利用栽培技术提高夏秋茶品质研究初探

夏秋季节气温高、日照强,茶树体内碳代谢水平相对较高,氮代谢水平相对较低,从而造成夏秋茶多酚类物质含量较高,氨基酸含量偏低,制成的绿茶苦涩味重,口感差,清香缺乏,品质远远不及春茶,因而使得一些茶厂对夏秋茶少采甚至不采,造成了茶园经济效益降低,茶叶总产量减少。文章就茶园栽培管理技术方面如何提高夏秋茶利用率及品质作一定的总结,以期对提高夏秋茶品质有所帮助。     

走进犍为“世界茉莉博览园”

正茉莉[Jasminum sambac (L.)Ait]为木樨科素馨属直立或攀援灌木,全世界约有200余个品种,我国约有60个品种。茉莉按花冠的层数可分为三大类,即:单瓣茉莉,花冠单层;双瓣茉莉,花冠两层;多瓣茉莉,花冠两层以上。四川省乐山市犍为县的茉莉花(茶),以品质优良而著称。犍为县近年来围绕大力发展茉莉茶特色主导产业,壮大茉莉茶全产业链的目标,推出了"四     

速溶六堡茶的不同生产工艺及其品质测定

利用不同的生产工艺对六堡茶进行提取分离并将其制成速溶茶粉,通过对茶粉感官指标评审和理化成分分析研究生产工艺对茶粉品质的影响,从而确定最优的速溶六堡茶粉的生产工艺。最优的速溶六堡茶粉提取工艺为原茶按照1:8的料液比例,60℃的水温2次浸提,采用膜浓缩与冷冻干燥相结合的制取工艺。所制得的速溶六堡茶得率较高,且基本保持了原茶风味。     

建设生态茶果园 加快治理水土流失

泉州市人多地少，为促进农村经济发展，发挥区位优势，应大力开发山地种植茶果。但由于水土保持意识淡薄，加上资金儿技术的限制，造成广种薄收和水土流失的现象相当严重，这一状况巳严重制约着农村产业结构调整。因此要加快治理茶果园的水土流失，建设生态茶果园，达到茶果园土地资源的永续利用，提高茶果单产和品质，应对我国加入WTO对农业提出的挑战。     

夏秋茶品质提升技术研究现状及发展趋势

针对目前春季名优茶畅销、夏秋茶滞销的现象,收集并总结了夏秋茶品质提升方面的研究现状,探讨了夏秋茶品质提升中存在的问题,并指出了3个方面的发展趋势.     

两株芽孢杆菌对茶用菊红心菊生长和品质的影响

为探讨从不同品种菊花根际土壤中分离的两株芽孢杆菌对茶用菊生长和品质的影响,以茶用菊红心菊为试验材料,研究对照(CK)、接种解淀粉芽孢杆菌处理(Ba)、接种枯草芽孢杆菌处理(Bs)、接种解淀粉芽孢杆菌和枯草芽孢杆菌混合处理(Ba+Bs)对茶用菊红心菊各生育期生理指标的影响。结果表明,苗期菌剂对各生理指标的促生效果显著高于生长期和花期;花期时,菌剂接种处理均不同程度地促进了茶用菊红心菊收获时品质和产量的提高,其中绿原酸、木犀草苷、3,5-二咖啡酰基奎宁酸含量与CK相比平均提高20%左右,且三组接种菌剂处理之间无显著差异,而Ba+Bs处理后红心菊的黄酮含量最高,比CK提高15.64%,同时该处理红心菊的估产量也最高,比CK、Ba和Bs分别提高了152.00%、64.12%和33.61%。综上所述,在茶用菊苗期栽培土壤中混合接种解淀粉芽孢杆菌和枯草芽孢杆菌(Ba+Bs)可以显著提高红心菊外观品质、花期产量以及茶用品质。本研究结果为今后茶用菊功能微生物有机肥研发奠定了良好的基础。     

丘陵茶园不同机采方式对秋季茶鲜叶产量和名优绿茶品质的影响

经过连续4年的田间试验, 比较了2次机采、重度机采、轻度机采和不机采对照等4个处理对白露毛尖茶产量和品质的影响.结果表明: 2次机采和重度机采处理显著增加秋季茶芽密度和1芽1叶初展鲜叶产量, 显著降低单个芽头的平均重量、长度及符合加工白露毛尖茶芽大小标准的茶芽合格率; 符合加工白露毛尖茶芽大小标准的1芽1叶初展鲜叶产量轻度机采处理最高; 内含成分分析表明, 4个处理秋季1芽1叶初展鲜叶均适宜加工白露毛尖茶, 以不机采对照处理感官品质最好.试验表明适度机采可提高秋季白露毛尖茶鲜叶产量, 不机采或轻度机采可获得更多优质的白露毛尖茶鲜叶原料.     

干燥工艺对重庆沱茶原料茶贮藏品质的影响

试验比较了不同干燥方式的沱茶原料茶在常温密封贮藏1年过程中的品质变化规律。结果表明:1)4号茶样亮度(L*值)、茶汤绿度(a*值)下降缓慢,黄度(b*值)升高较慢;2)4号茶样叶绿素含量变化平缓,茶多酚和咖啡碱减幅及氨基酸增幅虽不及5号茶样,但均显著超越其他茶样;3)1, 2, 6, 7号茶样感官品质显著降低,3, 4, 5号茶样感官品质较稳定,其中,4号茶样感官品质显著优于3, 5号茶样,日晒味显著减弱,并透有栗香,滋味更醇厚,叶底更明亮。4号茶样呈现较优的耐贮藏性能,此工艺既能提升感官品质、形成独特风味,又能替代传统沱茶原料茶加工工艺,从而提高工效和安全性能。     

便携式茶鲜叶品质光谱检测装置研制

品质监测对茶鲜叶适时采摘和茶叶加工品控具有重要意义。该研究基于可见/近红外光谱技术,研发了便携式茶鲜叶品质无损检测装置。该装置分为主机和手柄2部分,主机大小约240 mm×250 mm×240 mm,包括光谱仪、光源、可充电锂电池、稳压板和散热风扇;手柄大小约130 mm×100 mm×30 mm,包括光纤探头、金属灯杯、白参考板和外触发按钮。基于该设备,采集了茶鲜叶500～900 nm范围内可见/近红外漫反射光谱,对比了归一化（Normalize,NOR）、一阶导数（First Derivative,FD）、标准正态变量变换（Standard Normal Variable Transformation,SNV）和概率商归一化（Probabilistic Quotient Normalization,PQNOR）等不同光谱预处理方法对茶叶光谱的处理结果,建立了茶鲜叶干物质含量、水浸出物含量、茶多酚含量的偏最小二乘定量预测模型。结果表明,PQNOR预处理后建立的偏最小二乘预测模型精度最好,干物质、水浸出物和茶多酚含量预测模型在验证集的相关系数分别为0.905、0.896和0.747,均方根误差分别为0.856%、0.559%和0.549%。在茶园对装置的精度进行了现场测试,单片茶鲜叶检测时间约为1 s,干物质、水浸出物和茶多酚含量预测值与测量值的均方根误差分别为0.903%、0.634%和0.551%。该装置可以实现茶鲜叶光谱原位采集和干物质含量、水浸出物、茶多酚的定量分析,对及时掌握茶树生长情况、辅助决策采茶方案和保障茶叶品质具有重要作用。     

基于改进YOLOv5网络的复杂背景图像中茶尺蠖检测

茶叶的产量和品质深受病虫害的影响。茶尺蠖是一种常见的茶叶害虫,精确检测茶尺蠖对茶叶病虫害防治有重要意义。由于茶尺蠖和茶树枝、枯死茶叶的颜色、纹理相近,茶尺蠖的体积小、形态多变、被遮挡等问题,现有方法检测茶尺蠖的精度不高。该研究提出一种基于深度学习的复杂背景图像中茶尺蠖检测方法,该方法使用YOLOv5为基线网络,利用卷积核组增强对茶尺蠖的特征提取,在不增加计算量的条件下减少复杂背景对茶尺蠖检测结果的干扰;使用注意力模块关注茶尺蠖整体,根据茶尺蠖的大小和形状自适应调节感受野,降低因目标大小形状不一导致的漏检;使用Focal loss损失函数减少前景和背景的类不平衡对检测结果的影响。试验结果表明,所提方法用于复杂背景图像中茶尺蠖的检测,可以达到0.94的召回率,0.96的精确度和92.89%的平均精度均值。与基线网络相比,该方法的平均精度均值提高了6.44个百分点。使用相同的数据集和预处理的对比分析表明,该方法优于SSD、Faster RCNN和YOLOv4等其他经典深度学习方法,平均精度均值比SSD、Faster RCNN、YOLOv4分别高17.18个百分点、6.52个百分点和4.78个百分点。该方法可实现对茶尺蠖的智能检测,减少人力成本,有助于实现精准施药,提高茶叶的产量和品质。     

Genetic resource enhancement by isolation of diversegenotypes from seed progeny in predominantly sterile rose scentedgeranium Pelargonium graveolens

Four new accessions (BSP1-4) of rose scentedgeranium Pelargonium graveolens were derivedfrom the spontaneous half-sib seed progeny of mostly sterilepopulations of the cultivar accession Bipuli. The seed producingplants of Bipuli had been growing among the populations of cultivaraccessions Hemanti and Kunti in the temperate agroclimate ofKodaikanal, Tamilnadu in India. The four new accessions were comparedwith the cultivar accessions Bipuli, Hemanti and Kunti in fieldexperiments under subtropical agroclimate of Lucknow, Uttar Pradeshfor essential oil yield and quality related traits and in terms oftheir RAPD profiles. The crop yield and essential oil parameters andDNA profiles of the four new accessions and three cultivar accessionsallowed the conclusion that the accessions BSP-1, BSP-2 andBSP-3 were Bipuli × Kunti hybrids and BSP-4was a Bipuli × Hemanti hybrid. The accession BSP-4demonstrated hybrid vigour in several of the essential oil yieldrelated traits; on average basis it out yielded other accessions by afactor of about 2.4. The essential oil of BSP-4 had 89%rhodinol content in which citronellol to geraniol ratio was 1:1 andthe contents of isomenthone, menthone, 10-epi--eudesmol, 6,9-guaiadiene, decanoic acid andisodecanoic acid were relatively lower than in the oils of accessionsBipuli and/or Hemanti. The present study has shown a way for thegeneration of new genotypes in rose scented geranium in which thecultivars have been vegetatively maintained for decades and thegenetic resources are scanty.     

Long-Term Organic Amendment Application Improves Influence on Soil Aggregation,Aggregate Associated Carbon and Carbon Pools under Scented Rice-Potato-Onion Cropping System after the 9th Crop Cycle

A field experiment was conducted to investigate the influence of long-term application of organic manures on aggregate stability, associated carbon concentrations and carbon pools as an important soil-quality parameter under a scented rice-potato-onion cropping system in silt-loam textured soil in Eastern Bihar, India (subtropical climatic condition). Five treatments were used: 1) nitrogen, phosphorus and potassium (NPK) – 100% recommended dose of NPK; 2) NPK+FYM (farmyard manure) – 50%NPK+50% N as FYM; 3) FYM+VC (vermicompost)+ NC (neem cake) – different organic sources each equivalent to 1/3 of the recommended N (FYM +VC +NC); 4) FYM+VC+NC+PSB (phosphate-solubilizing bacteria – different organic sources each equivalent to 1/3 of the recommended N (FYM +VC+NC)+biofertilizers containing N and P carriers (PSB) and 5) FYM+BFN+BM+PSB – 50% N as FYM + biofertilizer for N +Bone meal to substitute P requirement of crops + PSB. The aggregate size distribution (>250 μm) at different soil depths is higher in treatment FYM+VC+NC+PSB and is at par with FYM+VC+NC, followed by FYM+BFN+BM+PSB and NPK+FYM, and the lowest in treatment receiving 100% NPK. The mean carbon concentration in each soil fraction was higher in soil depth 0–10 cm, followed by 10–20 cm and 20–30 cm. The trend of mean weight diameter (MWD) in different treatments was FYM+VC+NC+PSB ≥ FYM+VC+NC > NPK+FYM > FYM+BFN+BM+PSB > NPK. The trend of carbon concentrations in different treatments was FYM+VC+NC+PSB ≥ FYM+VC+NC > FYM+BFN+BM+PSB ≥ NPK+FYM > NPK. Non-labile pool of carbon forms the major portion (60.14%) of the total soil organic carbon (SOC) irrespective of all depths. Bulk density (BD) has a significant role in stabilizing soil aggregates as well as increasing the SOC content in soil. SOC was negatively correlated with BD (r = ?0.870, p = 0.05), MWD (r = ?0.911, p = 0.01) and geometric mean diameter (GMD) (r = ?0.958, p = 0.05) irrespective of depth. This study took further steps toward understanding the enhancing of aggregate stability on organic manures addition for soil quality improvement.     

Effect of Soil Sodicity on Growth,Yield, Essential Oil Composition,and Cation Accumulation in Rose‐Scented Geranium

Abstract

The effect of soil sodicity [exchangeable sodium percentage (ESP)] on the growth, yield, essential oil composition, and cation accumulation of two cultivars (Bourbon and Cimpawan) of geranium (Pelargonium graveolens) were studied in a pot experiment. Irrespective of soil sodicity, two cultivars of geranium differed significantly in their plant height and herb and oil yield. Plant height was not significantly affected with increases in soil ESP from 0.7 (control) to 20.0 and 7.0, respectively, for cultivars (cv) Bourbon and Cimpawan, but further increase in soil ESP decreased the plant height. The herb yield of cv Bourbon significantly increased with increasing soil ESP to 16.0, and the oil yield increased with increasing ESP to 7.0. Further increase in soil ESP decreased the yield. The increase in yield of cv Bourbon was 13.1 and 15.1% in the herb and 40.0 and 15.2% in the oil over the control (ESP 0.7) at soil ESP of 7.0 and 16.0, respectively. Decreases in yield were 3.5, 4.9, 53.3, and 59.3% in the herb yield and 3.8, 5.7, 53.3, and 80.0% in the oil over control (ESP 0.7) at soil ESP of 20.0, 24.0, 28.0, and 30.0, respectively. The herb and oil yield of cv Cimpawan significantly decreased with increase in soil ESP. The decease in yield was 17.7, 20.2, 40.7, 53.1, 70.7, and 72.6% in the herb and 4.0, 6.8, 30.9, 45.4, 83.2, and 84.0% in the oil over control (soil ESP 0.7) at the soil ESP 7.0, 16.0, 20.0, 24.0, 28.0, and 30.0, respectively. The concentration of isomenthone, linalool, citronellyl formate, and geranyl formate in the essential oil increased at low levels of soil ESP (between 16.0 to 24.0) but decreased at high soil ESP (>28). The concentration of l‐citronellol, nerol, and geraniol gradually increased with increase in soil ESP. The increase in the soil ESP enhanced the concentration of sodium (Na) and decreased that of potassium (K) in shoot and root tissues of geranium as compared to control. The concentration of Ca in shoot tissues of cv Bourbon significantly decreased with increase in soil ESP, but in the cv Cimpawan, the Ca concentration was not significantly affected with increase in soil ESP from 0.7 to 16.0, and thereafter the Ca concentration significantly decreased with further increase in soil ESP. The concentration of Na, K, and Ca were relatively higher in shoot than in root tissues. The K/Na and Ca/Na ratios in shoot tissues of both cultivars of geranium decreased with increase in soil ESP. The K/Na and Ca/Na ratios in shoot were not found to be related to the differences in sodicity tolerance of the cultivars of geranium tested in this experiment. The concentration of zinc (Zn) in shoot tissues decreased with increase in soil ESP. The cv Bourbon maintained a higher concentration of Zn in shoot tissues at high sodicity than that of cv Cimpawan. The results suggest that the geranium is slightly to moderately tolerant of soil sodicity stress.     

Exploration, collection and characterisation of Basmati rice germplasm in India

Eighty-eight long, slender, scented Basmati rice germplasms were collected from North India during an exploration mission. Morpho-agronomic characterisation of the accessions revealed a significant variability in leaf length, culm length, culm number and panicle length.     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Biodiversity and ecogeography of wild Lactuca spp. in some European countries

Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions.     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.     

Properties of anaerobically digested and composted municipal solid waste assessed by linking soil mesofauna dynamics and nitrogen modelling

We have studied the effect of anaerobically digested (ADMSW) and composted municipal solid waste (CMSW) on mineralization and foodweb dynamics to verify the hypothesis that ADMSW would immobilize N right after addition to soil in contrast to addition with CMSW. Another hypothesis was that the mesofauna (enchytraeids and microarthropods) would stimulate N release from the decomposer community. We measured excretion of -N and urea-N from the mesofauna and hypothesized that enchytraeids would release urea. ADMSW and CMSW were amended to pots with sandy loam and barley. The pots were divided into treatments with or without mesofauna. Mesofauna, plant N and biomass, soil N and ergosterol (fungal biomass) were measured over a 113-day period of four equidistant samplings. Soil respiration, N mineralization and N release by the mesofauna were modelled from concurrent studies. ADMSW- and CMSW-treated soils initially (<20 days) immobilized N. The amendments did not increase plant growth substantially, and this was probably due to N-limitation in the early stages of plant growth. Enchytraeid abundance was about three times higher in ADMSW- than CMSW-treated soils, indicating that ADMSW contained more labile compounds, bacteria, and microfauna. The mesofauna did not affect N-content, but the cumulated -N excreted by the mesofauna was estimated to be substantial and about one-fifth of total plant N in ADMSW. An explanation for this discrepancy might be that in the absence of the mesofauna, other members of the detrivore and microbivore community performed the mesofauna’s function. Neither enchytraeids nor microarthropods excreted urea.