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1.
Application of earthworm in soil re-cultivation and re-creation in post-industrial ecosystems make a big challenge for temporal applied zoology. The sediments of the Krakow Soda Works “Solvay” have undergone land reclamation in different ways: older sediments traps were left without any re-cultivation practices; meanwhile the newest ones were reclaimed using standard method (new soil cover planted with combination of grass and leguminous plants). The effect of different treatments on community and population structure of earthworm was estimated during consecutive years 1999–2000. Six localities differing in time of establishment, reclamation processes, vegetation type and soil properties were chosen. Nine species were recorded, among which Aporrectodea caliginosa occurred in all localities, being also the most abundant. Two other species, Lumbricus rubellus and Dendrobaena octaedra, which are epigeic species, become most important in forest assemblages and were characteristic for communities of older succession processes. Abundance of adult forms as well as total biomass were significantly affected by soil depth (r = 0.75, P < 0.05, r = 0.917, P < 0.001, respectively). Species richness however was connected with higher amount of macroelements and average plant height. Shannon diversity index and its evenness negatively correlated only with forestation (r = –0.67, P < 0.05, r = –0.68, P < 0.05, respectively). Niche overlap (α Pianka) for all analysed species extracted two groups differing in environmental requirements. First contained epigeic earthworms, closely related to plant succession (PCA results), the other one grouped endogeic and anecique species correlated significantly with soil depth and plant density. Community structure of earthworms do not reflects succession changes in post-industrial habitats, but is strongly affected by microhabitat factors in local scale (mainly soil depth and plant density). 相似文献
2.
《Soil & Tillage Research》2007,92(1-2):22-29
Sustainable agricultural use of cultivated desert soils has become a concern in Hexi Corridor in Gansu Province of China, because loss of topsoil in dust storms has been recently intensified. We chose four desert sites to investigate the effects of cultivation (cropping) on (i) soil organic C and its size fractions and (ii) soil aggregate stability (as a measure of soil erodibility). These parameters are of vital importance for evaluating the sustainability of agricultural practices.Total organic C as well as organic C fractions in soil (coarse organic C, 0.1–2 mm; young organic C, 0.05–0.1 mm; stable organic C, <0.05 mm) generally increased with the duration of the cultivation period from 0 (virgin soil, non-cultivated) to more than 30 years (p < 0.05). Compared to total organic C in virgin soils (2.3–3.5 g kg−1 soil), significantly greater values were found after 10 to >20 years of cultivation (6.2–7.1 g kg−1 soil). The increase in organic C in desert soils following prolonged cultivation was mainly the consequence of an increase in the coarse organic C. The increase in total organic C in soil was also dependent on clay content [total organic C = 0.96 + 0.249 clay content (%) + 0.05 cultivation year, R2 = 0.48, n = 27, p < 0.001]. This indicates that clay protected soil organic C from mineralization, and also contributed to the increase in soil organic C as time of cultivation increased.There was a significant positive correlation between aggregate stability and total organic C across all field sites. The water stability of aggregates was low (with water-stable aggregate percentage ∼4% of dry-sieved aggregates of size 1–5 mm). There was no consistent pattern of increase in the soil aggregate stability with time of cultivation at different locations, suggesting that desert soils might remain prone to wind erosion even after 50 years of cultivation. Alternative management options, such as retaining harvested crop residues on soil surface and excluding or minimizing tillage, may permit sustainable agricultural use of desert soils. 相似文献
3.
Land use changes in the Amazon region strongly impact soil macroinvertebrate communities, which are recognized as major drivers of soil functions (Lavelle et al., 2006). To explore these relations, we tested the hypotheses that (i) soil macrofauna communities respond to landscape changes and (ii) soil macrofauna and ecosystem services are linked. We conducted a survey of macrofauna communities and indicators of ecosystem services at 270 sites in southern Colombia (department of Caqueta) and northern Brazil (state of Pará), two areas of the Amazon where family agriculture dominates. Sites represented a variety of land use types: forests, fallows, annual or perennial crops, and pastures. At each site we assessed soil macroinvertebrate density (18 taxonomic units) and the following ecosystem service indicators: soil and aboveground biomass carbon stock; water infiltration rate; aeration, drainage and water storage capacities based on pore-size distribution; soil chemical fertility; and soil aggregation. Significant covariation was observed between macrofauna communities and landscape metric data (co-inertia analysis: RV = 0.30, p < 0.01, Monte Carlo test) and between macrofauna communities and ecosystem service indicators (co-inertia analysis: RV = 0.35, p < 0.01, Monte Carlo test). Points located in pastures within 100 m of forest had greater macrofauna density and diversity than those located in pastures with no forest within 100 m (Wilcoxon rank sum test, p < 0.01). Total macroinvertebrate density was significantly correlated with macroporosity (r2 = 0.42, p < 0.01), as was the density of specific taxonomic groups: Chilopoda (r2 = 0.43, p < 0.01), Isoptera (r2 = 0.30, p < 0.01), Diplopoda (r2 = 0.31, p < 0.01), and Formicidae (r2 = 0.13, p < 0.01). Total macroinvertebrate density was also significantly correlated with available soil water (r2 = 0.38, p < 0.01) as well as other soil-service indicators (but with r2 < 0.10). Results demonstrate that landscape dynamics and composition affect soil macrofauna communities, and that soil macrofauna density is significantly correlated with soil services in deforested Amazonia, indicating that soil macrofauna have an engineering and/or indicator function. 相似文献
4.
In the state of Tabasco, South-eastern, Mexico, land-use changes such as the conversion of natural into agricultural systems, modify soil quality and the abundance of soil macrofauna, including earthworms. The aim of this study was to characterize by near-infrared spectroscopy (NIRS) the earthworms’ fingerprint in soil, in six sites including natural and agricultural ecosystems with low and high earthworm biomass and low and high earthworm diversity, in order to identify specific wavelengths that discriminate the presence/abundance of earthworm species and functional groups. The spectral region of 1860–1870 nm was significantly correlated with total earthworm density, particularly at one of the sites (Cedar polyculture; r = 0.8, p < 0.05). Earthworm biomass had a specific NIRS wavelength according to the earthworm species and feeding category: 1820 and1860–1870 nm wavelengths were significantly correlated with Polypheretima elongata (r2 = 0.7, p < 0.05; mesohumic species) biomass and 2090 nm for biomass of all Lavellodrilus species (polyhumics). Two species had a much wider spectral range: L. bonampakensis and Dichogaster saliens (an epigeic worm; 1690–2300 nm, r2 = 0.7, p < 0.05). Biomasses of Periscolex brachysistis and Diplotrema murchiei were not significantly correlated with any near infrared wavelength spectra analyzed. Combining a maximum of 4 species per wavelength, mesohumic earthworms had a wider wavelength spectrum than polyhumics. Therefore, earthworm species diversity, biomass and abundance are associated with soil quality (as measured by NIR spectra) and this relationship varies with species and ecological category. Sites with lower and higher earthworm diversity have lower and higher soil organic matter quality, respectively, as observed by the wider or narrower spectral range with which earthworm biomasses are correlated. 相似文献
5.
Soil N2O emissions can affect global environments because N2O is a potent greenhouse gas and ozone depletion substance. In the context of global warming, there is increasing concern over the emissions of N2O from turfgrass systems. It is possible that management practices could be tailored to reduce emissions, but this would require a better understanding of factors controlling N2O production. In the present study we evaluated the spatial variability of soil N2O production and its correlation with soil physical, chemical and microbial properties. The impacts of grass clipping addition on soil N2O production were also examined. Soil samples were collected from a chronosequence of three golf courses (10, 30, and 100-year-old) and incubated for 60 days at either 60% or 90% water filled-pore space (WFPS) with or without the addition of grass clippings or wheat straw. Both soil N2O flux and soil inorganic N were measured periodically throughout the incubation. For unamended soils, cumulative soil N2O production during the incubation ranged from 75 to 972 ng N g−1 soil at 60% WFPS and from 76 to 8842 ng N g−1 soil at 90% WFPS. Among all the soil physical, chemical and microbial properties examined, soil N2O production showed the largest spatial variability with the coefficient of variation ~110% and 207% for 60% and 90% WFPS, respectively. At 60% WFPS, soil N2O production was positively correlated with soil clay fraction (Pearson's r = 0.91, P < 0.01) and soil NH4+–N (Pearson's r = 0.82, P < 0.01). At 90% WFPS, however, soil N2O production appeared to be positively related to total soil C and N, but negatively related to soil pH. Addition of grass clippings and wheat straw did not consistently affect soil N2O production across moisture treatments. Soil N2O production at 60% WFPS was enhanced by the addition of grass clippings and unaffected by wheat straw (P < 0.05). In contrast, soil N2O production at 90% WFPS was inhibited by the addition of wheat straw and little influenced by glass clippings (P < 0.05), except for soil samples with >2.5% organic C. Net N mineralization in soil samples with >2.5% organic C was similar between the two moisture regimes, suggesting that O2 availability was greater than expected from 90% WFPS. Nonetheless, small and moderate changes in the percentage of clay fraction, soil organic matter content, and soil pH were found to be associated with large variations in soil N2O production. Our study suggested that managing soil acidity via liming could substantially control soil N2O production in turfgrass systems. 相似文献
6.
《Applied soil ecology》2006,33(3):284-292
We examined the response of the temperature coefficient (Q10) for soil respiration to changes in soil temperature and soil moisture through a laboratory incubation experiment. Two types of soils differing in vegetation and moisture status were collected and incubated under two temperatures (10 and 30 °C) and two soil moisture regimes (35 and 75% of water holding capacity, WHC) for 5 weeks. Before and after the incubation experiment, the temperature coefficient of soil respiration was measured using soda-lime method by changing temperature in a water bath. For both soils, the mean Q10 values of the respiration rate were 2.0 in the 30 °C and 2.3 in the 10 °C soil treatments. Higher temperature with lower soil moisture treatment significantly decreased the Q10 value, whereas lower temperature with higher soil moisture treatment significantly enhanced the Q10 value (ANOVA, p < 0.05). These results indicate that soils became less sensitive to temperature when incubated under higher temperature with higher moisture conditions, and more sensitive in lower temperature with higher moisture conditions.There was a significant correlation (r2 = 0.67, p < 0.05) between water-soluble carbon (WSC) and soil respiration rate. However, the correlation between soil respiration rate and microbial biomass carbon (MBC) was weak (r2 = 0.27, p > 0.05). Although incubation temperature and moisture accounted for 40 and 29% (as r2 × 100%), respectively, of variations in Q10, soil water-soluble carbon content alone could have explained 79% of the variation, indicating that the availability of respiratory substrate, rather than the pool of soil microorganisms, played a crucial role in the response of the temperature coefficient to environmental factors. These results suggest that biotic factors should also be taken into consideration when using the Q10 function to predict the response of soil respiration to global warming. 相似文献
7.
《Pedobiologia》2014,57(4-6):277-284
Assimilating atmospheric carbon (C) into terrestrial ecosystems is recognized as a primary measure to mitigate global warming. Ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) is the dominant enzyme by which terrestrial autotrophic bacteria and plants fix CO2. To investigate the possibility of using RubisCO activity as an indicator of microbial CO2 fixation potential, a valid and efficient method for extracting soil proteins is needed. We examined three methods commonly used for total soil protein extraction. A simple sonication method for extracting soil protein was more efficient than bead beating or freeze–thaw methods. Total soil protein, RubisCO activity, and microbial fixation of CO2 in different agricultural soils were quantified in an incubation experiment using 14C-CO2 as a tracer. The soil samples showed significant differences in protein content and RubisCO activity, defined as nmol CO2 fixed g−1 soil min−1. RubisCO activities ranged from 10.68 to 68.07 nmol CO2 kg−1 soil min−1, which were closely related to the abundance of cbbL genes (r = 0.900, P = 0.0140) and the rates of microbial CO2 assimilation (r = 0.949, P = 0.0038). This suggests that RubisCO activity can be used as an indicator of soil microbial assimilation of atmospheric CO2. 相似文献
8.
Documented approaches for measuring soil microbial activities and their controlling factors under field conditions are needed to advance understanding of soil microbial processes for numerous applications. We manipulated field plots with carbon (C) and nitrogen (N) additions to test the capability of a respiratory assay to: (1) measure respiration of endogenous soil C in comparison to field-measured CO2 fluxes; (2) determine substrate-induced respiratory (SIR) activities that are consistent with substrate availability in the field; and, (3) report N availability in the field based on assay responses with and without added N. The respiratory assay utilizes a microplate containing an oxygen-sensitive fluorescent ruthenium dye. Respiratory activities measured with this approach have previously been shown to occur within short (6–8 h) incubation periods using low substrate concentrations that minimize enrichment during the assay. Field treatments were conducted in a randomized full-factorial design with C substrate (casamino acids, glucose, or none) and inorganic N (±) as the treatment factors. With one exception, we found that respiration of endogenous soil C in the assay responded to the field treatments in a similar manner to CO2 fluxes measured in the field. Patterns of SIR with low concentrations of added amino acid or carbohydrate substrate (200 μg C g−1 soil) were consistent with field treatments. The ratio (Nratio) of carbohydrate respiration with added N (25 μg N g−1 soil) to the same without N in the assay was significantly (P < 0.05) decreased by field N amendment. The carbohydrate Nratio exhibited a logarithmic relationship (r = 0.64, P < 0.05) with extractable inorganic soil nitrate and ammonium concentrations. These data significantly extend and support the capability of this oxygen-based respiratory assay to evaluate in situ soil activities and examine factors that limit these activities. 相似文献
9.
The near infrared reflectance spectroscopy (NIRS) method was used in the present study to compare earthworm-made soil aggregates to aggregates found in the surrounding bulk soil. After initially assessing the daily cast production of Metaphire posthuma, boxes with soil incubated with M. posthuma and control soils were subjected to wetting in order to reorganize the soil structure. After two months of incubation, soil aggregates produced by earthworms (casts and burrows), soil aggregates that were appeared to be unaffected by earthworms (bulk soil without visible trace of earthworm bioturbation from the earthworm treatment) and soil aggregates that were entirely unaffected by earthworms (control – no earthworm – treatment) were sampled and their chemical signatures analyzed by NIRS. The production of below-ground and surface casts reached 14.9 g soil g worm?1 d?1 and 1.4 g soil g worm?1 d?1, respectively. Soil aggregates from the control soils had a significantly different NIRS signature from those sampled from boxes with earthworms. However, within the earthworm incubation boxes the NIRS signature was similar between cast and burrow aggregates and soil aggregates from the surrounding bulk soil. We conclude that the high cast production by M. posthuma and the regular reorganization of the soil structure by water flow in and through the soil lead to a relatively homogenous soil structure. Given these results, we question the relevance of considering the bulk soil that has no visible activity of earthworm activity as a control to determine the effect of earthworms on soil functioning. 相似文献
10.
《European Journal of Soil Biology》2008,44(4):437-442
Long-term field experiments are expected to provide important information regarding soil properties affected by conservation management practices. Several studies have shown that soil enzyme activities are sensitive in discriminating among soil management effects. In this study we evaluated the long-term effect of direct drilling (DD) under a crop rotation system (cereals–sunflower–legumes), on the stratification of soil organic matter content and on biochemical properties in a dryland in southwest Spain. The results were compared to those obtained under conventional tillage (CT). Soil biochemical status was evaluated by measuring the enzymatic activities (dehydrogenase, β-glucosidase, alkaline phosphatase and arylsulphatase) during the flowering period of a pea crop. Soil samples were collected in May 2007 at three depths (0–5, 5–10 and 10–20 cm).Total organic carbon (TOC) contents and values of soil enzyme activities were higher in soils subjected to DD than to CT, specifically at 0–5 cm depth. Although a slight decrease of TOC and enzymatic activities with increasing soil depth was observed, no significant differences were found among different depths of the same treatment. This could be related to the high clay content of the soil, a Vertisol. Enzyme activities values showed high correlation coefficients (from r = 0.799 to r = 0.870, p < 0.01) with TOC. Values of activity of the different enzymes were also correlated (p < 0.01).Values of stratification ratios did not show significant differences between tillage practices. The high clay content of the soil is responsible for this lack of differences because of the protection by clay mineral of TOC and soil enzymes activities.Long-term soil conservation management by direct drilling in a dryland farming system improved the quality of a clay soil, especially at the surface, by enhancing its organic matter content and its biological status. 相似文献
11.
Building soil structure in agroecosystems is important because it governs soil functions such as air and water movement, soil C stabilization, nutrient availability, and root system development. This study examined, under laboratory conditions, effects of organic amendments comprised of differing proportions of labile and semi-labile C on microbial community structure and macroaggregate formation in three variously textured soils where native structure was destroyed. Three amendment treatments were imposed (in order of increasing C lability): vegetable compost, dairy manure, hairy vetch (Vicia villosa Roth). Formation of water stable macroaggregates and changes in microbial community structure were evaluated over 82 days. Regardless of soil type, formation of large macroaggregates (LMA, >2000 μm diameter) was highest in soils amended with vetch, followed by manure, non-amended control, and compost. Vetch and manure had greater microbially available C and caused an increase in fungal biomarkers in all soils. Regression analysis indicated that LMA formation was most strongly related to the relative abundance of the fungal fatty acid methyl ester (FAME) 18:2ω6c (r = 0.55, p < 0.001), fungal ergosterol (r = 0.58, p < 0.001), and microbial biomass (r = 0.57, p < 0.001). Non-metric multidimensional scaling (NMS) ordination of FAME profiles revealed that vetch and manure drove shifts toward fungal-dominated soil microbial communities and greater LMA formation in these soils. This study demonstrated that, due to their greater amounts of microbially available C, vetch or manure inputs can be used to promote fungal proliferation in order to maintain or improve soil structure. 相似文献
12.
R. Zornoza C. Guerrero J. Mataix-Solera K.M. Scow V. Arcenegui J. Mataix-Beneyto 《Soil biology & biochemistry》2008,40(7):1923-1930
The potential of near infrared (NIR) reflectance spectroscopy to predict various physical, chemical and biochemical properties in Mediterranean soils from SE Spain was evaluated. Soil samples (n = 393) were obtained by sampling 13 locations during three years (2003–2005 period). These samples had a wide range of soil characteristics due to variations in land use, vegetation cover and specific climatic conditions. Biochemical properties also included microbial biomarkers based on phospholipid fatty acids (PLFA). Partial least squares (PLS) regression with cross validation was used to establish relationships between the NIR spectra and the reference data from physical, chemical and biochemical analyses. Based on the values of coefficient of determination (r2) and the ratio of standard deviation of validation set to root mean square error of cross validation (RPD), predicted results were evaluated as excellent (r2 > 0.90 and RPD > 3) for soil organic carbon, Kjeldahl nitrogen, soil moisture, cation exchange capacity, microbial biomass carbon, basal soil respiration, acid phosphatase activity, β-glucosidase activity and PLFA biomarkers for total bacteria, Gram-positive bacteria, actinomycetes, vesicular-arbuscular mycorrhizal fungi and total PLFA biomass. Good predictions (0.81 < r2 < 0.90 and 2.5 < RPD < 3) were obtained for exchangeable calcium and magnesium, water soluble carbon, water holding capacity and urease activity. Resultant models for protozoa and fungi were not accurate enough to satisfactorily estimate these variables, only permitting approximate predictions (0.66 < r2 < 0.80 and 2.0 < RPD < 2.5). Electrical conductivity, pH, exchangeable phosphorus and sodium, metabolic quotient and Gram-negative bacteria were poorly predicted (r2 < 0.66 and RPD < 2). Thus, the results obtained in this study reflect that NIR reflectance spectroscopy could be used as a rapid, inexpensive and non-destructive technique to predict some physical, chemical and biochemical soil properties for Mediterranean soils, including variables related to the composition of the soil microbial community composition. 相似文献
13.
《Soil biology & biochemistry》2001,33(7-8):1103-1111
Biologically active fractions of soil organic matter are important in understanding decomposition potential of organic materials, nutrient cycling dynamics, and biophysical manipulation of soil structure. We evaluated the quantitative relationships among potential C and net N mineralization, soil microbial biomass C (SMBC), and soil organic C (SOC) under four contrasting climatic conditions. Mean SOC values were 28±11 mg g−1 (n=24) in a frigid–dry region (Alberta/British Columbia), 25±5 mg g−1 (n=12) in a frigid–wet region (Maine), 11±4 mg g−1 (n=117) in a thermic–dry region (Texas), and 12±5 mg g−1 (n=131) in a thermic–wet region (Georgia). Higher mean annual temperature resulted in consistently greater basal soil respiration (1.7 vs 0.8 mg CO2–C g−1 SOC d−1 in the thermic compared with the frigid regions, P<0.001), greater net N mineralization (2.8 vs 1.3 mg inorganic N g−1 SOC 24 d−1, P<0.001), and greater SMBC (53 vs 21 mg SMBC g−1 SOC, P<0.001). Specific respiratory activity of SMBC was, however, consistently lower in the thermic than in the frigid regions (29 vs 34 mg CO2–C g−1 SMBC d−1, P<0.01). Higher mean annual precipitation resulted in consistently lower basal soil respiration (1.1 vs 1.3 mg CO2–C g−1 SOC d−1 in the wet compared with the dry regions, P<0.01) and lower SMBC (31 vs 43 mg SMBC g−1 SOC, P<0.001), but had inconsistent effects on net N mineralization that depended upon temperature regime. Specific respiratory activity of SMBC was consistently greater in the wet than the dry regions (≈33 vs 29 mg CO2–C g−1 SMBC d−1, P<0.01). Although the thermic regions were not able to retain as high a level of SOC as the frigid regions, due likely to high annual decomposition rates, biologically active soil fractions were as high per mass of soil and even 2–3-times greater per unit of SOC in the thermic compared with the frigid regions. These results suggest that macroclimate has a large impact on the portion of soil organic matter that is potentially active, but a relatively small impact on the specific respiratory activity of SMBC. 相似文献
14.
《European Journal of Soil Biology》2008,44(4):408-418
Nitrogen mineralization and nitrification in the soil of sub-alpine ruderal community of Mount Uludağ, Bursa, Turkey was measured for 1 year, under field conditions with Verbascum olympicum and Rumex olympicus being the dominant pioneer species under dry and wet sites, respectively. Seasonal fluctuations were observed in N mineralization and nitrification. The net N mineralization and nitrification were high in early summer and winter, due to high moisture. The annual net N mineralization rate (for the 0–15 cm soil layer) was higher under R. olympicus (188 kg N ha−1 yr−1) than under V. olympicum (96 kg N ha−1 yr−1). A significant positive correlation between net N mineralization and soil organic C (r2 = 0.166), total N (r2 = 0.141) and water content (r2 = 0.211) was found. Our results indicate that N mineralization rate is high in soils of ruderal communities on disturbed sites and varies with dominant species and, a difference in net N mineralization rate can be attributed to organic C, total N and moisture content of soils. 相似文献
15.
《Applied soil ecology》2007,35(3):622-634
Rocky Mountain National Park (RMNP), Colorado, USA, contains a diversity of plant species. However, many exotic plant species have become established, potentially impacting the structure and function of native plant communities. Our goal was to quantify patterns of exotic plant species in relation to native plant species, soil characteristics, and other abiotic factors that may indicate or predict their establishment and success. Our research approach for field data collection was based on a field plot design called the pixel nested plot. The pixel nested plot provides a link to multi-phase and multi-scale spatial modeling-mapping techniques that can be used to estimate total species richness and patterns of plant diversity at finer landscape scales. Within the eastern region of RMNP, in an area of approximately 35,000 ha, we established a total of 60 pixel nested plots in 9 vegetation types. We used canonical correspondence analysis (CCA) and multiple linear regressions to quantify relationships between soil characteristics and native and exotic plant species richness and cover. We also used linear correlation, spatial autocorrelation and cross correlation statistics to test for the spatial patterns of variables of interest. CCA showed that exotic species were significantly (P < 0.05) associated with photosynthetically active radiation (r = 0.55), soil nitrogen (r = 0.58) and bare ground (r = −0.66). Pearson's correlation statistic showed significant linear relationships between exotic species, organic carbon, soil nitrogen, and bare ground. While spatial autocorrelations indicated that our 60 pixel nested plots were spatially independent, the cross correlation statistics indicated that exotic plant species were spatially associated with bare ground, in general, exotic plant species were most abundant in areas of high native species richness. This indicates that resource managers should focus on the protection of relatively rare native rich sites with little canopy cover, and fertile soils. Using the pixel nested plot approach for data collection can facilitate the ecological monitoring of these vulnerable areas at the landscape scale in a time- and cost-effective manner. 相似文献
16.
《European Journal of Soil Biology》2008,44(1):84-91
Soil samples taken from a sewage irrigation area, a partial sewage irrigation area and a ground water irrigation area (control area) were studied with the methods of Biolog and FAME. It was found that the microbial utilization of carbon sources in sewage irrigation areas was much higher than that of control area (P < 0.05). With the increasing of the amount of sewage irrigation, microbial functional diversity slightly increased by the Biolog analysis; however, the amount of epiphyte decreased by the FAME analysis. The results also showed that the Cr, Zn contents were positively correlated with the values of AWCD and the microbial diversity, while Hg content showed negative correlation with the microbial parameters (AWCD of 72 h and Shannon index). Our studies suggested that sewage irrigation resulted in an obvious increase of heavy metals content in soil (P < 0.05), although the maximum heavy metals concentrations were much lower than the current standard of China. Other soil basic characteristics such as cation exchange capacity (CEC), total nitrogen (Nt) and organic matter in sewage irrigation areas obviously increased (P < 0.05). Therefore, it is demonstrated that long-term sewage irrigation had influenced soil microorganisms and soil quality in the studied soils. As a result, it is important to monitor the changes in agricultural soils. Furthermore, our results also confirmed that the methods of Biolog and FAME are effective tools for the assessment of soil microbial structure/function and soil health. 相似文献
17.
Denise C. Lambkin Kerry H. Gwilliam Caroline Layton Matt G. Canti Trevor G. Piearce Mark E. Hodson 《Pedobiologia》2011
Earthworms secrete granules of calcium carbonate. These are potentially important in soil biogeochemical cycles and are routinely recorded in archaeological studies of Quaternary soils. Production rates of calcium carbonate granules by the earthworm Lumbricus terrestris L. were determined over 27 days in a range of soils with differing chemical properties (pH, organic matter content, water holding capacity, bulk composition, cation exchange capacity and exchangeable cations). Production rate varied between soils, lay in the range (0–4.3 mg) earthworm?1 d?1 with an average rate of (0.8 mg) earthworm?1 d?1 and was significantly correlated (r = 0.68, P ≤ 0.01) with soil pH. In a second experiment lasting 315 days earthworms repeatedly (over periods of 39–57 days) produced comparable masses of granules. Converting individual earthworm granule production rates into fluxes expressed on a per hectare of land per year basis depends heavily on estimates of earthworm numbers. Using values of 10–20 L. terrestris m?2 suggests a rate of . Data obtained from flow-through dissolution experiments suggest that at near neutral pH, granule geometric surface area-normalised dissolution rates are similar to those for other biogenic and inorganic calcites. Fits of the data to the dissolution relationship r = k(1 ? Ω)n where r = dissolution rate, k = a rate constant, Ω = relative saturation and n = the reaction order gave values of k = 1.72 × 10?10 mol cm?2 s?1 and n = 1.8 for the geometric surface area-normalised rates and k = 3.51 × 10?13 mol cm?2 s?1 and n = 1.8 for the BET surface area-normalised rates. In 196 day leaching column experiments trends in granule dissolution rate referenced to soil chemistry corresponded to predictions made by the SLIM model for dissolution of limestone in soil. If soil solution approaches saturation with respect to calcium carbonate, granule dissolution will slow or even stop and granules be preserved indefinitely. Granules have the potential to be a small but significant component of the biogeochemical cycling of C and Ca in soil. 相似文献
18.
Earthworms are key regulators of soil structure and soil organic matter (SOM) dynamics in many agroecosystems. They are greatly impacted by agricultural management, yet little is known about how these factors interact to control SOM dynamics. This study sought to explore linkages between agricultural management, earthworms and aggregate associated SOM dynamics through a survey of tomato (Solanum lycopersicum L.) cropping systems in northern California. Earthworms and soil samples were collected between February and April of 2005 from 16 fields under one of three types of residue management: (1) tomato mulch – no postharvest tillage and tomato residues left on the soil surface, (2) cover crop – tomato residues tilled in and leguminous cover crop planted, and (3) bare fallow – tomato residues tilled in and soil surface left exposed throughout the winter. Earthworms were collected via hand-sorting and identified to species, while soils were wet sieved to yield four aggregate size classes: large macroaggregates (>2000 μm), small macroaggregates (250–2000 μm), microaggregates (53–250 μm) and the silt and clay fraction (<53 μm). The combined large and small macroaggregate fraction was then fractionated into coarse particulate organic matter (cPOM; 250 μm), microaggregates within macroaggregates (mM; 53–250 μm) and macroaggregate occluded silt and clay (Msc; <53 μm). The earthworms identified in this survey were composed entirely of exotic species and were dominated by Aporrectodea caliginosa. Earthworm abundance was related to residue management, with the tomato mulch systems averaging 4.5 times greater fresh earthworm biomass than bare fallow (P = 0.024). Aggregate stability and total soil C and N also appeared to be influenced by residue management, such that the tomato mulch system displayed significantly greater mean weight diameters than the bare fallow system (P = 0.049), as well as more than 50% greater total soil C and N (P = 0.049 and P = 0.036; respectively). Earthworm biomass was also found to be positively correlated with total soil C (P = 0.009, R2 = 0.39) and N (P = 0.010, R2 = 0.039) as well as the proportion of macroaggregate C in the cPOM fraction (P = 0.028, R2 = 0.30). Our findings suggest that residue handling and the associated management practices (e.g., tillage, organic vs. conventional agriculture) are important for both earthworm populations and SOM storage. Although earthworms are known to influence SOM in many ways, other factors appear to play a more prominent role in governing aggregate associated SOM dynamics. 相似文献
19.
Noel P. Gurwick Peter M. Groffman Joseph B. Yavitt Arthur J. Gold Gary Blazejewski Mark Stolt 《Soil biology & biochemistry》2008,40(1):85-96
Buried horizons and lenses in riparian soil profiles harbor large amounts of carbon relative to the surrounding soil horizons. Because these buried soil horizons, as well as deep surface horizons, frequently lie beneath the water table, their impact on nitrogen transport across the terrestrial–aquatic interface depends upon their frequency and spatial distribution, and upon the lability of associated organic matter. We collected samples of 51 soil horizons from 14 riparian zones Rhode Island, USA, where soil profiles are characterized by glacial outwash and alluvial deposits. These soil samples came from as deep as 2 m and ranged in carbon content from <1% to 44% in a buried O horizon 54–74 cm deep. We used these samples to: (1) determine the extent to which carbon in buried horizons, and deep surface horizons, is potentially microbially available; (2) identify spatial patterns of carbon mineralization associated with surface and buried horizons; and (3) evaluate likely relationships between soil horizon types, chemical characteristics and carbon mineralization. Carbon mineralization rates associated with buried horizons during anaerobic incubations ranged from 0.0001 to 0.0175 μmol C kg soil?1 s?1 and correlated positively with microbial biomass (R=0.89, P<0.0001, n=21). Excluding surface O horizons from the analysis, carbon mineralization varied systematically with horizon type (surface A, buried A, buried O, lenses, A/C, B, C) (P<0.05) but not with depth or depth x horizon interaction (overall R2=0.59, P<0.0005, n=47). In contrast to this result and to most published data sets, 13C-to-12C and 15N-to-14N ratios of organic matter declined with depth (13C?26.9 to ?29.3 per mil, 15N+5.6 to ?0.8 per mil). The absence of a relationship between horizon depth and C availability suggests that carbon availability in these buried horizons may be determined by the abundance and quality of organic matter at the time of horizon formation or burial, rather than by duration since burial, and implies that subsurface microbial activity is largely disconnected from surface ecosystems. Our results contribute to the emerging view that buried horizons harbor microbially available C in quantities relevant to ecosystem processes, and suggest that buried C-rich soil horizons need to be incorporated into assessments of the depth of the biologically active zone in near-stream subsurface soils. 相似文献
20.
Junhui Zhang Yanling Hu Xiangming Xiao Pengshi Chen Shijie Han Guozheng Song Guirui Yu 《Agricultural and Forest Meteorology》2009,149(6-7):976-984
Evapotranspiration (ET) is a key flux in the water cycle and has strong seasonal dynamics for forest ecosystems. Recently eddy flux covariance measurements are continuously taken at a temperate mixed forest in Northeastern China since 2002. In an effort to better understanding the factors that control the seasonal dynamics of ET, here we (1) calculate ecosystem-level water use efficiency (WUE) from observed water and CO2 flux data, and (2) relate the resultant WUE with satellite-derived vegetation indices, and (3) develop and evaluate a simple model that uses satellite images and climate data as input data to predict ET on the coupling of photosynthesis and transpiration processes. Ground WUE estimates obtained from eddy covariance tower were correlated with moderate resolution imaging spectroradiometer (MODIS) vegetation indexes (VIs) and ground micrometeorological data over 3 years (2003–2005). The enhanced vegetation index (EVI) was more closely correlated (r = 0.82) with WUE than the normalized difference vegetation index (NDVI; r = 0.64). Air temperature (TA) measured over the canopy was the meteorological variable that was most closely correlated with WUE (r = 0.74) over years. For the significant correlation between EVI and TA (r = 0.82, P < 0.05), EVI was selected as the single variable to predict WUE to simplify calculation. We calculated ET by ET = GPP/WUE, gross primary production (GPP) was predicted by vegetation photosynthesis model (VPM) that uses satellite images and meteorological variables. At a temporal resolution of 8 days, the annual curves showed good correspondence between measured and predicted values of WUE and ET in terms of phase and magnitude for each year. Seasonally integrated predicted ET was +4% (in 2003), +2% (in 2004), +0.4% (in 2005) higher than observed values. 相似文献