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1.
Kaiwen Pan Zhihong Xu Tim Blumfield Shane Totua Manxin Lu 《Journal of Soils and Sediments》2008,8(6):398-405
Background, aim, and scope Hoop pine (Araucaria cunninghamii) is a nitrogen (N) demanding indigenous Australia softwood species with plantations in Southeast Queensland, Australia. Soil
fertility has declined with increasing rotations and comparison study of N cycling between hoop pine plantations, and adjacent
native forest (NF) is required to develop effective forest management for enhancing sustainable forest production and promoting
environmental benefits. Field in situ mineral 15N transformations in these two forest ecosystems have not been studied. Hence, the present study was to compare the differences
in soil nutrients, N transformations, 15N fluxes, and fate between the hoop pine plantation and the adjacent native forest.
Materials and methods The study sites were in Yarraman State Forest (26°52′ S, 151°51′ E), Southeastern Queensland, Australia. The in situ core
incubation method was used in the field experiments. Mineral N was determined using a LACHAT Quickchem Automated Ion Analyzer.
15N were performed using an isotope ratio mass spectrometer with a Eurovector elemental analyzer. All statistical tests were
carried out by the SPSS 11.0 for Windows statistical software package.
Results Soil total C and N were significantly higher in the NF than in the 53-year-old hoop pine plantation. Concentrations of NO3
– were significantly higher in the NF soil than in the plantation soil. The plantation soil had significantly higher 15N and 13C natural abundances than the NF soil. The NF soil had significantly lower C/N ratios than the plantation soil. NO3
––N was dominated in mineral N pools in both NF and plantation soils, accounting for 91.6% and 70.3% of the total mineral N
pools, respectively. Rates of net nitrification and net N mineralization were, respectively, four and three times higher in
the NF soil than in the plantation soil. The 15NO3
––N and mineral 15N were significantly higher in the NF soil than in the plantation soil. Significant difference in 15NH4
+–N was found in the NF soil before and after the incubation.
Discussion The NF soil had significantly higher NO3
––N, mineral N, total N and C but lower δ15N, δ13C, and C/N ratios than the plantation soil. Moreover, the rates of soil net N mineralization and nitrification were significantly
higher, but ammonification rate was lower in the NF than in the plantation. The NF soil had many more dynamic N transformations
than the plantation soil due to the combination of multiple species and layers and, thus, stimulation of microbial activity
and alteration of C and N pool sizes in favor of the N transformations by soil microbes. The net rate of N and 15N transformation demonstrated differences in N dynamic related to the variation in tree species between the two ecosystems.
Conclusions The change of land use and trees species had significant impacts on soil nutrients and N cycling processes. The plantation
had larger losses of N than the NF. The NO3
––N and 15NO3
––N dominated in the mineral N and 15N pools in both forest ecosystems.
Recommendations and perspectives Native forest soil had strong N dynamic compared with the plantation soil. Composition of multiple tree species with different
ecological niches in the plantation could promote the soil ecosystem sustainability. The 15N isotope dilution technique in the field can be quite useful for studying in situ mineral 15N transformations and fate to further understand actual N dynamics in natural forest soils. 相似文献
2.
Wei Zhao Qing Qing Wang Fan Liu Guo Hong Qiu Wen Feng Tan Xiong Han Feng 《Journal of Soils and Sediments》2010,10(5):870-878
Purpose
Lead contamination is ubiquitous, and much attention has been paid due to its toxicity. The phyllomanganate birnessite is the most common Mn oxide in soils. The MnO6 octahedral layers may have significant Mn vacancies in the hexagonal birnessites. Among heavy metal ions, birnessites possess the greatest adsorption affinity and capacity for Pb2+. The aim of this study was to understand the relationship between vacant Mn octahedral sites and Pb2+ adsorption. 相似文献3.
Short-term competition between soil microbes and seedlings of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst.) and silver birch (Betula pendula Roth) for N was assessed in a pot study using (15NH4)2SO4 as a tracer. Seedlings were grown in organic and mineral soil, collected from a podsol soil; 3.18 mg (15NH4)2SO4 per pot were injected into the soil, corresponding to 4 µg 15N g-1 d.m. (dry matter) mineral soil and 17 µg 15N g-1 d.m. organic soil. The amounts of N and 15N in the seedlings and in microbial biomass derived from fumigation-extraction were measured 48 h after addition of 15N. In the mineral soil, 19–30% of the added 15N was found in the plants and 14–20% in the microbial biomass. There were no statistically significant differences between the tree species. In the organic soil, 74% of the added 15N was recovered in the microbial biomass in birch soil, compared to 26% and 17% in pine and spruce soils, respectively. Correspondingly, about 70% of the 15N was recovered in pine and spruce seedlings, and only 23% in birch seedlings. In conclusion, plants generally competed more successfully for added 15NH4 + than soil microbes did. An exception was birch growing in organic soil, where the greater amount of available C from birch root exudates perhaps enabled micro-organisms to utilise more N. 相似文献
4.
Large amounts of C and N are returned to pasture soils by grazing animals in the form of urine and dung. Therefore, a field
trial was carried out to investigate the mid-term effects of 15N-labeled excrements, produced by feeding a cow with 15N-labeled grass silage, on the soil microbial biomass. Simulating the deposition of excrements, 15N-labeled urine and dung were applied to a 0.09-m2 area of a sandy pasture soil in October 2000 and 2001. Applied amounts
of N were 1,030 and 1,052 kg ha−1, respectively. Soil was sampled at 0–15 cm depth, three times over 7 months and analyzed for total C and N, and microbial
biomass C and N. Recovery of urine and dung N in microbial biomass was determined by 15N analysis of K2SO4 extracts of pre-extracted fumigated and unfumigated soils. Under dung patches, microbial biomass C was 16% and 45% higher,
and microbial biomass N was 24% and 57% higher than under the untreated soil in 2001 and 2002, respectively. Under urine patches,
microbial biomass C was increased after 12 weeks and decreased after 27 weeks. Microbial biomass assimilated 7% to 17% and
10% to 21% of the 15N applied initially as urine and dung, respectively. These percentages were considerably higher than those for artificially
with spiked 15N urea-created and labeled manures reported in previous experiments. An important reason may be that the naturally 15N-labeled N components behave differently in soil than urea spikes. 相似文献
5.
Zhiqun Huang Zhihong Xu Timothy J. Blumfield Chengrong Chen Ken Bubb 《Journal of Soils and Sediments》2008,8(6):389-397
Background, aim, and scope
Mulching is frequently used to overcome the drought problem in hardwood plantations that are increasingly being established in lower rainfall areas of Queensland, Australia because of increasing land values. In addition to soil water content, soil nitrogen (N) availability is another critical determinant of plantation productivity in these areas. The purpose of this study was to understand how soil mineral N dynamics, in situ N mineralization, and the fate of fertilized N would be affected by mulching during the early establishment of hardwood plantations. 相似文献6.
Gonzalo Almendros Pilar Tinoco José-María De la Rosa Heike Knicker José-Antonio González-Pérez Francisco J. González-Vila 《Journal of Soils and Sediments》2018,18(4):1303-1313
Purpose
Data management strategies of pyrolysis results and NMR acquisition modes were examined in humic acids (HAs) from control soils and fire-affected soils. The information supplied by dipolar dephasing (DD) 13C NMR spectroscopy and Curie-point pyrolysis were used to assess chemical structures hardly recognizable and measurable, or of unclear interpretation, when using 13C NMR under standard acquisition pulses (cross-polarization/magic angle spinning, CPMAS).Materials and methods
The HAs were isolated from two forest soils under Pinus halepensis and Pinus sylvestris in control and burned sites affected by medium or severe-intensity wildfires. For NMR analyses, during DD acquisition conditions, a 180° 13C pulse was inserted to minimize phase shifts. Curie-Point pyrolysis was carried out at 510 °C for 5 s, and the pyrolysis fragments were analyzed by GC/MS. The total abundances of the major pyrolysis products were compared by an update of the classical Van Krevelen’s graphical-statistical approach, i.e., as surface density values in the space defined by the compound-specific H/C and O/C atomic ratios.Results and discussion
The DD 13C NMR experiments displayed significant differences in the HA spectral profiles as regards to the standard CPMAS 13C NMR acquisition conditions, mainly in the chemical shift region of alkyl structures as well as for tannin- or carbohydrate-like O-alkyl structures. In fact, the comparison between DD and CPMAS solid-state NMR suggested shortening of alkyl chains and generation of carbohydrate-derived, unsaturated structures—viz. furans—which adds to the aromatic domain. Pyrolytic results showed fire-induced specific changes in HAs chemical structure and its molecular diversity. The changes were evident in the location and sizes of the different clusters of pyrolysis compounds defined by their atomic ratios.Conclusions
The DD 13C NMR provided specific information on the fate of aliphatic structures and the origin of unsaturated HA structures, which could be helpful in differentiating “inherited” from “pyrogenic” aromatic structures. This is further confirmed by the analysis of the molecular assemblages of pyrolytic products, which showed accumulation of condensed polyaromatic domains in the HAs after the high-intensity fire, accompanied by a recalcitrant alkyl hydrocarbon domain. Medium-intensity fire led to aromaticity increase due to a selective accumulation of lignin-derived phenols concomitant to the depletion of aliphatic hydrocarbon constituents.7.
In this study, the effects of 1 h aeration, nitrogen gas N2(g) sparging (15 and 30 min) and increasing ferric ions (Fe+3) as FeSO4 (10, 20 and 50 mg L−1) and Fe3O4 nanoparticles (1, 2 and 4 g L−1) concentrations on three less hydrophobic and three more hydrophobic polycyclic aromatic hydrocarbons (PAHs) and toxicity
removals from a petrochemical industry in Izmir (Turkey) were investigated in a sonicator with a power of 650 W and an ultrasound
frequency of 35 kHz; 1 h aeration increased the yields in benzo[b]fluoranthene, benzo[k]fluoranthene and benzo[a]pyrene PAHs (less hydrophobic) from 62% to 67% to around 95–97% after 150 min sonication at 60°C. However, 1 h aeration did
not contribute to the yields of more hydrophobic PAHs (indeno[1,2,3-cd]pyrene, dibenz[a,h]anthracene, benzo[g,h,i]perylene). The maximum yields were obtained at acidic and alkaline pH for more and less hydrophobic PAHs, respectively, after
60 and 120 min sonication at 30°C; 30 min N2(g) sparging, 50 mg L−1 Fe+3 increased the yields of less hydropobic PAHs after 150 min sonication at 60°C. Two milligrams per liter of Fe3O4 nanoparticles increased both less (87–88%) and more (96–98%) hydrophobic PAH yields. The Daphnia magna acute toxicity test showed that the toxicity decreased significantly with an hour aeration, 30 min N2(g) sparging, 50 mg L−1 Fe+3 and 2 g L−1 Fe3O4 nanoparticles at 60°C after 120 and 150 min sonications. Vibrio fischeri was found to be more resistant to the sonicated samples than D. magna. Significant correlations were found between the physicochemical properties of sonicated PAHs and acute toxicities both organisms. 相似文献
8.
Yasser Mahmoud Awad Johanna Pausch Yong Sik Ok Yakov Kuzyakov 《Journal of Soils and Sediments》2017,17(3):621-631
Purpose
The applications of biochar (BC) and polyacrylamide (PAM) may have interactive effects on carbon (C) dynamics and sequestration for improving the soil quality and achieving sustainable agriculture. Relative to BC and PAM, rhizodeposits act as C and energy source for microorganisms and may change the mineralization dynamics of soil organic matter (SOM). No attempt has been made to assess the effects of BC, anionic PAM, or their combination on the decomposition of different aged 14C-labeled rhizodeposits. The objective of this study was to investigate the effects of the treatments mentioned above on the decomposition of different aged 14C-labeled maize rhizodeposits.Materials and methods
biochar (BC) at 10 Mg ha?1 or anionic PAM at 80 kg ha?1 or their combination (BC + PAM) was applied to soils with/without 2-, 4-, 8-, and 16-day-aged 14C-labeled maize rhizodeposits. After that, the soil was incubated at 22 °C for 46 days.Results and discussion
After 2 days of incubation, the total CO2 efflux rates from the soil with rhizodeposits were 1.4–1.8 times higher than those from the soil without rhizodeposits. The cumulative 14CO2 efflux (32 % of the 14C input) was maximal for the soil containing 2-day-aged 14C-labeled rhizodeposits. Consequently, 2-day-aged rhizodeposits were more easily and rapidly decomposed than the older rhizodeposits. However, no differences in the total respired 14CO2 from rhizodeposits were observed at the end of the incubation. Incorporation of 14C into microbial biomass and 66–85 % of the 14C input remained in the soil after 46 days indicated that neither the age of 14C-labeled rhizodeposits nor BC, PAM, or BC + PAM changed microbial utilization of rhizodeposits.Conclusions
Applying BC or BC + PAM to soil exerted only minor effects on the decomposition of rhizodeposits. The contribution of rhizodeposits to CO2 efflux from soil and MBC depends on their age as young rhizodeposits contain more labile C, which is easily available for microbial uptake and utilization.9.
Alberto Agnelli Judith Ascher Giuseppe Corti Maria Teresa Ceccherini Giacomo Pietramellara Paolo Nannipieri 《Biology and Fertility of Soils》2007,44(2):353-361
The aim of this work was to obtain pure extracellular DNA molecules so as to estimate their longevity in soil by an isotope-based
approach. Extracellular DNA molecules were extracted from all horizons of a forest soil and purified by the procedure of Davis
(Purification and precipitation of genomic DNA with phenol–chloroform and ethanol. In: Davis LG, Dibner MD, Battey JF (eds)
Basic methods in molecular biology. Appleton & Lange, Norwalk, 16–22, 1986) without (DNA1) or with (DNA2) a successive treatment with binding resins followed
by elution. The two differently purified DNA samples were compared for their A260/A280 ratio, polymerase chain reaction (PCR) amplification and natural abundance of stable (13C and 15N) and radioactive (14C) isotopes. The purity index and the PCR amplification did not differentiate the efficiency of the two purification procedures.
The isotopic signature of DNA was more sensitive and was strongly affected by the purification procedures. The isotopic measurements
showed that the major contaminant of extracellular DNA1 was the soil organic matter (SOM), even if it is not possible to exclude
that the similar δ
13C, δ
15N and Δ14C values of DNA and SOM could be due to the use of SOM-deriving C and N atoms for the microbial synthesis of DNA. For extracellular
DNA2, extremely low values of Δ14C were obtained, and this was ascribed to the presence of fossil fuel-derived substances used during the purification, although
in amounts not revealed by gas chromatography-mass spectrometry analysis. The fact that it is not possible to obtain contaminant-free
DNA molecules and the potential use of soil native organic compounds during the microbial synthesis of DNA make it not achievable
to estimate the age of soil extracellular DNA by radiocarbon dating. 相似文献
10.
Yasser Mahmoud Awad Sang Soo Lee Yong Sik Ok Yakov Kuzyakov 《Journal of Soils and Sediments》2017,17(3):611-620
Purpose
Various soil conditioners, such as biochar (BC) and anionic polyacrylamide (PAM), improve soil fertility and susceptibility to erosion, and may alter microbial accessibility and decomposition of soil organic matter (SOM) and plant residues. To date, no attempts have been made to study the effects of BC in combination with PAM on the decomposition of soil SOM and plant residues. The objective of this study was to evaluate the effects of BC, PAM, and their combination on the decomposition of SOM and alfalfa residues.Materials and methods
An 80-day incubation experiment was carried out to investigate the effects of oak wood biochar (BC; 10 Mg ha?1), PAM (80 kg ha?1), and their combination (BC?+?PAM) on decomposition of SOM and 14C-labeled alfalfa (Medicago sativa L.) residues by measuring CO2 efflux, microbial biomass, and specific respiration activity.Results and discussion
No conditioner exerted a significant effect on SOM decomposition over the 80 days of incubation. PAM increased cumulative CO2 efflux at 55–80 days of incubation on average of 6.7 % compared to the soil with plant residue. This was confirmed by the increased MBN and MB14C at 80 days of incubation in PAM-treated soil with plant residue compared to the control. In contrast, BC and BC?+?PAM decreased plant residue decomposition compared to that in PAM-treated soil and the respective control soil during the 80 days. BC and BC?+?PAM decreased MBC in soil at 2 days of incubation indicated that BC suppressed soil microorganisms and, therefore, decreased the decomposition of plant residue.Conclusions
The addition of oak wood BC alone or in combination with PAM to soil decreased the decomposition of plant residue.11.
Alice Bosco-Santos Wanilson Luiz-Silva Elton Luiz Dantas 《Water, air, and soil pollution》2018,229(11):365
This study tested for the first time 147Sm/144Nd and 143Nd/144Nd ratios as tracers of rare earth element (REE) sources in semi-terrestrial organisms from a subtropical estuary affected by fertilizer industry activities. The isotopic composition of claw muscles and shells of male crabs (Ucides cordatus) were obtained by thermal ionization mass spectrometry, and provided contrasting signatures incorporated from the physical components by the biota. Our findings showed that crab shells had isotopic compositions similar to seawater, while the claw muscles incorporated the isotopic signature of sediments contaminated by fertilizer. The isotopic ratios (147Sm/144Nd and 143Nd/144Nd) proved that the anthropogenic source is transferring contaminants to the crabs, emerging as a reliable tool to diagnose REE pathway and source to the biota in impacted environments. 相似文献
12.
A laboratory incubation experiment was conducted to demonstrate that reduced availability of CO2 may be an important factor limiting nitrification. Soil samples amended with wheat straw (0%, 0.1% and 0.2%) and (15NH4)2SO4 (200 mg N kg–1 soil, 2.213 atom% 15N excess) were incubated at 30±2°C for 20 days with or without the arrangement for trapping CO2 resulting from the decomposition of organic matter. Nitrification (as determined by the disappearance of NH4+ and accumulation of NO3–) was found to be highly sensitive to available CO2 decreasing significantly when CO2 was trapped in alkali solution and increasing substantially when the amount of CO2 in the soil atmosphere increased due to the decomposition of added wheat straw. The co-efficient of correlation between NH4+-N and NO3–-N content of soil was highly significant (r =0.99). During incubation, 0.1–78% of the applied NH4+ was recovered as NO3– at different incubation intervals. Amendment of soil with wheat straw significantly increased NH4+ immobilization. From 1.6% to 4.5% of the applied N was unaccounted for and was due to N losses. The results of the study suggest that decreased availability of CO2 will limit the process of nitrification during soil incubations involving trapping of CO2 (in closed vessels) or its removal from the stream of air passing over the incubated soil (in open-ended systems). 相似文献
13.
Background, aim and scope
This paper discusses a method investigating the reduction of free heavy metal cation contents in soil through the use of microbe-inducing precipitate (MIP). 相似文献14.
Bangliang Deng Zhenzhen Li Ling Zhang Yingchao Ma Zhi Li Wenyuan Zhang Xiaomin Guo Dekui Niu Evan Siemann 《Journal of Soils and Sediments》2016,16(3):777-784
Purpose
Ecosystem restorations can impact carbon dioxide (CO2) and nitrous oxide (N2O) emissions which are important greenhouse gasses. Alpine meadows are degraded worldwide, but restorations are increasing. Because their soils represent large carbon (C) and nitrogen (N) pools, they may produce significant amounts of CO2 and N2O depending on the plant species used in restorations. In addition, warming and N deposition may impact soil CO2 and N2O emissions from restored meadows.Materials and methods
We collected soils from degraded meadows and plots restored using three different plant species at Wugong Mountain (Jiangxi, China). We measured CO2 and N2O emissions when soils were incubated at different temperatures (15, 25 or 35 °C) and levels of N addition (control vs. 4 g m?2) to understand their responses to warming and N deposition.Results and discussion
Dissolved organic C was higher in restored plots (especially with Fimbristylis dichotoma) compared to non-restored bare soils, and their soil inorganic N was lower. CO2 emission rates were increased by vegetation restorations, decreased by N deposition, and increased by warming. CO2 emission rates were similar for the three grass species at 15 and 25 °C, but they were lower with Miscanthus floridulus at 35 °C. Soils from F. dichotoma and Carex chinensis plots had higher N2O emissions than degraded or M. floridulus plots, especially at 25 °C.Conclusions
These results show that the effects of restorations on soil greenhouse gas emissions depended on plant species. In addition, these differences varied with temperature suggesting that future climate should be considered when choosing plant species in restorations to predict soil CO2 and N2O emissions and global warming potential.15.
We assessed the effect of liming on (1) N2O production by denitrification under aerobic conditions using the 15N tracer method (experiment 1); and (2) the reduction of N2O to N2 under anaerobic conditions using the acetylene inhibition method (experiment 2). A Mollic Andosol with three lime treatments (unlimed soil, 4 and 20 mg CaCO3 kg?1) was incubated at 15 and 25 °C for 22 days at 50% and then 80% WFPS with or without 200 mg N kg?1 added as 15N enriched KNO3 in experiment 1. In experiment 2, the limed and unlimed soils were incubated under completely anaerobic conditions for 44 h (with or without 100 mg N kg?1 as KNO3). In experiment 1, limed treatments increased N2O fluxes at 50% WFPS but decreased these fluxes at 80% WFPS. At 25 °C, cumulative N2O and 15N2O emissions in the high lime treatment were the lowest (with at least 30% less 15N2O and total N2O than the unlimed soil). Under anaerobic conditions, the high lime treatment showed at least 50% less N2O than the unlimed treatment at both temperatures with or without KNO3 addition but showed enhanced N2 production. Our results suggest that the positive effect of liming on the mitigation of N2O evolution from soil was influenced by soil temperature and moisture conditions. 相似文献
16.
Alternative silvicultural systems were introduced in Coastal Western Hemlock forests of British Columbia, Canada, to reduce
disturbance incurred by conventional clear-cutting and to maintain the forest influence on soil nutrient cycling. As we hypothesized,
in situ pools and net mineralization of NH4
+ were lower under no and low disturbance (old-growth forest and shelterwood) compared to clear-cuts (high disturbance); in
situ pools and net production of NO3
− were very low across all treatments. Gross transformation rates of NH4
+ increased while those of NO3
− decreased with increasing disturbance, suggesting that these processes were uncoupled. We conclude that shelterwood harvesting
reduces the impact on forest floor NH4
+ cycling compared to clear-cutting, and that neither low nor high disturbance intensity results in substantial NO3
− accumulation, as what occasionally occurs in other ecosystems. We hypothesize that the uncoupling of NH4
+ and NO3
− dynamics may be due to the predominance of heterotrophic nitrification by lignin-degrading fungi that oxidize organic N rather
than NH4
+–N, and whose activities are suppressed at high NH4
+ concentrations. 相似文献
17.
B. F. Aparin E. V. Mingareeva N. I. Sanzharova E. Yu. Sukhacheva 《Eurasian Soil Science》2017,50(12):1395-1405
Data on the concentrations of natural (226Ra, 232Th and 40K) and artificial (137Cs) radionuclides and on the physicochemical properties of chernozems sampled in different years are presented. In 1952, upon the creation of the Penza-Kamensk state shelterbelt, three deep (up to 3 m) soil pits were examined within the former arable field under two-year-old plantations of ash and maple along the transect crossing the territory of the Beloprudskaya Experimental Station of the USSR Academy of Sciences in Volgograd oblast. The samples from these pits were included into the collection of dated soil samples of the Dokuchaev Central Soil Science Museum. Five pits were examined along the same transect in 2009: three pits under shelterbelts (analogues of the pits studied in 1952) and two pits on arable fields between the shelterbelts. In the past 57 years, certain changes took place in the soil structure, bulk density, and the content and composition of humus. The salt profile of soils changed significantly under the forests. The comparison of distribution patterns of natural soil radionuclides in 1952 and 2009 demonstrated their higher contents at the depth of 10–20 cm in 2009 (except for the western shelterbelt). Background concentrations of natural radionuclides in parent materials and relationships between their distributions and the salt profiles of soils have been determined; they are most clearly observed is the soils under shelterbelts. Insignificant contamination with 137Cs (up to 34 Bq/kg) has been found in the samples of 2009 from the upper (0–20 cm) horizon. The activity of 137Cs regularly decreases from the east to the west; the highest concentrations of this radionuclide are found in the topmost 10 cm. This allows us to suppose that 137Cs was brought with aerial dust by eastern winds, and the shelterbelts served as barriers to the wind flow. 相似文献
18.
Nitrogen transformation rates and N<Subscript>2</Subscript>O producing pathways in two pasture soils
Ting Lan Helen Suter Rui Liu Xuesong Gao Deli Chen 《Journal of Soils and Sediments》2018,18(9):2970-2979
Purpose
Better understanding of N transformations and the regulation of N2O-related N transformation processes in pasture soil contributes significantly to N fertilizer management and development of targeted mitigation strategies.Materials and methods
15N tracer technique combined with acetylene (C2H2) method was used to measure gross N transformation rates and to distinguish pathways of N2O production in two Australian pasture soils. The soils were collected from Glenormiston (GN) and Terang (TR), Victoria, Australia, and incubated at a soil moisture content of 60% water-filled pore space (WFPS) and at temperature of 20 °C.Results and discussion
Two tested pasture soils were characterized by high mineralization and immobilization turnover. The average gross N nitrification rate (ntot) was 7.28 mg N kg?1 day?1 in TR soil () and 5.79 mg N kg?1 day?1 in GN soil. Heterotrophic nitrification rates (nh), which accounting for 50.8 and 41.9% of ntot, and 23.4 and 30.1% of N2O emissions in GN and TR soils, respectively, played a role similar with autotrophic nitrification in total nitrification and N2O emission. Denitrification rates in two pasture soils were as low as 0.003–0.004 mg N kg?1 day?1 under selected conditions but contributed more than 30% of N2O emissions.Conclusions
Results demonstrated that two tested pasture soils were characterized by fast N transformation rates of mineralization, immobilization, and nitrification. Heterotrophic nitrification could be an important NO3?–N production transformation process in studied pasture soils. Except for autotrophic nitrification, roles of heterotrophic nitrification and denitrification in N2O emission in two pasture soils should be considered when developing mitigation strategies.19.
Kwang Seop Kim Man Park Choong Lyeal Choi Dong Hoon Lee Young Jin Seo Chan Yong Kim Jong Su Kim Seok-In Yun Hee-Myong Ro Sridhar Komarneni 《Journal of Soils and Sediments》2011,11(3):416-422
Purpose
A large amount of nitrogen (N) fertilizers has been broadcasted over soil surface for reliable crop production. Unfortunately, the broadcasted N vulnerable to volatilization and leaching can lead to serious environmental problems. As a new approach to mitigate N loss of broadcasted fertilizers, massive intercalation of urea into montmorillonite (MMT) was recently proposed to innovatively enhance the urea use efficiency. This study focuses on demonstrating the behaviors of the urea intercalated into MMT in soils. 相似文献20.
Fangfang Sun Yuanwen Kuang Dazhi Wen Zhihong Xu Jianli Li Weidong Zuo Enqing Hou 《Journal of Soils and Sediments》2010,10(8):1453-1465