bluuebunny/crossref_metadata_2025_split huggingface dataset:
The ultrastructure of the spermathecae in the Collembola Symphypleona (Hexapoda)
Authors: Dallai Romano , Zizzari Zaira Valentina , Fanciulli Pietro Paolo 
Published: June 2008

AbstractThe fine structure of the paired spermathecae of two Symphypleona Collembola, Sminthurus viridis and Allacma fusca, was studied. The spermathecal epithelium is rich in pigment granules, while secretory organelles are scarce, consisting of a few mitochondria and microtubules, scattered cisterns of endoplasmic reticulum and Golgi systems. Small isolated secretory granules are visible in the apical cell region, where irregular microvilli are present. Beneath the epithelium, large cells rich in endoplasmic reticulum and Golgi systems are present; they are separated from the epithelial cells by a thin basal lamina. The epithelium is lined by a thin cuticle, which forms thin extensions at the beginning of the spermathecal duct. At this level, muscle fibers are visible. The spermathecal lumen is filled with many spermatozoa. At molting, the spermathecal epithelial cells detach from the cuticle and a large electron‐transparent space is evident between the cytoplasm and the cuticle. The cytoplasm has few pigment granules and the spermathecal lumen contains degenerating spermatozoa. After 3 days, the spermathecal epithelium regains its usual appearance and the spermathecal lumen is empty. The two species of Collembola Symphypleona do not have accessory glands. Compared with the Arthropleona Orchesella villosa, which has a single spermatheca and two accessory glands (Dallai et al. 2008 J Morphol 269:464–478), a great difference has occurred in the organization of the female genital system of these species. The results are discussed in light of the implications for reproductive behavior and egg protection in Symphypleona. J. Morphol., 2008. © 2008 Wiley‐Liss, Inc.
Extraction of mobile element fractions in forest soils using ammonium nitrate and ammonium chloride
Authors: Schöning Alexander , Brümmer Gerhard W. 
Published: June 2008

AbstractThe extraction of earth alkaline and alkali metals (Ca, Mg, K, Na), heavy metals (Mn, Fe, Cu, Zn, Cd, Pb) and Al by 1 M NH4NO3 and 0.5 M NH4Cl was compared for soil samples (texture: silt loam, clay loam) with a wide range of pH(CaCl2) and organic carbon (OC) from a forest area in W Germany. For each of these elements, close and highly significant correlations could be observed between the results from both methods in organic and mineral soil horizons. The contents of the base cations were almost convertible one‐to‐one. However, for all heavy metals NH4Cl extracted clearly larger amounts, which was mainly due to their tendency to form soluble chloro complexes with chloride ions from the NH4Cl solution. This tendency is very distinct in the case of Cd, Pb, and Fe, but also influences the results of Mn and Zn. In the case of Cd and Mn, and to a lower degree also in the case of Pb, Fe, and Zn, the effect of the chloro complexes shows a significant pH dependency. Especially for Cd, but also for Pb, Fe, Mn, Zn, the agreement between both methods increased, when pH(CaCl2) values and/or contents of OC were taken into account. In comparison to NH4Cl, NH4NO3 proved to be chemically less reactive and, thus, more suitable for the extraction of comparable fractions of mobile heavy metals. Since both methods lead to similar and closely correlated results with regard to base cations and Al, the use of NH4NO3 is also recommended for the extraction of mobile/exchangeable alkali, earth alkaline, and Al ions in soils and for the estimation of their contribution to the effective cation‐exchange capacity (CEC). Consequently, we suggest to determine the mobile/exchangeable fraction of all elements using the NH4NO3 method. However, the applicability of the NH4NO3 method to other soils still needs to be investigated.
Trends in grain yields and soil organic C in a long‐term fertilization experiment in the China Loess Plateau
Authors: Fan Tinglu , Xu Minggang , Song Shangyou , Zhou Guangye , Ding Linping 
Published: June 2008

AbstractChanges in grain yields and soil organic carbon (SOC) from a 26 y dryland fertilization trial in Pingliang, Gansu, China, were recorded. Cumulative C inputs from straw and root and manure for fertilizer treatments were estimated. Mean wheat (Triticum aestivum L.) yields for the 18 y ranged from 1.72 t ha–1 for the unfertilized plots (CK) to 4.65 t ha–1 for the plots that received manure (M) annually with inorganic N and P fertilizers (MNP). Corn (Zea mays L.) yields for the 6 y averaged 2.43 and 5.35 t ha–1 in the same treatments. Yields declined with year except in the CK for wheat. Wheat yields for N only declined with time by 117.8 kg ha–1 y–1 that was the highest decrease among all treatments, and that for NP declined by 84.7 kg ha–1 y–1, similar to the declines of 77.4 kg ha–1 y–1 for the treatment receiving straw and N annually and P every second year (SNP). Likewise, the corn yields declined highly for all treatments, and the declined amounts ranged from 108 to 258 kg ha–1 y–1 which was much higher than in wheat. These declined yields were mostly linked to both gradual dry weather and nutrients depletion of the soil. The N only resulted in both P and K deficiency in the soil, and soil N and K negative balances in the NP and MNP were obvious. Soil organic carbon (SOC) in the 0–20 cm soil layer increased with time except in the CK and N treatments, in which SOC remained almost stable. In the MNP and M treatments, 24.7% and 24.0% of the amount of cumulative C input from organic sources remained in the soil as SOC, but 13.7% of the C input from straw and root in the SNP, suggesting manure is more effective in building soil C than straw. Across the 26 y cropping and fertilization, annual soil‐C sequestration rates ranged from 0.014 t C ha–1 y–1 for the CK to 0.372 t C ha–1 y–1 for the MNP. We found a strong linear relationship (R2 = 0.74, p = 0.025) between SOC sequestration and cumulative C input, with C conversion–to–SOC rate of 16.9%, suggesting these dryland soils have not reached an upper limit of C sequestration.
Comparison of different methods for the measurement of ammonia volatilization after urea application in Henan Province, China
Authors: Pacholski Andreas , Cai Gui‐Xin , Fan Xiao‐Hui , Ding Hong , Chen Deli , Nieder Rolf , Roelcke Marco 
Published: June 2008

AbstractAmmonia losses following urea fertilization of maize and winter wheat were determined in field trials carried out at Fengqiu Experimental Station in the North China Plain in 1998 and 1999. Four experiments were carried out using two simplified micrometeorological integrated horizontal flux methods [IHF(L) and IHF(S)], a chamber method (calibrated Dräger‐Tube Method DTM) and the 15N‐balance method using 15N‐labeled urea. The IHF(L) was taken as the reference method. Both IHF methods showed good agreement in one experiment only, while the IHF(S) overestimated as well as underestimated cumulative ammonia losses compared to IHF(L) in the other experiments (deviation ranged from 12.5% to 64% based on cumulative ammonia losses). Regression analysis of the fluxes showed that in particular different sensitivities of the samplers to wind speed accounted for the discrepancies observed. The IHF(L) and the DTM flux curves were very similar in three experiments, while the values obtained with DTM considerably deviated from IHF(L) results in one experiment. A comparison with apparent fertilizer‐N losses determined by the 15N‐labeling approach showed that ammonia volatilization was the major pathway of fertilizer‐N loss in this study.
Use of mid‐infrared spectroscopy in the diffuse‐reflectance mode for the prediction of the composition of organic matter in soil and litter
Authors: Ludwig Bernard , Nitschke Renate , Terhoeven‐Urselmans Thomas , Michel Kerstin , Flessa Heiner 
Published: June 2008

AbstractMid‐infrared spectroscopy (MIRS) is assumed to be superior to near‐infrared spectroscopy (NIRS) for the prediction of soil constituents, but its usefulness is still not sufficiently explored. The objective of this study was to evaluate the ability of MIRS to predict the chemical and biological properties of organic matter in soils and litter. Reflectance spectra of the mid‐infrared region including part of the near‐infrared region (7000–400 cm–1) were recorded for 56 soil and litter samples from agricultural and forest sites. Spectra were used to predict general and biological characteristics of the samples as well as the C composition which was measured by 13C CPMAS‐NMR spectroscopy. A partial least‐square method and cross‐validation were used to develop equations for the different constituents over selected spectra ranges after several mathematical treatments of the spectra. Mid‐infrared spectroscopy predicted well the C : N ratio: the modeling efficiency EF was 0.95, the regression coefficient (a) of a linear regression (measured against predicted values) was 1.0, and the correlation coefficient (r) was 0.98. Satisfactorily (EF ≥ 0.70, 0.8 ≤ a ≤ 1.2, r ≥ 0.80) assessed were the contents of C, N, and lignin, the production of dissolved organic carbon, and the contents of carbonyl C, aromatic C, O‐alkyl C, and alkyl C. However, the N mineralization rate, the microbial biomass and the alkyl–to–aromatic C ratio were predicted less satisfactorily (EF < 0.70). Limiting the sample set to mineral soils did generally not result in improved predictions. The good and satisfactory predictions reported above indicate a marked usefulness of MIRS in the assessment of chemical characteristics of soils and litter, but the accuracies of the MIRS predictions in the diffuse‐reflectance mode were generally not superior to those of NIRS.
Challenges of species distribution modeling belowground
Authors: Schröder Boris 
Published: June 2008

AbstractUnderstanding the relationship between soil biodiversity, habitat, and function is one of the main issues of soil‐ecological research. The description of spatiotemporal distributions of soil organisms at relevant scales and in relation to their activity is a prerequisite to understand and quantify the factors that control soil functions. Species distribution models can help to explain the functional relationships between organisms and their habitat by estimating occurrence probabilities from spatial‐distribution data and environmental predictors for single species or species groups. Here, I present a brief overview of recent developments in species distribution models and illustrate this tool with a case study using a carabid beetle species in a small‐scale highly heterogeneously structured environment. In the light of the peculiarities of soil organisms and habitat, several implications and challenges of species distribution models are discussed referencing some instructive studies on the spatial distribution of soil organisms over a range of spatiotemporal scales. The most important challenges of species distribution models for soil organisms comprise the spatiotemporal heterogeneity of soil habitat on a hierarchy of nested scales; the overwhelming diversity of soil organisms with largely unknown life histories, habitat requirements, and dispersal characteristics; taxonomic and technical limitations regarding sampling and measurements; feedbacks between soil biota and their habitat. There is a clear theoretical and practical basis for considering both environmental and geographic drivers of species distributions in soil studies, and for doing so across multiple scales. This would yield a habitat‐based soil ecology by combining the spatially explicit approach proposed by Ettema and Wardle (2002) with the niche‐based approach of species distribution modeling.
A spatial approach to soil‐ecological experimentation at landscape scale
Authors: Joschko Monika , Oehley Jörg , Gebbers Robin , Wiemer Martina , Timmer Jens , Fox Catherine A. 
Published: June 2008

AbstractThe upscaling of soil‐ecological processes to larger landscape units represents a special challenge to soil ecology. Results from micro‐ or mesocosms cannot easily be transferred to other scales because effects are often scale‐dependent. In this context, field experiments which take into account the heterogeneity of the landscape may be promising. Therefore, we carried out an experiment based on a transect study in the agrolandscape of NE Germany on heterogeneous sandy soil in which the feeding activity of the soil‐organism community was assessed by means of the bait‐lamina test at each of the 101 transect locations. At every 4th position, prior to the measurement the soil biota were stimulated by a treatment consisting of adding easily available C and water to the soil. Our aim was to test whether this kind of spatial approach enables to separate effects induced by treatments from landscape effects. The results showed a highly variable feeding activity along the transect after 4 weeks. Despite this variability, a basic trend could be identified which was related to a landscape factor,i.e., the relief. On upper‐slope positions, the feeding activity tended to be less in comparison to positions down‐slope. At every 4th position of the transect, the stimulating effect of the substrate and water addition could be clearly detected and quantified with spectral and cross‐spectral analysis. It is concluded that effects of treatments in heterogeneous landscapes may be distinguished from site effects when the signal‐to‐noise ratio is high and soil and treatment effects on the variable of interest are sufficiently different from one another. In a heterogeneous landscape with gradients of site properties, a treatment based on the frequency domain and applied in regular intervals can be distinguished with spectral analysis techniques.
Plant‐available nitrogen in the soil: Relationships between pre‐plant and pre‐sidedress nitrate tests for corn production
Authors: Ma Bao Luo , Wu Tian‐Yun 
Published: June 2008

AbstractCorn (Zea mays L.) producers in the rainfed regions sometimes sidedress fertilizer N according to pre‐plant–nitrate test (PPNT) results based on the assumption that there is a linear relationship between pre‐sidedress nitrate test (PSNT) and the PPNT. There has been no report on such relationship in Ontario (Canada) and elsewhere in the nonirrigated corn‐growing regions. A field study was conducted near Ottawa, Canada for 7 y to (1) determine changes in soil available N from pre‐planting to shortly after the sidedress stage (late June) for corn and (2) establish a quantitative relationship between PPNT and PSNT. In each year, soil samples from fields of three to four plot experiments with different cropping histories, soil textures, and management levels, taken at 7 to 10 d intervals, and from on‐farm trials taken at pre‐planting and pre‐sidedress, were extracted with 2 M KCl. The concentrations of NO$ _3^- $‐N were determined colorimetrically. It was found that soil NO$ _3^- $‐N concentration of PSNT was a linear function of PPNT with an average slope of 1.7. However, the slope of the regression equations differed dramatically among cropping sequences, and to a lesser extent, soil textures. The NO$ _3^- $‐N concentration after planting to pre‐sidedress was influenced by air temperature and precipitation during this period of time. Both PPNT and PSNT positively correlated with corn‐grain yield. Our data suggest that cautions must be taken when deciding the rate of fertilizer N for sidedress application to corn based on PPNT test, especially under more humid northern climate conditions.
Total soil heavy‐metal concentrations and mobile fractions after 10 years of biowaste‐compost fertilization
Authors: Erhart Eva , Hartl Wilfried , Putz Berta 
Published: June 2008

AbstractThe accumulation of heavy metals (HMs) in soils is the most often cited potential risk of compost application. As the ecological effects of metals are related to mobile fractions rather than to total concentrations in the soil, we measured the total (aqua regia–extractable) HM concentrations, the readily available water‐soluble and the potentially bioavailable LiCl‐extractable fraction of soil HMs in a field experiment after 10 y with total applications of 95, 175, and 255 t ha–1 biowaste compost (fresh matter). Total soil concentrations of Cd, Cr, Cu, Ni, and Pb in the compost treatments were not significantly higher than in the unfertilized control. Total Zn concentrations increased in the treatment with the highest application rate, as expected from the calculation of the Zn load in the composts. In the mobile fractions, as measured in soil saturation extract and LiCl extract, Cd and Pb were not detectable. Concentrations of Cr, Ni, and Zn were in the range published for unpolluted soils in other studies and did not show any differences according to treatment. Easily exchangeable Cu (in LiCl extract) was increased with compost fertilization, most probably due to complexation with low‐molecular organic complexants. Except for Cd and Zn, the results of the mobile HM fractions in the soil were in good agreement with plant HM concentrations. In conclusion, fertilization with high‐quality biowaste compost at such rates and after 10 y of application gives no cause for concern with regard to both total HM concentrations and available HM fractions.
Potassium efficiency of safflower (Carthamus tinctorius L.) and sunflower (Helianthus annuus L.)
Authors: Gerendás Jóska , Abbadi Jehad , Sattelmacher Burkhard 
Published: June 2008

AbstractThe oil crop safflower may have a certain production potential under low‐input conditions (organic farming, developing countries), where the putatively low nutrient requirement is highly welcomed. However, current knowledge regarding the nutrient use efficiency of safflower as compared to similar oil crops is limited. It was thus the aim of this study to determine the potassium (K) use efficiency of safflower (Carthamus tinctorius L.) as compared to sunflower (Helianthus annuus L.). Safflower and sunflower were cultivated with increasing K supply in a mixture of equal volumes of sand, nutrient‐poor limed soil, and perlite in 5 L Mitscherlich pots. Both species responded strongly to increasing K supply with respect to growth and yield. Safflower out‐yielded sunflower at low K supply, while at high K level, the opposite was observed. Both species accumulated similar amounts of K in shoots at low K supply. Only at extremely low K supply, safflower took up more K than sunflower. However, achene yield of sunflower exceeded that of safflower at optimal and high K supply. Safflower utilized absorbed K more efficiently than sunflower to produce achene yield at suboptimal K supply in terms of both efficiency ratio and utilization index. The efficiency of a crop to use supplied or accumulated K for dry‐matter and achene production was interpreted in terms of Michaelis‐Menten kinetics, specifically addressing the shape of the yield response curve. Indeed, the efficiency of safflower to use K for growth and yield, analogue to a low Km in enzyme kinetics, was higher than in sunflower, while the K supply or K accumulation required to initiate yield formation in safflower was significantly lower. Similarly, safflower had a lower external K requirement for achene yield than sunflower at low and optimal K supplies. It can be concluded that safflower represents a low‐input crop and outperforms sunflower on soils low in available K. The data analysis also reveals that using just one efficiency indicator is usually not sufficient to adequately describe the K efficiency of the crop under consideration.
Influence of nitrogen and weed management on the productivity of upland rice
Authors: Singh Chandra Vir , Ghosh Bidhan Chandra , Mittra Bishwa Nath , Singh Rama Kant 
Published: June 2008

AbstractNitrogen and weeds are two important factors that influence the productivity of rainfed upland rice (Oryza sativa L.) in tropical Asia. A low recovery of applied fertilizer N in rainfed uplands is generally associated with high nitrate leaching losses and weed interferences. Field experiments were conducted during the wet seasons of 2002 and 2003 at the research farm of Central Rainfed Upland Rice Research Station, Hazaribag, Jharkhand, India, to determine the response of upland rice to nitrogen applied at 60 kg N ha–1 as different forms of urea (single pre‐plant application of controlled‐release urea, single pre‐plant application of urea supergranules, and split application of prilled urea with or without basal N) against no N application under three weed‐control regimes (unweeded, pre‐emergence application of butachlor at 1.5 kg a.i. ha–1 supplemented with one single hand weeding or two hand weedings). The response of rice to applied N varied greatly among the three weed‐control regimes. Across the different N treatments, the application of 60 kg N ha–1 resulted in a grain‐yield increase above the unfertilized control of only 0.24 Mg ha–1 in unweeded treatments, whereas yields increased by 1.07 Mg ha–1 when butachlor application was supplemented with a single hand weeding and by 1.28 Mg ha–1 with two hand weedings. Among the weed‐control measures, hand weeding twice produced highest grain yield in both years. The comparison of different forms of urea showed that a single pre‐plant application of controlled‐release urea resulted in average grain yields of 1.57 and 1.87 Mg ha–1 compared to 1.32 and 1.30 Mg ha–1 in the case of the recommended practice of split‐applied prilled urea in the years 2002 and 2003, respectively. The highest agronomic N use efficiency of 15–20 kg grain per kg N applied and the highest apparent N recovery of 39%–45% were attained with controlled‐release urea, suggesting that this N form is particularly beneficial for upland‐rice cultivation under variable rainfall conditions, provided weeds are controlled.
Nanofabricated periodic arrays of silver elliptical discs as SERS substrates
Authors: Oran Jenny M. , Hinde Robert J. , Abu Hatab Nahla , Retterer Scott T. , Sepaniak Michael J. 
Published: June 2008

AbstractSignal enhancement observed in surface‐enhanced Raman spectroscopy (SERS) is attributable to the presence of noble‐metal nanostructures on substrate surfaces. The rational development of SERS‐active substrates depends critically on the homogeneity and intensity of surface plasmon resonances, properties that are strongly dependent on both the morphology and dielectric properties of the metals and composite materials making up the SERS substrates. Enhancement can be controlled by the shape, size, and spacing of metallic nanoparticles. Previous studies in our group have shown that arrays of elliptical nanodiscs have promising geometries for this purpose. Using electron beam lithography (EBL), we fabricate close‐packed arrays of these discs with lateral dimensions ranging from 300:50 to 300:300 nm (long axis : short axis). The arrays are composed of a negative photoresist that, once the lithography process is complete, are coated with a noble metal through physical vapor deposition (PVD). In this work, optimum thickness and deposition rate of noble metal are determined for these substrates. The lithographically produced nanopatterns are studied by Raman spectroscopy to examine the effect of altering the elliptical aspect ratio on SERS activity, while scanning electron microscopy (SEM) is used to examine pattern surfaces post lithographic development and post noble‐metal deposition. Atomic force microscopy (AFM) is used to inspect the roughness of substrate surfaces. Reproducibility between different arrays of the same pattern ranges from 12 to 28%. Homogeneity of our uniform‐morphology EBL/PVD‐fabricated substrates is examined and compared to our random‐morphology polymer nanocomposite substrates. Using rhodamine 6G as an analyte, an increase in SERS signal is noted as the aspect ratio of ellipses goes from 6:1 to 6:6. Our experimental data, in terms of trends in SERS activity, correlate with trends in field enhancements calculated using a simple electrostatic model and with the magnitude of the broad red‐shifted spectral continuum observed for the substrates. Copyright © 2008 John Wiley & Sons, Ltd.