Free-living nematode community structure and distribution within vineyard soil aggregates under conventional and organic management practices

Soil biota play a crucial role in soil ecosystem stability, promoting organic matter decomposition and nutrient cycling. Compared to conventional farming,organic farming is known to improve soil properties such as aggregation. Despite the importance of soil microbial communities in soil biogeochemical processes, our knowledge of their dynamics is rudimentary, especially under different agricultural management practices. Here we studied the effects of vineyard management practices(conventional an...     

土壤水稳性大团聚体测定方法综述

 湿筛法是测定土壤团聚体粒径分布和稳定性的经典方法。土样在湿润过程中,同时发生了崩解、差异膨胀和物理化学分散作用。已有的湿润方法按湿润速度可分为快速湿润和慢速湿润,按土样所处的气压条件可分为常压湿润和高真空湿润。常压快速湿润过程中,水分沿毛管快速渗入土体,土壤内部封闭的空气被压缩,产生微型爆炸,对团聚体破坏较大;慢速湿润和真空湿润能使团聚体稳定性显著增大。如果是为全面了解土壤团聚体稳定性及粒径分布的信息,可对土样采用常压快速湿润和常压慢速湿润（或真空湿润）2种预湿润。湿筛的作用在于区分不同粒级的土壤颗粒,应尽量减小对团聚体颗粒进一步的磨蚀作用,因此湿筛过程中振动速度不能太快。筛目可以根据实验目的选择。     

Impact of 47 Years of No Tillage and Stubble Retention on Soil Aggregation and Carbon Distribution in a Vertisol

Aggregation often provides physical protection and stabilisation of soil organic carbon (C). No tillage (NT) coupled with stubble retention (SR) and nitrogen (N) fertiliser application (90 N, 90 kg N ha⁻¹ application) can help improve soil aggregation. However, information is lacking on the effect of long‐term NT, SR and N fertiliser (NT, SR + N) application on soil aggregation and C distribution in different aggregates in vertisols. We analysed the soil samples collected from 0‐ to 30‐cm depth from a long‐term (47 years) experiment for soil aggregation and aggregate‐associated C and N. This long‐term field experiment originally consisted of 12 treatments, having plot size of 61·9 × 6·4 m, and these plots were arranged in a randomised block design with four replications, covering an area of 1·9 ha. Soil organic C concentrations as well as stocks were significantly higher under the treatment of NT, SR + N only in 0–10 cm compared with other treatments such as conventional tillage, stubble burning + 0 N (no N application) and conventional tillage, SR + 0 N. Mineral‐associated organic C (MOC) of <0·053 mm was 5–12 times higher (r  = 0·68, p  < 0·05, n  = 32) compared with particulate organic C (POC) (>0·053 mm) in the 0‐ to 30‐cm layer. We found that NT, SR + N treatment had a positive impact on soil aggregation, as measured by the mean weight diameter (MWD) through wet sieving procedure, but only in the top 0‐ to 10‐cm depth. MWD had significant positive correlation with water stable aggregates (r  = 0·67, p  < 0·05). Unlike MWD, water stable aggregates were not affected by tillage and stubble management. Large macroaggregates (>2 mm) had significantly higher organic C and N concentrations than small macroaggregates (0·25–2 mm) or microaggregates (0·053–0·25 mm). We also found that N application had a significant effect on MWD and soil organic C in vertisols. It is evident that better soil aggregation was recorded under NTSR90N could have a positive influence on soil C sequestration. Our results further highlight the importance of soil aggregation and aggregate‐associated C in relation to C sequestration. Copyright © 2016 John Wiley & Sons, Ltd.     

Aggregation and organic matter in subarctic Andosols under different grassland management

Quantity and quality of soil organic matter (SOM) affect physical, chemical, and biological soil properties, and are pivotal to productive and healthy grasslands. Thus, we analyzed the distribution of soil aggregates and assessed quality, quantity, and distribution of SOM in two unimproved and improved (two organic and two conventional) grasslands in subarctic Iceland, in Haplic and Histic Andosols. We also evaluated principal physicochemical and biological soil properties, which influence soil aggregation and SOM dynamics. Macroaggregates (>250 µm) in topsoils were most prominent in unimproved (62–77%) and organically (58–69%) managed sites, whereas 20–250 µm aggregates were the most prominent in conventionally managed sites (51–53%). Macroaggregate stability in topsoils, measured as mean weight diameter, was approximately twice as high in organically managed (12–20 mm) compared with the conventionally managed (5–8 mm) sites, possibly due to higher organic inputs (e.g., manure, compost, and cattle urine). In unimproved grasslands and one organic site, macroaggregates contributed between 40% and 70% of soil organic carbon (SOC) and nitrogen to bulk soil, whereas in high SOM concentration sites free particulate organic matter contributed up to 70% of the SOC and nitrogen to bulk soil. Aggregate hierarchy in Haplic Andosols was confirmed by different stabilizing mechanisms of micro- and macroaggregates, however, somewhat diminished by oxides (pyrophosphate-, oxalate-, and dithionite-extractable Fe, Al, and Mn) acting as binding agents for macroaggregates. In Histic Andosols, no aggregate hierarchy was observed. The higher macroaggregate stability in organic farming practice compared with conventional farming is of interest due to the importance of macroaggregates in protecting SOM and soils from erosion, which is a prerequisite for soil functions in grasslands that are envisaged for food production in the future.     

Habitat use and conservation of bumblebees (Bombus spp.) under different grassland management regimes

Declines in the natural populations of several bumblebee species across Britain and Europe are an increasing cause for concern. In this study the habitat use of bumblebees was investigated on Salisbury Plain Training Area, the largest remaining area of unimproved chalk grassland in north-west Europe. Habitat characteristics influencing the overall abundance, species richness and foraging activity of bumblebees included the diversity and abundance of flowering plant species (particularly of favoured forage plants such as Trifolium pratense), vegetation structure and height. It is suggested that different Bombus species respond to these habitat characteristics depending on their specific foraging and nesting requirements, the case of Bombus humilis being especially relevant. The effects of several grassland management practices were considered in terms of their suitability for the conservation of bumblebee habitats. Cattle grazing was shown to be preferable to both sheep grazing and the absence of any management, although the timing and intensity of such grazing was important. Small-scale disturbances caused by vehicle activity were also of value in producing locally abundant forage resources in less intensively managed grasslands.     

Wet sieving versus dry crushing: Soil microaggregates reveal different physical structure,bacterial diversity and organic matter composition in a clay gradient

Soil microaggregates contain particles of different sizes, which may affect their potential to store organic carbon (OC). A variety of methods can be used to isolate microaggregates from the larger soil structures, among which wet sieving approaches are widely employed. We developed a novel dry crushing method that isolates microaggregates along failure planes due to mechanical stresses rather than hydraulic pressures and compared the mechanical stability, OC contents and microbial community composition between dry-crushed and wet-sieved samples with contrasting clay contents. Dry-crushed samples exhibited a higher stability and bacterial diversity compared to wet-sieved samples. As a result, the dry-crushed microaggregates had different size distributions when analysed dry and after wetting. In the dry state, dry-crushed microaggregates were larger and contained more sand-sized primary particles within the aggregate structures. The wetting of dry-crushed aggregates caused a disintegration of larger microaggregates and sand-sized primary particles into smaller microaggregates that contained finer particles. In the soils with lower clay contents, the diameter of dry-crushed microaggregates was 40 μm larger due to more sand-sized primary particles remaining within the aggregates. Depending on how much volume in microaggregates is occupied by large primary particles, the OC concentration increased in the soil with higher clay content. Wet-sieved size fractions also showed a similar pattern of OC distribution, whereas more primary particles were observed outside of aggregates. Wet sieving approaches disperse the soil into OC-rich aggregates and might be preferable if OC dynamics are investigated. Differences in bacterial community composition in dependence on clay content were more pronounced in dry-crushed microaggregates. If intact aggregate architectures are of interest for the isolation of soil structural units, the presented dry crushing method might provide an advantageous alternative that also better preserves bacterial diversity.     

Soil aggregation,aggregate stability,organic carbon and nitrogen in different soil aggregate fractions under forest and shrub vegetation on the Loess Plateau,China

Revegetation has been reported as one of the most effective counter measures to reduce soil and water erosion on the Loess plateau in China. Soil aggregate stability and the distribution of organic carbon and nitrogen in different aggregate fractions would be affected by different plant communities. The objectives of this study were to elucidate the effects of different plant communities on soil aggregate stability and the distribution of organic carbon and nitrogen in different aggregate fractions in order to prove that the different plant covers enhance soil aggregate stability.     

Effects of Vermicompost Application on Soil Aggregation and Certain Physical Properties

Application of organic waste on agricultural land as a soil conditioner and fertilizing material has lately gained much attention. This study was conducted to determine the effects of vermicompost applications (0·5%, 1%, 2% and 4% w/w) on physical characteristics of soils with different textures (sandy loam, loam and clay), under laboratory conditions. The results indicated that in the higher soil aggregate fraction (>12·7 mm) aggregate fraction was limited at the three soils. Vermicompost applications in all three soils significantly increased organic matter content. When compared with control, the increasing rates in organic matter content were 14·0%, 23·8%, 42·0% and 90·2% for 0·5%, 1%, 2% and 4% vermicompost application doses, respectively. Vermicompost applications increased the wet aggregate stability and decreased the dispersion ratio of all the experimental soils in all aggregate size fractions. Overall, wet aggregate stability increased from 26·9% to 52·2% with the application rate of 4%. Correlation coefficient between organic matter content and wet aggregate stability was found as 0·918^**. The lowest mean bulk density and the highest mean total porosity occurred when the most vermicompost was added. In all the soils studied, the highest permeability coefficients were gained with the application dose of 2%. As a result of increase in wet aggregate stability and decrease in bulk density, air permeability increased, and penetration resistance decreased significantly. The results obtained in this study have clearly indicated that the vermicompost application is an effective way to improve soil physical characteristics. Copyright © 2015 John Wiley & Sons, Ltd.     

Soil organic carbon,nitrogen, and phosphorus distribution in stable aggregates of an Ultisol under contrasting land use and management history

Different land‐use affects the organization of mineral soil particles and soil organic components into aggregates and the consequent arrangement of the aggregates will influence essential ecosystem functions. We investigated a continuous rubber plantation (forested), land fallowed for 10 y (fallow), 10‐y continuous arable cropping land and cropped land with top soil removed (TSR) for concentrations of C, N, and P in bulk soil and dry aggregates. Results showed that a high level of soil disturbance decreased the proportion of surface (0–15 cm) soil aggregate stability (low mean weight diameter) in TSR by 149% and arable cropping by 125% compared with the forested. Aggregate associated SOC was higher in aggregate‐size fractions of forested land‐use when compared with that in 10‐y fallow, continuous arable cropping, and TSR. For aggregate associated N, fallow and forested land‐use types concentrated higher proportion across aggregate sizes than the arable cropping and TSR. Macro aggregate fractions generally contained higher concentrations of C, N, and P compared with the micro‐aggregates. Water transmission indicators like total porosity and saturated hydraulic conductivity recorded higher values with forested and fallow land‐use than the others. We can thus conclude that long‐term soil disturbance due to cultivation and removal of top soil reduces the accumulation of soil C, N, and P in bulk soil and decreases water transmission properties. On the other hand, aggregate‐associated C, N and P accumulations are dependent on the level of soil surface disturbance and aggregate sizes.     

Soil aggregate stability and aggregate-associated organic carbon under different land use or land cover types

Soil aggregate stability (SAS) is an indicator for soil condition and is greatly influenced by land use or land cover (LULC) type and other soil and environmental attributes. This study investigated the soil aggregate-size distribution, SAS, aggregate-associated organic carbon (AAOC) and the relative importance of factors affecting SAS and AAOC. Based on conditioned Latin hypercube sampling, soil aggregate samples were collected from the “A” horizon and wet sieved into large macroaggregates (>2.0 mm), small macroaggregates (0.25–2.0 mm), microaggregates (0.053–0.25 mm) and mineral fraction (<0.053 mm). The large macroaggregates accounted for 86% to 93% of the total aggregates under all LULC types except under dry land (64%) and paddy land (35%). The SAS under different LULC decreased in the order fir > shrubland > natural grassland > orchard > blue pine > broadleaf > mixed conifer > dry land > paddy land. The AAOC of the large macroaggregates constituted for 76%–90% of the total AAOC under all LULC types except under dry land (65%) and paddy land (38%). While SAS was largely influenced by the AAOC of small macroaggregates, microaggregates and large macroaggregates and LULC type, the AAOC of different aggregate fractions was mostly affected by LULC type, altitude and slope. SAS did not exhibit any significant relationship with the AAOC of different aggregate fractions under the natural LULC types but showed a strong relationship under the agricultural land indicating that AAOC is more critical for SAS under the agricultural land than under the natural LULC.     

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。     

伏牛山区迎河小流域不同土地利用类型的土壤粒径分布特征

为探讨伏牛山区坡耕地土壤物理性能的退化特征,在河南省鲁山县迎河小流域,利用激光粒度仪和土壤分形模型,比较分析了4种土地利用类型的土壤粒径分布(PSD)及其分形特征.研究结果表明:1)土壤PSD简单分维(Dv)以乔木林地最高(2.658),坡耕地最低(2.489),多重分维(容量维D0、信息维D1、关联维D2)以乔木林地最高(0.941、0.926、0.91),坡耕地最低(0.927、0.899、0.849).不同分形参数均表现为:坡耕地＜灌草坡地和水平梯田＜乔木林地;2)土壤PSD的Dv、D0、D1和D2,与黏粒和粉粒体积分数显著正相关,与砂粒体积分数显著负相关.因此,利用土壤PSD简单分形和多重分形维数,可量化表征土壤质地的粗细程度和非均匀性质的差别;坡耕地土壤质地的粗粒化程度和非均匀性明显大于其他土地利用类型;土壤细粒(黏粒和粉粒)物质流失是坡耕地土壤质地粗粒化和非均匀程度增大的重要原因.     

不同质地土壤上玉米养分吸收和分配特征

采用池栽试验在4种质地土壤和2种施肥水平下,研究了玉米植株氮、磷、钾的吸收和分配特征。结果表明,不同质地土壤上玉米植株养分累积量为氮钾磷;不同处理玉米氮、磷、钾的累积量表现为中壤轻壤粘壤砂壤,且各处理间差异达显著水平。不同处理叶片和茎鞘中三元素累积量的变化与单株一致,氮、磷、钾分配以叶片中的比例略高于茎鞘。从后期氮、磷、钾的转移率看,不同质地土壤表现为砂壤轻壤中壤粘壤;不同处理中子粒中氮、磷、钾的含量与产量变化一致,且处理间达显著水平。施肥增加了各种质地土壤上玉米植株及器官氮、磷、钾的累积量和子粒产量,其中砂壤增加幅度最大,轻壤和中壤次之,粘壤最小。同时施肥使得叶片和茎鞘中的氮、磷、钾转移率略有降低。     

Long‐term effects of soil management regimes on carbon contents and respiration rates of aggregate size fractions

This study investigated long‐term effects of soil management on size distribution of dry‐sieved aggregates in a loess soil together with their organic carbon (OC) and their respiratory activity. Soil management regimes were cropland, which was either abandoned, left bare fallow or cropped for 21 yr. Abandonment increased the abundance of macroaggregates (>2 mm) in the surface soil layer (0–10 cm) and reduced that of microaggregates (<0.25 mm) relative to Cropping, whereas the Fallow treatment reduced the abundance of macroaggregates at depths of 0–10 and 10–20 cm. All treatments yielded similar aggregate size distributions at a depth of 20–30 cm. The SOC content of aggregate size fractions in the surface soil from the Abandoned plots was greater (by 1.2–4.8 g/kg) than that of the corresponding fractions from the Cropped plots, but the opposite trend was observed in the subsurface soils. Conversely, the Fallow treatment reduced the SOC content of every aggregate size fraction. Smaller aggregates generally exhibited greater cumulative levels of C mineralization than larger ones. However, the bulk of the SOC losses from the soils via mineralization was associated with aggregates of >2 mm. Abandonment significantly increased the relative contribution of macroaggregates (>2 mm) to the overall rate of SOC loss, whereas the Fallow treatment significantly reduced the contribution of 0.25–2 mm aggregates to total SOC loss in the surface soil while substantially increasing their contribution in the subsurface soil.     

生物炭碳固定于稳定性土壤团聚体中：土壤黏土矿物及其它土壤性质的作用

Aggregation and structure play key roles in water-holding capacity and stability of soils.In this study,the incorporation of carbon(C) from switchgrass biochar into stable aggregate size fractions was assessed in an Aridisol(from Colorado,USA) dominated by 2:1 clays and an Alfisol(from Virginia,USA) containing weathered mixed 1:1 and 2:1 mineralogy,to evaluate the effect of biochar addition on soil characteristics.The biochar was applied at 4 levels,0,25,50,and 100 g kg~(-1),to the soils grown with wheat in a growth chamber experiment.The changes in soil strength and water-holding capacity using water release curves were measured.In the Colorado soil,the proportion of soil occurring in large aggregates decreased,with concomitant increases in small size fractions.No changes in aggregate size fractions occurred in the Virginia soil.In the Colorado soil,C content increased from 3.3 to 16.8 g kg~(-1),whereas in the53 μm fraction C content increased from 5.7 to 22.6 g kg~(-1) with 100 g kg~(-1)biochar addition.In the Virginia soil,C content within aggregate size fractions increased for each size fraction,except the2 000 μm fraction.The greatest increase(from 6.2 to 22.0 g kg~(-1)) occurred in the 53–250 μm fraction.The results indicated that C was incorporated into larger aggregates in the Virginia soil,but remained largely unassociated to soil particles in the Colorado soil.Biochar addition had no significant effect on water-holding capacity or strength measurements.Adding biochar to more weathered soils with high native soil organic content may result in greater stabilization of incorporated C and result in less loss because of erosion and transport,compared with the soils dominated by 2:1 clays and low native soil organic content.     

美国北阿巴拉契亚地区耕作措施和土地利用管理对土壤团聚体和有机碳的影响

Promoting soil carbon sequestration in agricultural land is one of the viable strategies to decelerate the observed climate changes.However,soil physical disturbances have aggravated the soil degradation process by accelerating erosion.Thus,reducing the magnitude and intensity of soil physical disturbance through appropriate farming/agricultural systems is essential to management of soil carbon sink capacity of agricultural lands.Four sites of different land use types/tillage practices,i) no-till (NT) corn (Zea mays L.) (NTC),ii) conventional till (CT) corn (CTC),iii) pastureland (PL),and iv) native forest (NF),were selected at the North Appalachian Experimental Watershed Station,Ohio,USA to assess the impact of NT farming on soil aggregate indices including water-stable aggregation,mean weight diameter (MWD) and geometric mean diameter (GMD),and soil organic carbon and total nitrogen contents.The NTC plots received cow manure additions (about 15 t ha-1) every other year.The CTC plots involved disking and chisel ploughing and liquid fertilizer application (110 L ha-1).The results showed that both water-stable aggregation and MWD were greater in soil for NTC than for CTC.In the 0-10 cm soil layer,the ＞ 4.75-mm size fraction dominated NTC and was 46％ more than that for CTC,whereas the ＜ 0.25-mm size fraction was 380％ more for CTC than for NTC.The values of both MWD and GMD in soil for NTC (2.17 mm and 1.19 mm,respectively) were higher than those for CTC (1.47 and 0.72 mm,respectively) in the 0-10 cm soil layer.Macroaggregates contained 6％42％ and 13％ 43％ higher organic carbon and total nitrogen contents,respectively,than microaggregates in soil for all sites.Macroaggregates in soil for NTC contained 40％ more organic carbon and total nitrogen over microaggregates in soil for CTC.Therefore,a higher proportion of microaggregates with lower organic carbon contents created a carbon-depleted environment for CTC.In contrast,soil for NTC had more aggregation and contained higher organic carbon content within water-stable aggregates.The soil organic carbon and total nitrogen stocks (Mg ha-1) among the different sites followed the trend of NF ＞ PL ＞ NTC ＞ CTC,being 35％-46％ more for NTC over CTC.The NT practice enhanced soil organic carbon content over the CT practice and thus was an important strategy of carbon sequestration in cropland soils.     

土壤水吸力空间分布规律的时间稳定性研究

该文分析了潘店乡（PDV,32 km2）和封丘站（FQS,0.05 km2）两个尺度下的土壤水吸力的时间稳定性,潘店乡布设39个测点,封丘站布设44个测点。每个测点埋设两根张力计,深度分别为20 cm和40 cm。PDV于2004年3月至5月共测定19次;FQS于2004年3月至7月共测定27次。研究结果表明：在这两个尺度下土壤水吸力都具有一定的时间稳定性,FQS明显优于PDV。灌溉对时间稳定性影响很大,土壤水吸力的稳定性在干湿交替时最差。PDV土壤水吸力的时间稳定性只在一个灌溉周期内存在,而FQS的时间稳定性可在整个灌溉周期、不同作物条件下持续。     

垄作小麦群体的光分布特征及其对不同叶位叶片光合速率的影响

利用4个不同基因型小麦(Triticum aestivum L.)品种(大穗型品种"烟辐188"和"淄麦12"、多穗型品种"济麦22"和"济麦20")对比研究了垄作和传统平作两种栽培方式对小麦群体内部光分布特征及其对不同叶位叶片光合速率的影响.结果表明:垄作栽培方式显著改善了小麦冠层内光的垂直分布状况,使冠层内不同垂直高度的光照强度显著高于传统平作,并显著提高了小麦冠层内不同叶位叶片的光合速率;垄作栽培能够显著降低多穗型小麦品种冠层温度,而对大穗型小麦品种作用不明显;垄作栽培方式能够显著提高多穗型小麦品种归一化植被指数(NDVI),明显改善小麦生长状况;垄作栽培方式可显著提高小麦的千粒重,增加穗粒数,使小麦的行优势得到充分发挥.垄作栽培方式更适合分蘖成穗率较高、群体相对较大的多穗型品种.     

不同土地利用方式下土壤团聚体的组成及稳定性研究

采用野外调查与室内分析相结合的方法.就不同土地利用方式下土壤团聚体的组成及稳定性进行了研究.试验结果表明:(1)干筛处理下土壤团聚体均以>5 mm粒径为主,总体随粒径的减小呈先降低后增加再降低的趋势;湿筛处理下土壤团聚体以<0.25 mm粒径为主,总体随粒径的减小呈先降低后增加的趋势.(2)干筛处理下,平均重量直径和几何平均直径均表现为桉树人工林最大,杉木人工林最小;湿筛处理下平均重量直径和几何平均直径均以杉木人工林最大,枇杷园最小.(3)风干性团聚体的分形维数表现为杉木人工林>茶园>枇杷园>桉树人工林>撂荒地,水稳性团聚体的分形维数表现为枇杷园>撂荒地>茶园>桉树人工林>杉木人工林.     

不同施肥模式下设施菜田土壤团聚体养分和微生物量特征

【目的】针对设施蔬菜生产中普遍存在的化肥施用严重超量、化肥与有机肥配施模式不合理等现象,利用日光温室蔬菜有机肥/秸秆替代化肥模式定位试验,研究了不同施肥模式对设施菜地土壤团聚体养分、微生物量碳氮含量的影响,为设施蔬菜优质高效生产和减量施用化肥提供科学依据。【方法】将25%或50%的无机氮肥用玉米秸秆或猪粪中氮替代,进行温室蔬菜田间定位试验。试验共设5个处理(各处理等氮、等磷、等钾):1)全部施用化肥氮(4/4CN);2) 3/4化肥氮+1/4猪粪氮(3/4CN+1/4MN);3) 2/4化肥氮+2/4猪粪氮(2/4CN+2/4MN);4) 2/4化肥氮+1/4猪粪氮+1/4秸秆氮(2/4CN+1/4MN+1/4SN);5) 2/4化肥氮+2/4秸秆氮(2/4CN+2/4SN)。在定位试验第6年冬春茬黄瓜季拉秧期采取耕层土壤样品,分析土壤团聚体分布规律和稳定性,并测定各粒级团聚体中土壤养分和微生物量碳、氮含量。【结果】设施菜地土壤团聚体以250~1000μm团聚体和> 2000μm团聚体为主,其含量分别平均为32.0%和38.4%。较4/4CN模式,有机肥/秸秆替代化肥模式提高了土壤大团聚体(> 250μm)比例。配施秸秆模式对土壤团聚体分布影响相对较大,并显著提高土壤团聚体机械稳定性,平均重量直径(MWD)和平均几何直径(GMD)分别提高6.1%和11.2%。在<250μm团聚体、250~1000μm团聚体、1000~2000μm团聚体和> 2000μm团聚体中,不同有机肥化肥配施模式(3/4CN+1/4MN、2/4CN+2/4MN、2/4CN+1/4MN+1/4SN、2/4CN+2/4SN)土壤有机碳含量较4/4CN模式分别增加36.8%~89.6%、34.9%~100.3%、29.5%~69.2%和21.7%~72.1%,分别平均增加69.8%、76.6%、56.9%和49.2%。不同施肥模式对有机碳、全氮、硝态氮、速效磷的影响规律基本一致。土壤有机碳、全氮主要分布在250~1000μm团聚体和> 2000μm团聚体中,平均分别占土壤有机碳储量的34.1%、35.2%和土壤全氮储量的34.0%、36.4%。土壤硝态氮在250~1000μm团聚体与1000~2000μm团聚体中含量较高,土壤速效钾、微生物量碳氮含量表现为随土壤团聚体直径的增大而提高,而速效磷则随土壤团聚体直径的增大而降低。【结论】设施菜田土壤团聚体优势粒级为> 2000μm团聚体和250~1000μm团聚体,配施秸秆模式显著提高土壤团聚体的机械稳定性。有机肥/秸秆替代化肥模式提高土壤各级团聚体有机碳、全氮、硝态氮和速效磷含量。设施菜地土壤有机碳氮主要分布在250~1000μm团聚体和> 2000μm团聚体中,而微生物量碳、氮含量随土壤团聚体直径的减小而呈增加的趋势。