,随着纬度的增加,土壤活性有机C、N含量增加;随着深度的增加,土壤活性有机C、N含量减少。说明纬度低的地区,活性有机碳库转化较快,库容较小,而耕作措施相近的情况下,植物残体和根残体在有机C积累方面应予以重视。     

Density fractionation reworked: Reduce material and costs

Soil density fractionation is a common tool to separate organic matter of different function and turnover. But it has not been tested so far how much soil material is necessary to obtain reproducible results. A reduction of chemicals like polytungstate would further save valuable resources. Here, we show that soil weight reduction from 25 to 5 g was not significantly affecting fractionation results. Compared to the commonly used 10–25 g, this corresponds to a saving of resources of up to 80%.     

Labile and stable pools of organic matter in soil amended with sewage sludge biochar

One of the main advantages of using biochar for agricultural purposes is its ability to store carbon (C) in soil for a long-term. Studies of labile and stable fractions of soil organic matter (SOM) may be a good indicator of the dynamics of biochar in soils. This study evaluated the effects of applying sewage sludge biochar (SSB) in combination with mineral fertilizer on fractions of SOM. To conduct this evaluation, 15 Mg ha^?1 of SSB combined or not with mineral fertilizer (NPK) was applied to the soil in two cropping seasons. Apart from total organic C (TOC), the labile and stable fractions of SOM were also determined. The combined use of SSB and NPK resulted in higher TOC, a 22% to 40% increase compared to the control and to the NPK treatments, respectively. The SSB produced at a lower temperature increased the labile fractions of SOM, especially the microbial biomass C, showing its capacity to supply nutrients in the short-term. The stable pools of SOM are increased after adding SSB produced at a higher temperature. It was concluded that pyrolysis temperature is a key-factor that determines the potential of SSB to accumulate C in labile and stable fractions of SOM.     

Molecular composition and structure of organic matter in density fractions of soils amended with corn straw for five years

Corn straw is an important source of carbon (C),and when applied to soil,it alters the accumulation and distribution of organic C.However,the mechanistic pathways by which newly added C is stored and stabilized in soil remain a subject of interest and debate among scholars.In this study,we investigated the chemistry of organic matter in different density fractions of Haplic Cambisol (sandy clay loam) in a field experiment with corn straw at8 900 kg ha^-1year^-1under no tillag...     

The quality of exogenous organic matter: short-term effects on soil physical properties and soil organic matter fractions

We examined the short-term effect of five organic amendments and compared them to plots fertilized with inorganic fertilizer and unfertilized plots on aggregate stability and hydraulic conductivity, and on the OC and ON distribution in physically separated SOM fractions. After less than 1 year, the addition of organic amendments significantly increased ( P  <   0.01) the aggregate stability and hydraulic conductivity. The stability index ranged between 0.97 and 1.76 and the hydraulic conductivity between 1.23 and 2.80 × 10⁻³ m/s for the plots receiving organic amendments, compared with 0.34–0.43, and 0.42–0.64 × 10⁻³ m/s, respectively, for the unamended plots. There were significant differences between the organic amendments (P <  0.01), although these results were not unequivocal for both soil physical parameters. The total OC and ON content were significantly increased ( P  <   0.05) by only two applications of organic fertilizers: between 1.10 and 1.51% OC for the amended plots versus 0.98–1.08% for the unamended and between 0.092 and 0.131% ON versus 0.092–0.098% respectively. The amount of OC and ON in the free particulate organic matter fraction was also significantly increased ( P  <   0.05), but there were no significant differences ( P  <   0.05) in the OC and ON content in the POM occluded in micro-aggregates and in the silt + clay-sized organic matter fraction. The results showed that even in less than 1 year pronounced effects on soil physical properties and on the distribution of OC and ON in the SOM fractions occurred.     

土壤团聚体的形成与分散及其在农业生产上的应用

土壤团聚体是保持土壤水分和土壤透性的基本单元.本综述的目的是通过围绕团聚体理论的讨论,明确影响团聚体形成的因素,为农田维护提出可靠的理论依据.首先总结了团聚体形成的主要理论,即Emerson的粘团理论、Edwards和Bremner的微团聚体理论和Oades 及Waters的团聚体分级构建理论,然后讨论了土壤有机质、可溶性阳离子和氧化铁、铝3个影响团聚体形成的主要因素,最后分析了团聚体破坏的机理和评价团聚体稳定性的主要方法,指出保持土壤颗粒的凝聚状态、增加各种形态的土壤有机质是增加土壤团聚性的主要措施.     

土壤残渣有机质与固定态铵之间的关系

采集了全国不同类型的土壤40个,分析了土壤全氮、有机质、固定态铵、剩余有机质（KOBr处理后的土壤有机质）、残渣有机质（KOBr-HF处理后的土壤有机质）含量.结果表明,以2∶1型粘粒矿物为主土壤的残渣有机质含量与固定态铵含量之间呈极显著正相关（r=0.831^＊＊）,晶格之间存在的有机质（即残渣有机质与剩余有机质之差值）含量则与固定态铵含量之间也呈极显著正相关（r=0.832^＊＊）,而以1∶1型粘粒矿物为主土壤的残渣有机质含量和晶格有机质含量与固定态铵含量不相关;土壤剩余有机质、残渣有机质的含量分别为2.59 g kg^-1、3.70 g kg^-1,分别占土壤有机质的10%和16%.土壤残渣C/N比（平均值为16.69）明显高于原土壤（平均值为5.37）.     

Changes in Organic Matter of an Oxisol with the Addition of Soybean and Corn Residues,Nitrogen and Phosphorus

Plants with different photosynthetic cycles (C3 and C4) and different plant parts (root or shoot) contribute in different ways to soil organic carbon (SOC). In addition, phosphate and nitrogen fertilization also act differently on the SOC stock. In this study, roots or shoots of corn (C3) and soybean (C4) plants were incorporated into samples of an Oxisol, with or without the addition of nitrogen (N) and phosphorus (P) and had the emission of carbon (C)- carbon dioxide (CO₂) measured during 45 days. Subsequently, soil organic matter fractionation, carbon and nitrogen microbial biomass and 13C isotopic discrimination were performed. The greatest increment in SOC was observed by adding corn plant material rather than soybean material. For both crops, the greatest contribution to SOC was achieved by adding roots as compared to shoots. Phosphorus addition produced greater microbial activity, followed by the addition of NP and then the addition of only N.     

耕作对土壤有机物和土壤团聚体稳定性的影响

Agricultural sustainability relates directly to maintaining or enhancing soil quality. Soil quality studies in Canada during the 1980‘s showed that loss of soil organic matter (SOM) and soil aggregate stability was standard features of non-sustainable land management in agroecosystems. In this study total soil organic carbon (SOC), particulate organic matter (POM), POM-C as a percentage of total SOC, and aggregate stability were determined for three cultivated fields and three adjacent grassland fields to assess the impact of conventional agricultural management on soil quality. POM was investigated using solid-state ^13C nuclear magnetic resonance (NMR) to determine any qualitative differences that may be attributed to cultivation. Results show a highly significant loss in total SOC, POM and aggregate stability in the cultivated fields as compared to the grassland fields and a significant loss of POM-C as a percentage of total SOC.Integrated results of the NMR spectra of the POM show a loss in carbohydrate-C and an increase in aromatic-C in the cultivated fields, which translates to a loss of biological lability in the organic matter. Conventional cultivation decreased the quantity and quality of SOM and caused a loss in aggregate stability resulting in an overall decline in soil quality.     

Determination of organic matter in sewage sludges

Abstract

Procedures for determining organic matter indirectly and directly in sludges are described. A good agreement between chromic acid oxidation and dry—combustion elemental analysis methods of determining organic‐C was observed. Sludge organic matter content was determined directly by loss‐on‐ignition by thermal analysis. An average C factor of 1.68 to estimate the organic matter from organic‐C, obtained by chromic acid oxidation method, was calculated for aerobically digested sludges.