不同饲养密度对鳝苗的生长性能研究     

包淋斌 《江西水产科技》2014,(4):7-9

本试验以水蚯蚓作为饵料,研究了60日龄鳝苗不同密度下的增重、存活率及饵料转化率。试验分3个密度组,其对应的密度分别为2000尾/m2、3000尾/m2、4000尾/m2,每个密度组设4个平行;试验时间为30d。结果表明:在本试验条件下,3个密度组鳝苗的增重率、存活率随着密度的增大呈下降趋势,而其饵料系数随着密度增大而增大;其中在4000尾/m2的密度下,鳝苗的增重率最低,仅为1.12±0.13;饵料系数最高,为5.71±1.37。  相似文献   

Impact of soil engineering by two contrasting species of earthworms on their dispersal rates     

《Applied soil ecology》2014

By burrowing galleries and producing casts, earthworms are constantly changing the structure and properties of the soils in which they are living. These changes modify the costs and benefits for earthworms to stay in the environment they modify. In this paper, we measured experimentally how dispersal behaviour of endogeic and anecic earthworms responds to the cumulative changes they made in soil characteristics. The influence of earthworm activities on dispersal was studied in standardised mesocosms by comparing the influence of soils modified or not modified by earthworm activities on earthworm dispersal rates.The cumulative use of the soil by the earthworms strongly modified soil physical properties. The height of the soil decreased over time and the amount of aggregates smaller than 2 mm decreased in contrast to aggregates larger than 5 mm that increased. We found that: (i) earthworm activities significantly modified soil physical properties (such as bulk density, soil strength and soil aggregation) and decreased significantly the dispersal rates of the endogeic species, whatever the species that modified the soil; (ii) the decreasing in the dispersal proportion of the endogeic species suggests that the cost of engineering activities may be higher than the one of dispersal; (iii) the dispersal of the anecic species appeared to be not influenced by its own activities (intra-specific influences) or by the activities of the endogeic species (inter-specific influences). Overall these results suggest that the endogeic species is involved in a process of niche construction, which evolved jointly with its dispersal strategy.  相似文献   

Earthworms increase soil microbial biomass carrying capacity and nitrogen retention in northern hardwood forests     

《Soil biology & biochemistry》2015

Earthworms have been shown to produce contrasting effects on soil carbon (C) and nitrogen (N) pools and dynamics. We measured soil C and N pools and processes and traced the flow of ¹³C and ¹⁵N from sugar maple (Acer saccharum Marsh.) litter into soil microbial biomass and respirable C and mineralizable and inorganic N pools in mature northern hardwood forest plots with variable earthworm communities. Previous studies have shown that plots dominated by either Lumbricus rubellus or Lumbricus terrestris have markedly lower total soil C than uncolonized plots. Here we show that total soil N pools in earthworm colonized plots were reduced much less than C, but significantly so in plots dominated by contain L. rubellus. Pools of microbial biomass C and N were higher in earthworm-colonized (especially those dominated by L. rubellus) plots and more ¹³C and ¹⁵N were recovered in microbial biomass and less was recovered in mineralizable and inorganic N pools in these plots. These plots also had lower rates of potential net N mineralization and nitrification than uncolonized reference plots. These results suggest that earthworm stimulation of microbial biomass and activity underlie depletion of soil C and retention and maintenance of soil N pools, at least in northern hardwood forests. Earthworms increase the carrying capacity of soil for microbial biomass and facilitate the flow of N from litter into stable soil organic matter. However, declines in soil C and C:N ratio may increase the potential for hydrologic and gaseous losses in earthworm-colonized sites under changing environmental conditions.  相似文献   

Earthworm biomass response to soil management in semi-arid tropical Alfisol agroecosystems     

M. Vikram Reddy  V. P. Kiran Kumar  V. Ravinder Reddy  P. Balashouri  D. F. Yule  A. L. Cogle  L. S. Jangawad 《Biology and Fertility of Soils》1995,19(4):317-321

Earthworms recorded during 1989–1993 across 15 soil management treatments, comprising three different tillagexthree organic amendments (bare, farmyard manure, and rice straw) and six perennial ley treatments, belonged to two endogeic species, Octochaetona phillotti (Michaelsen) and Lampito mauritii Kinberg, while in a nearby undisturbed natural revegetation area three species were found, including the above two and Octonochaeta rosea (Stephenson). The earthworm biomass showed significant temporal and spatial variations and was higher during the post monsoon period than in the early rainy season. No worm biomass was recorded during the dry season. In the tillage and organic amendment treatments, the biomass was drastically reduced from September 1989 to September 1991 after the application of carbofuran and some herbicides, and was significantly reduced during these two years compared to that of 1992. The maximum monthly earthworm biomass ranged between 2.5 and 17.9 g m^-2 across the treatments and increased several-fold in the nearby natural revegetation area (75.9 g m^-2). It significantly increased in perennial ley treatments compared to annual treatments with organic amendments. Thus the earthworm biomass varied significantly (P<0.01) across the 15 treatments, indicating discernible effects of soil management.Visiting Scientist (under the Rockefeller Foundation Environmental Research Fellowship in International Agriculture)  相似文献   

Earthworm channels in cultivated clayey and loamy Norwegian soils     

Tore E. Sveistrup  Trond Knapp Haraldsen  Freddy Engelstad 《Soil & Tillage Research》1997,43(3-4)

Studies of earthworm species and their activity, expressed as channels, on cultivated loamy (Humic Cryaquept) and clayey soils (Typic Endoaqualf and Typic Cryaquept) were conducted in southern and central Norway before conversion from conventional to organic cropping systems. At all the three study areas: Landvik (Grimstad), Voll (Ås) and Kvithamar (Stjørdal), the earthworm species Aporrectodea caliginosa, Aporrectodea rosea, Allolobophora chlorotica and Lumbricus rubellus were found. At Landvik, where the deep-burrowing species Aporrectodea longa, A. caliginosa and Lumbricus terrestris dominated, medium (4–6 mm) and coarse (>6 mm) earthworm channels were most numerous below the plough layer. Almost no coarse pores were found at Voll and Kvithamar. The volume of earthworm channels below the plough layer was 0.6–0.8% of total soil volume at Landvik and Voll and 0.3–0.4% at Kvithamar. Earthworm channels >6 mm below the plough layer were useful to identify present and previous activity of deep-burrowing earthworms such as L. terrestris. Below the plough layer, roots were almost entirely restricted to earthworm channels and interaggregate spaces.  相似文献   

Moisture conservation for rainfed wheat production with alternative mulches and conservation tillage in the hills of north-west India   总被引：3，自引：0，他引：3  

C. L. Acharya  O. C. Kapur  S. P. Dixit 《Soil & Tillage Research》1998,46(3-4):153-163

In the hills of north–west India, maize (Zea mays L.)-wheat (Triticum aestivum L.) is the dominant cropping system. However, rainfed wheat suffers from lack of optimum moisture at sowing. Field experiments were conducted for 3 years on a silty clay loam (Typic Hapludalf) to evaluate the effectiveness of mulches and conservation tillage for rainfed wheat in mitigating this problem. The treatments were ten factorial combinations of five mulch-tillage practices and two nitrogen levels (N₆₀ and N₁₂₀ kg ha⁻¹). Mulch treatments consisted of application of 10 Mg ha⁻¹ (dry weight basis), to previous standing maize, of either wild sage (Lantana camara L.) or eupatorium (Eupatorium adenophorum Sprengel) in combination with either conventional or conservation (minium) tillage prior to wheat sowing. These alternative practices were compared to the conventional farmer practice of soil tillage after harvest of maize with no mulch. The application of these weed mulches to standing maize maintained friable soil structure owing to a five fold higher mean population of earthworms underneath mulch. Mulches resulted in 0.06–0.10 m³ m⁻³ higher moisture in the seed-zone when wheat was sown compared with the conventional farmer practice of soil tillage after maize harvest. Mulch-conservation tillage treatments favourably moderated the hydro-thermal regime for growing a wheat crop. The mean root mass density under these treatments at wheat flowering was higher by 1.27–1.40 times over the conventional farmer practice during the 3 year study. Conservation tillage holds promise because it does not require elaborate tillage and may ultimately reduce animal draught in the hilly regions. Recycling available organic materials having no fodder value coupled with conservation tillage may help enrich the soil environment in the long-term. The practice also offers gainful use of these obnoxious weeds that cause great menace in grass and forest lands in the region.  相似文献   

接种蚯蚓对潮土氮素矿化特征的影响   总被引：2，自引：0，他引：2  

刘宾  李辉信  朱玲  焦加国  陈小云  胡锋 《土壤学报》2007,44(1):98-105

在室内恒温（20℃）培养，间歇破坏性采样（于培养后第2、6、13、20、27、41、55天采样）的条件下，研究蚯蚓活动对土壤中氮素矿化特征的影响。共设置4个处理：（1）对照处理-不接种蚯蚓不添加秸秆（S）；（2）仅接种蚯蚓不添加秸秆处理（E）；（3）不接种蚯蚓仅添加秸秆处理（O）；（4）接种蚯蚓并添加秸秆处理（0E）。结果表明：在整个培养时期中，仅接种蚯蚓处理（E）的土壤铵态氮和硝态氮含量均较对照处理（S）有显著提高（P〈0．05），分别较同期对照处理（S）高出0．54-5．71倍和0．04-2．01倍；接种蚯蚓添加秸秆处理（OE）的土壤中的铵态氮含量较同期仅添加秸秆处理（0）增高了0．42-7．26倍，并达到显著性差异（P〈0．05），但两处理的硝态氮含量无显著性差异（P〉0．05）。从整体水平来看，无论是否添加秸秆，接种蚯蚓处理（E，OE）的土壤矿质氮水平均较相应的对照处理（S，O）有显著提高（P〈0．05），到培养55d时，分别增加了1．93倍和2．36倍。仅接种蚯蚓处理（E）的土壤氮素矿化速率和累积矿化速率较对照处理（S）有显著提高（P〈0．05）；添加秸秆后，无论是否接种蚯蚓，土壤累积矿化速率均为负值，表现为对土壤矿质氮的净固定，而从土壤氮素矿化速率的变化来看，前期的各个时间段中主要表现为矿质氮的净固定，后期逐渐表现为一定程度的矿化。此外，仅接种蚯蚓处理（E）的全氮含量除了培养2d外，其他培养时期均与对照处理（S）有显著差异（P〈0．05），到培养55d时，其全氮含量较同期对照处理（S）增高了6．55％。相关性分析结果表明，在仅接种蚯蚓处理（E）中，培养前后蚯蚓鲜重的减少量与土壤全氮含量之间存在极显著正相关（P〈0.01），根据一元线性方程将蚯蚓损失的鲜重换算为蚯蚓体损失的氮量后发现，在整个培养期中蚯蚓体本身排泄的氮大约占土壤全氮含量增加量的百分比为42％-100％。  相似文献   

Isotopic detection of recent photosynthate carbon flow into grassland rhizosphere fauna     

N. Ostle  P. Ineson  P. Staddon 《Soil biology & biochemistry》2007,39(3):768-777

In this study, we measured the incorporation of recent photosynthate-C inputs into active rhizosphere fauna (earthworms, enchytraeids, mites and collembolans) in an upland grassland soil under natural environmental conditions. This was achieved by means of a ¹³CO₂ pulse-chase experiment made during the growing season, followed by a 20-day dynamic sampling of soil fauna for ¹²C/¹³C analysis by IRMS. The effect of post-¹³C labelling defoliation (cutting) on fauna ¹²C/¹³C ratios was also examined.Results showed that earthworms made up over 93% of the extracted fauna biomass, while mites, collembolans and enchytraeids together accounted for less than 7%. All fauna groups showed evidence of tracer ¹³C in their tissues within a week of ¹³CO₂ pulse labelling in both control and cut treatments. Cutting significantly increased the amount of tracer ¹³C entering the organisms (P=0.0002). Similarly, the fauna group also had a significant effect (P=0.0001). Time did not have any effect on fauna ¹³C content between groups as differences were only significant at the last sampling occasion. The interaction time×animal group, however, had a significant effect (P=0.0054).Collembolans accounted for most of the tracer ¹³C measured within the fauna biomass, i.e. mean±standard deviation of 44.78±12.75% and 44.29±14.69% of fauna ¹³C in control and cut treatments, respectively. Mites and earthworms contained between 22.13% and 28.45%, and enchytraeids less than 6% of the tracer ¹³C. We conclude that, during the growing season, there was a rapid incorporation of recent photosynthate-C into rhizosphere mesofauna. This carbon transfer was most significantly increased by defoliation in mites and collembolans (P<0.01). These results provide evidence that soil foodweb carbon dynamics are not solely underpinned by detrital decomposition but are also affected by short-term plant rhizodeposition patterns.  相似文献   

接种蚯蚓及植物促生根际细菌对甘蓝生长·营养元素吸收的影响     

吴福勇  毕银丽  毛艳丽 《安徽农业科学》2012,40(10):5912-5914

[目的]为阐明混合接种蚯蚓及植物促生根际细菌技术在蔬菜生产中的作用。[方法]采用室内盆栽试验的方法,研究接种蚯蚓、植物促生根际细菌(固氮细菌和钾活化细菌)对甘蓝生长的影响以及甘蓝对氮和钾的吸收。[结果]7种接种方式均明显促进了甘蓝根上部分的生长,其中混合接种蚯蚓、固氮细菌和钾活化细菌处理下甘蓝根上部分生物量最大。5种接种方式(接种蚯蚓、双接蚯蚓和固氮细菌、双接蚯蚓和钾活化细菌、双接钾活化细菌和固氮细菌以及混合接种)下甘蓝地上部分氮的吸收量在0.05水平显著高于对照。[结论]混合接种方式是一种有潜力的生物技术,可以用来减少蔬菜生产中化肥的施用量。  相似文献   

Effects of liming on survival and reproduction of two potentially invasive earthworm species in a northern forest Podzol     

《Soil biology & biochemistry》2013

During the last several decades, colonization of soil by exotic earthworms and their effects on soil properties and biodiversity have been reported in forests of North America. In some northern hardwood stands, acid soils or harsh climate may have prevented earthworm colonization. However, climatic change and the increasing use of liming to restore the vigor of declining sugar maple (Acer saccharum Marsh.) stands, situated on base-poor soils in USA and Canada, could make many of these sites more suitable for earthworm colonization. We tested survival and reproduction of two exotic earthworm species (Lumbricus terrestris and Amynthas hawayanus) in unlimed and limed soils at the northern limit of the northern hardwood forest distribution in Canada. Improving soil parameters of base-poor, acidic soils by liming positively influenced activity, survivability and reproductive output of L. terrestris in this northern hardwood forest. In contrast, the high mortality and low vigor of L. terrestris observed in the unlimed plots show that soils in this area with a pH of 4.3 are not favorable to this species. Our results suggest that A. hawayanus was very active prior to winter at both soil pHs, but was not able to complete its life cycle during one year at this latitude. Both earthworm species significantly reduced organic C and total N, and increased the C/N ratio of the forest floor. Given that forest liming activities are increasing in proximity to human activities, there is high probability that some earthworm species, such as L. terrestris, will invade limed northern hardwood forests in the next decades, with possible consequences for soil organic matter turnover, nutrient cycling and forest biodiversity and dynamics.  相似文献