The Maturity and CH4, N2O,NH3 Emissions from Vermicomposting with Agricultural Waste

This study investigated the maturity and gaseous emissions from vermicomposing with agricultural waste. A vermicomposting treatment (inoculated Eisenia fetida) was conducted over a 50-day period, taking tomato stems as the processing object and using cow dung as the nutrient substrate. A thermophilic composting treatment without earthworm inoculation was operated as a control treatment. During the experiment, maturity indexes such as temperature, pH, C/N ratio, and germination index (GI) were determined and continuous measurements of earthworm biomass and CH₄, N₂O, and NH₃ emissions were carried out. The results showed that the temperature during vermicomposting was suitable for earthworm survival, and the earthworm biomass increased from 10.0 to 63.1 kg m^?3. Vermicomposting took less time on average to reach the compost maturity standard (GI 80%), and reached a higher GI (132%) in the compost product compared with the thermophilic composting treatment. Moreover, the decrease of the C/N ratio in vermicompost indicated stabilization of the waste. The activities of earthworms played a positive role in reducing gaseous emissions in vermicompost, resulting in less emissions of NH₃ (12.3% NH₃-N of initial nitrogen) and total greenhouse gases (8.1 kg CO₂-eq/t DM) than those from thermophilic compost (24.9% NH₃-N of initial nitrogen, 22.8 kg CO₂-eq/t DM). Therefore, it can be concluded that vermicomposting can shorten the period required to reach compost maturity, can obtain better maturity compost, and at the same time reduce gaseous emissions. As an added advantage, the earthworms after processing could have commercial uses.     

稻秸蚯蚓堆制后的物理、化学及微生物特性变化

利用水稻秸秆与畜禽粪便（牛粪、猪粪和鸡粪）等干重混合物（RCD、RPM、RCE）接种蚯蚓（Eisenia foetida）进行堆制,研究堆肥产物的物理、化学及微生物特性变化。结果表明,蚯蚓堆制30 d后,稻秸牛粪、稻秸猪粪堆肥产物MBC含量显著下降; 3种稻秸粪便混合物经蚯蚓堆制后,堆肥产物微生物代谢熵、脱氢酶和碱性磷酸酶活性增加,尤以RCD的变化明显。稻秸牛粪、稻秸猪粪及稻秸鸡粪混合物经蚯蚓堆制后,总固形物平均重量损失分别增加6.45%、4.22%和3.82%; pH值均降低,其中RCD显著降低。蚯蚓堆制有助于提高堆肥产物全氮、全磷和全钾含量,同时使碳氮比降低。水稻秸秆混入部分畜禽粪便经蚯蚓堆制可减少堆肥时间并提高堆肥质量,混入的粪便以牛粪最好,猪粪次之,鸡粪最差。     

蚯蚓-蚯蚓粪分离-收获工艺与关键部件试验

蚯蚓堆肥是实现农业有机固体废弃物减量化、无害化、资源化和增值化的生物处理技术之一。蚯蚓堆肥结束后,如何将成熟活体蚯蚓从大量堆肥物料中快速分离收获,是目前规模化蚯蚓堆肥亟需解决的难题之一。为实现蚯蚓体快速、高效、稳定的分离和收获,该研究提出了蚯蚓堆肥产物3步分离收获工艺方法,并针对此工艺中的动态斜面分离收获关键部件和工艺参数开展了试验研究。在此基础上,结合力学分析、EDEM离散元仿真模拟揭示了蚯蚓分离关键过程中的动力学机制。结果表明：本研究所提出的分离工艺可较好实现蚯蚓、蚯蚓粪的分离和集中收获,动态斜面在蚯蚓-蚯蚓粪分离过程中起关键作用,利用了蚯蚓体表液膜接触粘附摩擦特性强,易粘附于斜面,而动态斜面作用下蚯蚓粪滚动摩擦力小的特性,蚯蚓与蚯蚓粪抛落于动态斜面后因受力差异导致两者呈相反方向运动,实现分离。蚯蚓-蚯蚓粪分离收获的最优参数组合为安装锥形分离器下,分离收获斜面速度50 mm/s、倾角为30°。基于此工艺方法处置蚯蚓粪-蚯蚓混合物料10 kg耗时55.36 s,在蚯蚓收获区的蚯蚓收获率为（81.50±5.55）%,蚯蚓粪含杂率接近于0,物料总收获率为（96.56±1.79）%。研究结果可提高蚯蚓堆肥产物分离收获的速度与效率,为规模化蚯蚓堆肥机械装备化、减少人工作业和降低成本提供借鉴与参考。     

Effects of Adding Nitrogen to Vermicompost on Tomato Seedlings Under Greenhouse Conditions

Vermicompost, a byproduct of earthworm digestion of organic solid waste is receiving attention as a peat substitute in the production of plug seedling media. We aimed to test the effects of adding nitrogen to vermicompost on the morphological development of tomato seedlings. Nursery experiments on tomato seedlings were carried out in the greenhouse. Urea at 0.00 kg/m³, 0.25 kg/m³, 0.50 kg/m³, and 1.00 kg/m³ was added to vermicompost and to the vermicompost-vermiculite (at a volume ratio of 4:1) mixture. Results showed that (1) Nitrogen application at different rates to the vermicompost significantly increased the strong seedling index (SSI) at the middle (T1) and late (T2) seedling growth stages. Besides, nitrogen application significantly increased concentrations of available nitrogen (available-N) at the beginning of seedling cultivation (T0) and nitrate nitrogen (NO₃^?-N) at T2 in vermicompost. (2) Adding nitrogen to vermicompost significantly increased the number of root tips at T1 and T2 and the root volume at T2. And it significantly decreased the electrical conductivity (EC), total N (TN), available N, ammonium N (NH₄⁺-N), and NO₃^?-N at T1 and T2. (3) Adding nitrogen to the vermicompost-vermiculite mixture significantly increased the root/shoot ratio, and SSI at T1 and T2. And it significantly increased the pH and reduced the EC at T1 and the available-N, NH₄⁺-N, and NO₃^?-N at T2. In short, adding nitrogen (0.5～1.0 kg/m³ urea) to vermicompost improved the shoot and root morphological development of tomato seedlings, as well as the biomass accumulation and allocation. Adding nitrogen to the vermicompost-vermiculite mixture further promoted the development of tomato seedlings.     

Responses of Saline Soil Properties and Cotton Growth to Different Organic Amendments

Application of organic waste to saline alkaline soils is considered to be a good practice for soil remediation. The effects of applying different organic amendments (e.g., cattle dung, vermicompost, biofertilizer) and earthworm inoculations (Eisenia fetida) on saline soils and cotton growth were investigated during 1 year of cotton cultivation. Compared to the control (applied with inorganic NPK fertilizer), applying organic amendments improved soil physicochemical properties. Biofertilizer application improved available nutrient content, reduced short-term soil electrical conductivity, and produced the highest cotton yield, whereas cattle dung and vermicompost applications resulted in higher soil organic matter content. Application of organic amendments significantly increased soil microbial biomass carbon during the flowering period, which sharply declined at harvest. This was especially true for the biofertilizer treatment, which also exhibited lower nematode abundance compared with the other organic materials. Earthworm inoculation following cattle dung application failed to significantly change soil physicochemical properties when compared to the treatments without earthworm inoculation. Results suggest that biofertilizer application to saline soil would improve soil nutrient status in the short-term, whereas cattle dung application would improve soil organic matter content and increase soil organism abundance to a greater extent. However, different strategies might be required for long-term saline soil remediation.     

Effects of Epigeic Earthworms on Decomposition of Wheat Straw and Nutrient Cycling in Agricultural Soils in a Reclaimed Salinity Area:A Microcosm Study

Earthworms,one of the most important macroinvertebrates in terrestrial ecosystems of temperate zones,exert important influences on soil functions.A laboratory microcosm study was conducted to evaluate the influence of the earthworm Eisenia fetida on wheat straw decomposition and nutrient cycling in an agricultural soil in a reclaimed salinity area of the North China Plain.Each microcosm was simulated by thoroughly mixing wheat straw into the soil and incubated for 120 d with earthworms added at 3 different densities as treatments:control with no earthworms,regular density(RD)with two earthworms,and increased density(ID)with six earthworms.The results showed that there was no depletion of carbon and nitrogen pools in the presence of the earthworms.Basal soil respiration rates and metabolic quotient increased with the increase in earthworm density during the initial and middle part of the incubation period.In contrast,concentrations of microbial biomass carbon and microbial biomass quotient decreased in the presence of earthworms.Earthworm activity stimulated the transfer of microbial biomass carbon to dissolved organic carbon and could lead to a smaller,but more metabolically active microbial biomass.Concentrations of inorganic nitrogen and NO₃^--N increased significantly with the increase in earthworm density at the end of the incubation(P<0.05),resulting in a large pool of inorganic nitrogen available for plant uptake.Cumulative net nitrogen mineralization rates were three times higher in the ID treatment than the RD treatment.     

Influence of earthworm activity and rice straw application on the soil microbial community structure analyzed by PLFA pattern

The earthworm Pheretima hilgendorfi, one of the most common anecic species in Japan, abounds in soils with applied rice-straw residues. The influences of the worm’s activity and/or those of rice-straw application on the soil microbial community structure were studied using a microcosm approach. Low Humic Andosol was incubated with or without earthworms in a jar for a month after the following treatments: 1) no treatment, 2) chopped rice straw top-dressed on the soil and 3) rice straw incorporated into the soil. The soil NO₃^–-N level increased with the earthworms’ presence even in the soil without rice straw. The soil NH₄⁺-N level was by far the highest in the soil treated with worms and no rice straw. Amounts of total and bacterial PLFAs increased due to the earthworms’ presence when rice straw was incorporated. The proportion of unsaturated fatty acids increased in the earthworm treatment while the saturated fatty acids decreased, suggesting an increase in the Gram-negative bacterial proportion. The results of principal component analysis indicated that the rice straw and the earthworms affected the soil microbial community structure independently. Any direct influence of the PLFAs contained in the worms’ bodies and in the rice straw on the soil’s PLFA profile was thought to be small.     

Quantification of nitrogen excretion rates for three lumbricid earthworms using 15N

 Nitrogen excretion rates of ¹⁵N-labeled earthworms and contributions of ¹⁵N excretion products to organic (dissolved organic N) and inorganic (NH₄-N, NO₃-N) soil N pools were determined at 10  °C and 18  °C under laboratory conditions. Juvenile and adult Lumbricus terrestris L., pre-clitellate and adult Aporrectodea tuberculata (Eisen), and adult Lumbricus rubellus (Hoffmeister) were labeled with ¹⁵N by providing earthworms with ¹⁵N-labeled organic substrates for 5–6 weeks. The quantity of ¹⁵N excreted in unlabeled soil was measured after 48 h, and daily N excretion rates were calculated. N excretion rates ranged from 274.4 to 744 μg N g^–1 earthworm fresh weight day^–1, with a daily turnover of 0.3–0.9% of earthworm tissue N. The N excretion rates of juvenile L. terrestris were significantly lower than adult L. terrestris, and there was no difference in the N excretion rates of pre-clitellate and adult A. tuberculata. Extractable N pools, particularly NH₄-N, were greater in soils incubated with earthworms for 48 h than soils incubated without earthworms. Between 13 and 40% of excreted ¹⁵N was found in the ¹⁵N-mineral N (NH₄-N+NO₃-N) pool, and 13–23% was in the ¹⁵N-DON pool. Other fates of excreted ¹⁵N may have been incorporation in microbial biomass, chemical or physical protection in non-extractable N forms, or gaseous N losses. Earthworm excretion rates were combined with earthworm biomass measurements to estimate N flux from earthworm populations through excretion. Annual earthworm excretion was estimated at 41.5 kg N ha^–1 in an inorganically-fertilized corn agroecosystem, and was equivalent to 22% of crop N uptake. Our results suggest that the earthworms could contribute significantly to N cycling in corn agroecosystems through excretion processes. Received: 12 April 1999     

Influence of earthworm culture on fertilization potential and biological activities of vermicomposts prepared from different plant wastes

The present investigation was aimed to analyze influence of earthworm culture on nutritive status, microbial population, and enzymatic activities of composts prepared by utilizing different plant wastes. Vermicomposts were prepared from different types of leaves litter of horticulture and forest plant species by modified vermicomposting process at a farm unit. Initial thermophilic decomposition of waste load using cow‐dung slurry was done in the separate beds. The culture of Eisenia fetida was used for vermicomposting in specially designed vermibeds at the farm unit. The physico‐chemical characteristics, enzyme activities (oxido‐reductases and hydrolases), and microbial population (bacteria, fungi, free‐living nitrogen‐fixing bacteria, actinomycetes, Bacillus, Pseudomonas, phosphate‐solubilizing bacteria and fungi) of vermicomposts were found significantly higher (p < 0.05) than those of control (without earthworm inoculum). The study quantified significant contributions of earthworm culture to physico‐chemical, enzymatic, and microbiological properties of vermicompost and confirmed superior fertilization potential of vermicompost for organic farming. The agronomic utility of vermicompost was assessed on yellow mustard plant in a pot experiment. Pot soil was amended with different ratios (5%, 10%, 20%) of vermicompost and normal compost (without earthworm inoculum). Effects of these amendments on the growth of Brassica comprestis L. were studied. The significant differences (p < 0.05) in the growth of plant were observed among vermicompost‐, compost‐amended soil, and control. Vermicompost increased the root and shoot lengths, numbers of branches and leaves per plant, fresh and dry weights per plant, numbers of pods and flowers, and biochemical properties of plant leaf significantly, especially in 20% amendment. These results proved better fertilization potential of vermicompost over non‐earthworm‐inoculated compost.     

Survival of Aporrectodea caliginosa and its effects on nutrient availability in biosolids amended soil

Few earthworms are present in production agricultural fields in the semi-arid plains of Colorado, where earthworm populations may be constrained by limited water and/or organic matter resources. We conducted a 12-week laboratory incubation study to determine the potential of a non-native endogeic earthworm (Aporrectodea caliginosa) to survive in a low-organic matter Colorado soil (1.4% organic C content), supplemented with or without biosolids, and to determine the effects of A. caliginosa on soil microbial biomass and soil nutrient availability. A factorial design with three main effects of A. caliginosa, biosolids addition, and time was used. Data was collected through destructively sampling at one, two, four, eight, and twelve weeks. During the 12-week study, 97.5% of the worms in the soil survived, and the survival of the earthworms was not significantly affected by the addition of biosolids. The addition of biosolids, however, did significantly reduce the gain in mass of the earthworms (8% mass gain compared to 18% in soil without biosolids). The presence of A. caliginosa significantly increased soil NH₄-N, and NO₃-N concentrations by 31% and 4%, respectively, which was less than the six fold increases in both soil NH₄-N, and NO₃-N concentrations supplied from biosolids. Microbial biomass carbon was not affected by A. caliginosa, but microbial biomass N was affected by an earthworm × biosolids interaction at week 1 and 12. We concluded that A. caliginosa can survive in a low-organic matter Colorado soil under optimal moisture content and that once established, A. caliginosa can provide modest increases in inorganic N availability to crops Colorado agroecosystems.     

C and N turnover of fermented residues from biogas plants in soil in the presence of three different earthworm species (Lumbricus terrestris,Aporrectodea longa,Aporrectodea caliginosa)

A soil microcosm experiment was performed to assess (1) the C- and N- turnover of residues from biogas plants in soils in the presence of three earthworm species (Lumbricus terrestris, Aporrectodea longa and Aporrectodea caliginosa) and (2) the resulting changes in soil chemical and microbiological properties when using these residues as fertilizer in comparison to conventional slurry. Earthworms were exposed in soils, fertilized with an equivalent amount of 120 kg of NH₄-N ha^?1 from: (1) conventional cattle slurry and (2) a fermented residue derived from cattle slurry, grass (silage) and maize. Additional treatments without slurry and earthworms were used as controls.There was considerable evidence that soils fertilized by fermented slurry comprised fewer amounts of readily available nutrients for microbial C and N turnover. We observed significant stimulation of microbial biomass, basal respiration and nitrification in treatments with conventional slurry, especially in the presence of earthworms. However, the stimulation of microbial activity by manure and earthworms were significantly lower in treatments with fermented slurry. Moreover, the results showed clear interactions between different earthworm species and manures. While the biomass of the anecic species (L. terrestris and A. longa) increased in both slurry treatments, the biomass of A. caliginosa (endogeic) decreased, with a significantly stronger biomass decline in treatments with fermented slurry. The metabolic quotients revealed microbial stress metabolism in fermented slurry treatments, predominantly in treatments with A. caliginosa. We conclude that particularly A. caliginosa and soil microorganisms competed for labile C sources in treatments with fermented slurry. An application of these residues as fertilizer might result in a reduction of microbial activity in agricultural soils and in a decline of endogeic earthworms.     

Organic resources and earthworms affect phosphorus availability to sorghum after phosphate rock addition in semi-arid West Africa

A field experiment was laid out in Burkina Faso (West Africa) on an Eutric Cambisol to investigate the interaction of organic resource quality and phosphate rock on crop yield and to assess the contribution of earthworms (Millsonia inermis Michaelsen) to P availability after phosphate rock application. Organic resources of different quality were applied at a dose equivalent to 40 kg N ha^–1 with or without phosphate rock from Kodjari (Burkina Faso) at a dose equivalent to 25 kg P ha^–1, and were compared with control and single phosphate rock treatments in a factorial complete block design with four replicates. Sorghum (Sorghum bicolor L. Moench) variety SARIASSO 14 was grown. Sheep dung had the highest impact on earthworm casting intensity followed by maize straw. Combining organic resources with phosphate rock reduced earthworm casting activities compared to a single application of organic resources or phosphate rock. Addition of phosphate rock to maize straw reduced P availability in earthworm casts whereas combining sheep dung or compost with phosphate rock increased P availability. The contribution of earthworms to Kodjari phosphate rock solubilisation mainly occurred through their casts, as the available P content of casts was 4 times higher than that of the surrounding soil.     

不同光照条件下蚯蚓避光性运动与蚓粪机械化分离参数量化

蚯蚓和蚯蚓粪的机械化分离是目前蚯蚓规模化养殖业亟需解决的瓶颈问题之一,针对目前最常用的蚯蚓光分离工艺方法在实际养殖分离中全凭人为经验、效率低、无机械化参数等问题,探究了不同光质条件:白光、黄光、绿光、蓝光、红光、白炽灯光在10~270 lx不同光照强度下,对照实际自然环境场景:室内光照、室外阴处光照和太阳光直射光照条件下的蚯蚓避光应激行为,并结合光线辐射在蚯蚓粪多孔介质内的衰减规律分析了蚯蚓堆肥物料表层一定之内厚度无蚯蚓的原因。结果表明:光照强度10 lx时,蚯蚓不受光照影响;光照强度10~30 lx时,蚯蚓的避光反应显现;光照强度30~210 lx时,蚯蚓的避光应激程度随着光照强度增加缓慢加强,消失时间不断缩短;光照强度210 lx时,光照引起的蚯蚓的避光反应程度趋于最大。白光和太阳光引起蚯蚓避光反应最显著,蚯蚓蠕动消失时间分别为6.5和5 min,蚯蚓消失5 min后堆料表层无蚯蚓层厚度在10~15 mm之间。蚯蚓对红色光应激程度极低,平均消失时间20 min;除了红光,随着光照强度增加,蚯蚓在堆料表面的消失时间呈现对数曲线趋势下降。该研究量化分析了蚯蚓对光质、光照强度的应激响应时间,以期为蚯蚓养殖分离,机械自动化逐层、定时、定量、定光强分离表层蚯蚓粪提供工艺参数。     

Influence of agricultural intensification on the earthworm community in arable farmland in the North China Plain

Two field experiments had been conducted in Huantai County, Shandong Province, east of China, with an effort to understand the impact of agricultural intensification on earthworm diversity and population density. Seven species of earthworms were identified in the two experiments. Average earthworm populations in the higher fertility soil (experiment B, 1.83% organic matter) were relatively abundant, with a population density of 105 indiv./m² and biomass of 57 g/m². Aporrectae trapezoids was the most dominant species. In the lower fertility soils (experiment A, 1.43% organic matter) the population density was only 51 indiv./m² and the average biomass was 30 g/m². Drawida gisti was the most dominant species. For both the experiments A and B, organic fertilizer (OF) and crop straw return increased earthworm abundance. The impact of chemical fertilizer (CF) on the earthworm population was found to depend on the amount of organic input. In experiment B, the earthworm biomass decreased when only winter wheat (Triticum aestivum) straw was input at three CF application levels. However, while both winter wheat straw (WS) and corn (Zea mays) stalk returned, there was no negative correlation between CF and earthworm density and biomass.     

Biological weathering of phlogopite during enriched vermicomposting

As the dominant macrofauna in many soils, earthworms play a significant role in mineral weathering and nutrient release from mineral structures into available forms for root uptake. Phlogopite is a trioctahedral micaceous mineral that can be weathered to other minerals through release of its interlayer potassium (K). In this study, we investigated the effect of earthworm activities and associated microbial communities on phlogopite weathering during the production of phlogopite-enriched vermicompost with different quantities of phlogopite added. An experiment was run under laboratory conditions using three levels of phlogopite (0, 20% and 40% by weight) in triplicates. Each Petri dish contained 20 g of a mixture of cow manure and phlogopite, and vermicomposting process was performed by inoculation of eight Eisenia foetida earthworms. Changes in clay mineralogy and C/N ratio in each dish were assessed at days 0, 45, 90, 135, and 180 during vermicomposting. The results indicated that phlogopite was partially weathered to vermiculite and interstratified mica-vermiculite during the vermicomposting process. The rate of weathering was higher during the early stages of vermicomposting (the first 90 d). The weathering of phlogopite was influenced considerably by the activity of earthworms and associated microbial communities during the organic matter transformation process. At the early stages of the process, the weathering rate for different levels of phlogopite was not significantly different, but over time it accelerated steadily, and the difference increased.     

Earthworm regulation of nitrogen pools and dynamics and marker genes of nitrogen cycling: A meta-analysis

Earthworms, as the ecosystem engineers, both directly and indirectly affect the nitrogen(N) cycle. We aimed to provide a quantitative assessment of the contribution of earthworms to the terrestrial ecosystem N cycle using meta-analysis of 130 publications selected. The natural logarithm of the response ratio(lnRR) was used to indicate the effect size of earthworms on N dynamic variables. The results showed that earthworms significantly affected soil N-cycling microorganisms, including the amoA gene abundance of soil ammonia-oxidizing bacteria(AOB), and significantly promoted soil N cycle processes,including denitrification, mineralization, and plant assimilation. The effects of earthworms on the N cycle were experimental design dependent and affected by factors such as the functional group of earthworm and residue input. The presence of the anecic earthworms decreased the rates of mineralization and nitrification, and increased nitrification and denitrification responses were more pronounced in the presence of the endogeic earthworms than that of the other two functional groups of earthworms. In addition, residue input enhanced the effects of earthworms on the N cycle. The effects of earthworms on nitrous oxide(N₂ O) emission increased when residues were added. These findings indicate that residue input and introducing suitable functional groups of earthworms into the field can lead to N sustainability without increasing N2 O emission. This meta-analysis also provides systematic evidence for the positive effects of earthworms on the plant N pool, N availability(soil ammonium(NH₄⁺) content), and soil microbial biomass N content, showing the potential to alter ecosystem functions and services in relation to N cycling.     

Effect of climate, soil type and earthworm activity on nitrogen transfer from a nitrogen-15-labelled decomposing material under field conditions

 N transfer from ¹⁵N-labelled decomposing material into the microbial biomass and inorganic N forms was studied for more than 2 years at three experimental sites differing in climatic conditions and earthworm abundance. The ¹⁵N-labelled decomposing material was mixed with low-elevation soil (LES), mid-elevation soil (MES) and high-elevation soil (HES). The amended soils were put into two kinds of plastic cylinders closed on both sides with nets preventing (0.1 cm mesh) and allowing (0.5 cm mesh) access by earthworms, and were buried in soil (20 cm depth) to monitor the transfer of N from the ¹⁵N-labelled decomposing material. Climate and soil type play an important role in the release of N from decomposing material. LES transplanted to more humid sites (mid- and high-elevation sites) showed an increase in most of its biological activities (N atom % excess, and microbial biomass C and N). Furthermore, LES was a sandy soil in which the ¹⁵N-labelled decomposing material was less bound than in MES and HES, which contained more silt and clay. This resulted in faster organic matter turnover when climatic conditions were favourable. The presence of earthworms greatly increased the quantity of inorganic N (mainly NH₄ ⁺) in the soils and enhanced the release of N from the ¹⁵N-labelled decomposing material and the native organic matter, compared to soil without earthworms. Received: 21 January 1999     

间伐对杉木人工林土壤碳氮及其组分特征的影响

为探究不同间伐强度对杉木人工林土壤碳氮及其组分特征的影响,以福建省三明市官庄国有林场11年生杉木(Cunninghamia lanceolata)人工林为研究对象,采用弱度间伐(LIT)、中度间伐(MIT)、强度间伐(HIT)等3种间伐强度,研究不同间伐强度林分0—10,10—20,20—40,40—60,60—80,80—100 cm土层总有机碳(SOC)、全氮(TN)及易氧化有机碳(ROC)、硝态氮(NO_3~--N)、铵态氮(NH_4~+-N)、微生物量碳(MBC)、微生物量氮(MBN)、微生物熵碳(qMBC)、微生物熵氮(qMBN)的变化特征,以探讨不同间伐强度对杉木人工林土壤碳氮及其组分特征的影响。结果表明:间伐降低了土壤SOC和TN的含量,降低幅度分别为1.4%～36.9%,3.1%～45.7%。间伐增加了土壤MBC、NO_3~--N的含量,而对ROC、NH_4~+-N和MBN的程度在不同土层有差异,qMBC和qMBN随着间伐强度的增加而增大。相关性分析表明,土壤SOC分别与TN、qMBC、ROC、NH_4~+-N、MBC、MBN呈极显著正相关(P0.01);TN与qMBN、ROC、NH_4~+-N、MBC、MBN呈极显著正相关(P0.01)。杉木人工林间伐处理降低了土壤表层SOC和TN含量,增加了土壤SMBC和qMBC、qMBN,同时也增加了土壤表层(0—10 cm)SMBN。抚育间伐导致土壤SOC和TN含量降低主要是由于活性碳、氮含量的增加,提高土壤中有机质分解速率,最终导致土壤SOC和TN含量降低。     

Reproduction Efficiency of Eisenia foetida and Substrate Changes During Vermicomposting of Organic Materials

ABSTRACT

Vermicomposting is the processing of organic substrates through digestion by worms, usually Eisenia foetida. The physico-chemical characteristics of the substrates and health of the worms are important parameter for effective vermicomposting. This study assessed reproduction efficiency and reproductive rate of E. foetida and changes in EC, pH, organic C, total Nitrogen and C:N ratio by vermicomposting different substrate mixtures. The study was performed as a completely randomized design with 10 treatments and 4 replicates. Manures from sheep and horse were tested alone and mixed at 50 and 75% with residues of alfalfa and wheat straw. Wheat straw was also tested alone and mixed at 75% with 25% chicken manure. E. foetida were added to the mixtures and allowed to process the substrate mixtures for three months. Final EC, pH, organic C and N levels of vermicompost were measured, as well as the reproductive efficiency and reproductive rate of the E. foetida. All measured characteristics of the finished vermicompost were significantly different depending on substrate. Substrates also changed to differing degrees during vermicomposting. Total C and EC increased in all substrates; and pH, total N, and C:N decreased in all substrates during vermicomposting The greatest change of EC was in the 25% alfalfa + 75% sheep manure mixture, which was 12.8 dS.m-1 initially and 18.6 dS.m-1 in finished vermicompost. Overall, pH declined and EC increased during the preparing of vermicompost.     

The influence of livestock dung on the abundance of exotic and native earthworms in a grassland in south-eastern Australia

It is well known that organic matter in the form of dung is utilised as a food source by some earthworms, but little has been reported on the preferences of earthworms for different types of dung in agricultural settings. An experiment was carried out in spring in south-eastern Australia to evaluate the effect that dung from different livestock has on the abundance of earthworms in a grassland environment. We were particularly interested to compare the responses of native Australian earthworms (Megascolecidae) with those of exotic earthworms (Lumbricidae and Acanthodrilidae). The attractiveness of dung from sheep, cattle and horses was measured by determining the abundance and biomass of the resident earthworm species under each dung type at varying times after adding the dung to the soil surface (0, 10, 20 and 30 days). The earthworm population consisted of three exotic species, Apporrectodea trapezoides, Microscolex dubius and M. phosphoreus, and two native species, Spenceriella macleayi and S. bywongensis. Both the number of days that the dung was available to earthworms and the type of dung influenced the numbers and biomass of the earthworms found beneath the dung pats. Significant interactions existed between time and dung type when all adult earthworms were considered as one group and also when adults were split into individual species. The various species responded differently to the dung, but horse dung was generally the more preferred dung type. The significance of these results is discussed in terms of the management of dung in an Australian pastoral context.