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1.
Yun Zhang Zhichao Wei Huitong Li Futao Guo Pengfei Wu Lili Zhou Xiangqing Ma 《Journal of Soils and Sediments》2017,17(9):2218-2229
Purpose
Biochemical protection is an important mechanism for maintaining the long-term stability of the soil carbon (C) pool. The labile and recalcitrant pools of soil organic matter (SOM) play different roles in regulating C and N dynamics; however, few studies have characterized the capacity of soil C sequestration while considering the biochemical quality of SOM. The aim of the present study was to assess the changes in the soil organic carbon (SOC) and nitrogen (N) pools during a traditional rotation period (25 years) of a Chinese fir (Cunninghamia lanceolata) plantation with an emphasis on SOM biochemical quality.Materials and methods
Three different forest stand development stages—young (6 years old), middle-aged (16 years old) and mature (25 years old)—were selected for soil sampling to a depth of 100 cm. Total C and total N of the soil was analysed to determine the changes in the SOC and N stocks among the three development stages using an equivalent soil mass (ESM) approach. Bulk soils were fractionated into labile and recalcitrant fractions using the acid hydrolysis method to identify the quality of SOM.Results and discussion
The mineral soil organic carbon pool at a 1-m depth slightly decreased from the young stand to the middle-aged stand and rapidly increased by 28 % to reach a maximum in the mature stand. SOC accumulation in the surface soil predominated the changes in total SOC stocks in all three stands. The increased N was reflected in the entire depth, and the highest soil N accumulation was in the mature stand. The recalcitrant C concentration and SOC were positively correlated. The non-hydrolysable C proportion was lower in the middle-aged stand versus the young stand (8.69 % loss), while the labile C percentage was higher (13.89 % gain). In the mature stand, the recalcitrant C index increased to 39.84 %. The recalcitrant index of C decreased with an increasing soil depth, whereas the recalcitrant index of N dramatically increased.Conclusions
These results highlighted the significant effect of the stand age and the soil depth on the storage and biochemical availability of SOM in Chinese fir plantations of southern China. The recalcitrant index of C changed with the change in SOC concentration, indicating that biochemical protection mechanism plays an important role in soil C sequestration. In addition, more attention should be paid to subsoil C protection in the management of Chinese fir plantations because of low biochemical stability.2.
Purpose
Microbial decomposition of soil organic matter (SOM) is generally believed to be heterogeneous, resulting in the preferential loss of labile compounds such as carbohydrates and proteins and the accumulation of recalcitrant compounds such as lipids and lignin. However, these fractions are difficult to measure directly in soils. We examined patterns in the biomolecular composition of SOM and hot-water-extractable organic matter (HWEOM) by using a molecular mixing model (MMM) to estimate the content of carbohydrates, protein, lipids, and lignin.Materials and methods
Organic-horizon soils from Spodosols at the Hubbard Brook Experimental Forest in NH, USA were analyzed for this study. The MMM uses data from elemental analysis (C, H, and N) and 13C nuclear magnetic resonance spectroscopy with cross-polarization and magic-angle spinning to estimate the percentage of total C in the various classes of biomolecules.Results and discussion
Carbohydrate content decreased from about 50 % of the C in recent litter to approximately 35 % in the bottom of the humus layer. Lipids accounted for about 18 % of C in recent litter and increased to 40 % in the lower humus layers. The HWEOM fraction of SOM was dominated by carbohydrates (40–70 % of C). Carbohydrates and lipids in HWEOM exhibited depth patterns that were the opposite of the SOM. The results from the MMM confirmed the selective decomposition of carbohydrates and the relative accumulation of lipids during humus formation. The depth patterns in HWEOM suggest that the solubility of carbohydrates increases during decomposition, while the solubility of the lipid fraction decreases. The MMM was able to reproduce the spectral properties of SOM and HWEOM very accurately, although there were some discrepancies between the predicted and measured H/C and O/C ratios.Conclusions
The MMM approach is an accurate and cost-effective alternative to wet-chemical methods. Together, carbohydrates and proteins account for up to 85 % of the C in HWEOM, indicating that the HWEOM fraction represents a labile source of C for microbes. Humification resulted in a decrease in carbohydrate content and an increase in lipids in SOM, consistent with investigations carried out in diverse soil environments. 相似文献3.
Maokui Lyu Jinsheng Xie Liisa Ukonmaanaho Miaohua Jiang Yiqing Li Yuehmin Chen Zhijie Yang Yanxiang Zhou Weisheng Lin Yusheng Yang 《Journal of Soils and Sediments》2017,17(9):2305-2317
Purpose
It has been widely recognized that land use changes can cause significant alterations of soil organic matter (SOM) of various ecosystems. Forest conversion, a common land use change, and its effects on SOM have been a hot research topic during the past two decades. However, the mechanisms of the effects of forest conversion on SOM dynamics, particularly in deep soils, largely remain uncertain. This study aimed to examine the impacts of forest conversion on SOM stabilization through the analysis of soil aggregate and density fractionation, microbial composition, and functions in deep soils.Materials and methods
Soil C and microbes were sampled in soil layers of 0–20 and 60–80 cm under broadleaved secondary forest and two coniferous plantations (Cunninghamia lanceolata and Pinus massoniana). Aggregate and density fractionation techniques were used to analyze C accumulation in non-protected, physically, chemically, and biochemically protected C fractions. A 90-day laboratory mineralization incubation experiment with and without 400-mg C kg?1 soil glucose and phenol was conducted to determine the potential mineralizable C, utilization of substrate capacity, and metabolic quotient (qCO2).Results and discussion
Conversion of secondary forests into coniferous plantations significantly decreased bulk soil C, especially in the deep soils. Forest conversion significantly decreased non-protected, physically, and chemically protected C fractions in both topsoil and deep soil and biochemically protected C fraction in deep soils. The soil organic carbon (SOC) of topsoils was dominated by non-protected fraction while in deep soil which was dominated by protected fraction. Compared with the topsoils, soil microbes in the deep soils tend to preferentially use labile soil organic matter with lower substrate use efficiency (higher values of qCO2), which indicates that a r-strategy dominates of microbes. The increased respiration rate in the deep soils caused by forest conversion, when normalized to soil C, indicates that deep SOM may be more prone to decomposition and destabilization than top SOM.Conclusions
Forest conversion can cause a significant alteration of SOC stabilization through the changes of physically, chemically, and biochemically protected SOC fractions. The mechanisms for the changes in non-protected or/and protected SOC fractions may be associated with the redistribution of r-strategy- and K-strategy-dominated microbes due to changes in litter inputs and priming effects.4.
Lei Wang Clayton R. Butterly Wei Tian Herath M. S. K. Herath Yunguan Xi Jibing Zhang Xingji Xiao 《Journal of Soils and Sediments》2016,16(7):1933-1943
Purpose
To better understand the effect of fertilizer practices on soil acidification and soil organic matter (SOM) stocks in a rice-wheat system, a field experiment was conducted to (i) investigate the influence of fertilizer practices on the Al forms in solid phases and the distribution of Al species in water extracts and (ii) explore the relationship between the Al forms, the quantity and composition of SOM, and soil acidity.Materials and methods
Seven fertilizer treatments including CL (no fertilizer), NK, PK, NPK, N2PK (PK and 125 % of N), NP2K (NK and 125 % of P), and organic fertilizer (OF) were applied to induce various changes in pH and SOM composition (i.e., total C and N contents, C/N ratio, and SOM recalcitrant indices) in a rice-wheat system. After 6-year cultivation, different pools of Al forms (i.e., amorphous Al; organically bound Al of varying stability; exchangeable Al; water-soluble inorganic Al3+, Al-OH, Al-F, Al-SiO3, and Al-SO4; and organic Al monomers) were quantified and related with SOM composition and soil pH during the wheat phase.Results and discussion
Fertilizer types significantly changed soil pH and SOM composition and which explained 84 % of the variance of Al forms using redundancy analysis. An interaction between soil pH and SOM quality on Al forms also existed but only accounted for a very small (6 %) portion of the variation. Compared to CL and chemical fertilizer, OF practice with relative low SOM stabilization is likely to favor the formation of amorphous Al in order to bind more SOM. The decrease in exchangeable acidity and water-extractable Al via hydroxyl-Al precipitation but not in the form of organo-aluminum complexes evidenced this phenomenon. In contrast, chemical fertilizer input increased exchangeable Al and water extract Al (especially Al3+), partly at the expense of organically bound Al. The destabilization of organic-aluminum complexes was a mechanism of pH buffering evidenced by the increased soluble Al-dissolved organic matter (DOM) as soil pH decreases. Further, the magnitude of this trend was much greater for elevated N input compared with P input.Conclusions
Chemical fertilizer with relative high SOM stabilization favored the formation of exchangeable Al and soluble Al resulting in soil acidification, whereas OF with relative low SOM stabilization tended to transform exchangeable Al and soluble Al to amorphous Al, thereby alleviating soil acidification and enhancing C stocks in a rice-wheat system.5.
Nora Polláková Vladimír Šimanský Miroslav Kravka 《Journal of Soils and Sediments》2018,18(8):2790-2800
Purpose
Because the stability of soil aggregates is affected by many factors, we studied aggregates formed in forest and agricultural soils in different soil types (Cambisols, Luvisols, Chernozems). We evaluated: (1) the differences in water-stable aggregates (WSA) as related to soil type and land management and (2) the relationships between quantitative and qualitative parameters of soil organic matter (SOM), particle-size distribution and individual size classes of WSA.Materials and methods
Soil samples were taken from three localities (Sobě?ice, Báb, Vieska nad ?itavou). Each study locality included both a forest and an agricultural soil-sampling area.Results and discussion
We found that in forest soils, the proportion of water-stable macroaggregates (WSAma) relative to water-stable microaggregates (WSAmi) was greater than in agricultural soils. When all soils were assessed together, positive statistically significant correlations were observed between the size classes WSAma > 1 mm and organic carbon (Corg) content; however, the WSAmi content was negatively correlated with Corg content. Favorable humus quality positively influenced the stabilization of WSAma > 5 mm; however, we found it had a negative statistically significant effect on stabilization of WSAma 1–0.25 mm. In agricultural soils, the stabilization of WSAma was associated with humified, i.e., stable SOM. The WSAma content was highly positively influenced mainly by fulvic acids bound with clay and sesquioxides; therefore, we consider this humus fraction to be a key to macroaggregate stability in the studied agricultural soils. On the other side, all fractions of humic and fulvic acids participated on the formation of WSAma in forest soil, which is a major difference in organic stabilization agents of macroaggregates between studied forest and agricultural soils. Another considerable difference is that WSAmi in agricultural soils were stabilized primarily with humic acids and in forest soils by fulvic acids. Moreover, in forest soils, a higher content of labile carbon in WSA had a positive effect on formation of WSAmi.Conclusions
The observed changes in individual size classes of WSA and interactions between SOM, particle-size distribution, and WSA have a negative impact on soil fertility and thereby endanger agricultural sustainability.6.
Giorgio S. Senesi Ladislau Martin-Neto Paulino Ribeiro Villas-Boas Gustavo Nicolodelli Débora M. B. P. Milori 《Journal of Soils and Sediments》2018,18(4):1292-1302
Purpose
The objective of this review is to survey critically the results obtained by the application of laser-induced fluorescence spectroscopy (LIFS) and laser-induced breakdown spectroscopy (LIBS) to the evaluation of the humification degree (HD) of soil organic matter (SOM) directly in untreated, intact whole soils.Materials and methods
A large number of soils of various origin and nature, either native or under various cultivations, land use, and management, at various depths, have been studied to evaluate the HD of their SOM directly in intact whole samples. The LIFS spectra were obtained by either a bench or a portable argon laser apparatus that emits UV-VIS light of high power, whereas the LIBS spectra were obtained using a Q-switched Nd:YAG laser at 1064 nm.Results and discussion
The close correlations found by comparing HLIF values of whole soil samples with values of earlier proposed humification indexes confirmed the applicability of LIFS to assess the HD of SOM in whole soils. The high correlation found between HDLIBS values and HLIF values showed the promising potential of LIBS for the evaluation HD of SOM.Conclusions
The LIFS technique shows to be a valuable alternative to evaluate the HD of SOM by probing directly the whole solid soil sample, thus avoiding the use of any previous chemical and/or physical treatments or separation procedures of SOM from the mineral soil matrix. The emerging application of LIBS to evaluate the HD of SOM in whole soils appears promising and appealing due to its sensitivity, selectivity, accuracy, and precision.7.
Soil organic matter evolution after the application of high doses of organic amendments in a Mediterranean calcareous soil 总被引：1，自引：0，他引：1
Sergio González-Ubierna Ignacio Jorge-Mardomingo Beatriz Carrero-González María Teresa de la Cruz Miguel ángel Casermeiro 《Journal of Soils and Sediments》2012,12(8):1257-1268
Purpose
We investigate the coevolution of soil organic matter (SOM) and soil properties in a semiarid Mediterranean agroecosystem, as well as the 1-year evolution of the different pools of soil organic and inorganic carbon and their influence on soil respiration after the application of a single high dose of three different organic amendments.Material and methods
We applied a single high dose (160?Mg?ha?1 in dry weight (DW)) of three types of organic amendments: aerobically digested sewage sludge (AE), anaerobically digested sewage sludge (AN), and municipal solid waste compost (MSWC), in a calcareous Mediterranean soil. The study area is located in the southeast of Madrid (Spain), characterized by a Mediterranean climate with a marked seasonal and daily contrast. We analyzed different forms of soil organic and inorganic carbon and soil respiration rates. The measurements have been performed quarterly for 1?year.Results and discussion
The results showed that the coevolution of SOM and soil largely depends on the origin and composition of the organic amendments used. The AN sludge affected the soil chemistry more. The organic matter (OM) provided by AE treatments underwent more intense mineralization processes than AN, with the OM from MSWC being more stable. This behavior could be explained by the different pools of carbon involved in each case. The treatments contributed differently to soil respiration rates following the sequence: AE > AN > MSWC. The application of organic amendments in calcareous Mediterranean soils also modified the inorganic carbon pools.Conclusions
SOM and soil coevolution after organic amendments application depends on the origin and chemical composition of the inputs. The decision-making process of urban organic waste application with regard to agricultural policy must take into account the different behavior in soil of the different types of amendments. 相似文献8.
Electron transfer capacity of soil dissolved organic matter and its potential impact on soil respiration 总被引：1，自引：0，他引：1
Purpose
Soil dissolved organic matter (DOM) as the labile fraction of soil organic carbon (SOC) is able to facilitate biogeochemical redox reactions effecting soil respiration and carbon sequestration. In this study, we took soil samples from 20 sites differing in land use (forest and agriculture) to investigate the electron transfer capacity of soil DOM and its potential relationship with soil respiration.Materials and methods
DOM was extracted from 20 soil samples representing different land uses: forest (nos. 1–12) and agriculture (nos. 13–20) in Guangdong Province, China. Chronoamperometry was employed to quantify the electron transfer capacity (ETC) of the DOM, including electron acceptor capacity (EAC) and electron donor capacity (EDC), by applying fixed positive or negative potentials to a working electrode in a conventional three-electrode cell. The reversibility of electron accepting from or donating to DOM was measured by applying switchable potentials to the working electrode in the electrochemical system with the multiple-step potential technique. Carbon dioxide produced by soil respiration was measured with a gas chromatograph.Results and discussion
Forest soil DOM samples showed higher ETC and electron reversible rate (ERR) than agricultural soil DOM samples, which may be indicative of higher humification rate and microbial activity in forest soils. The average soil respiration of forest soil (nos. 1–12) and agricultural soil (nos. 13–10) was 26.34 and 18.58 mg C g?1 SOC, respectively. Both EDC and EAC of soil DOM had close relationship with soil respiration (p?<?0.01). The results implied that soil respiration might be accelerated by the electroactive moieties contained in soil DOM, which serve as electron shuttles and facilitate electron transfer reactions in soil respiration and SOC mineralization.Conclusions
DOM of forest soils showed higher ETC and ERR than DOM of agricultural soils. As soil represents one of the largest reservoirs of organic carbon, soil respiration affects C cycle and subsequently CO2 concentration in the atmosphere. As one of the important characteristics of soil DOM related to soil respiration, ETC has a significant impact on greenhouse gas emission and soil carbon sequestration but has not been paid attention to. 相似文献9.
Purpose
Carbon (C) flux is largely controlled by the highly bio-reactive labile C (LC) pool, while long-term C storage is determined by the recalcitrant C (RC) pool. Soil nitrogen (N) availability may considerably affect changes of these pools. The aim of this study was to investigate the effects of N treatments on soil LC and RC pools.Materials and methods
A field experiment was conducted in a city lawn soil for 600 days with three N treatments, i.e., the control (0 kg N ha?1 year?1), low-N (100 kg N ha?1 year?1), and high-N (200 kg N ha?1 year?1) treatments. As the N source, NH4NO3 solution was added to soil surface monthly. Measurements of LC, RC, and other soil biochemical properties, including pH, soil respiration rates, microbial biomass, and enzymes activities, were taken during the experiment period.Results and discussion
The low-N and high-N treatments increased 6.3 and 13% of the LC pool, respectively, which was caused by decreased microbial biomass and soil respiration rates under the N treatments. By contrary, the low-N and high-N treatments decreased 5.9 and 12% of the RC pool, respectively. The N addition treatments enhanced phenol oxidase activities. The enhanced oxidase activities decreased new RC input and the increased dissolved organic C stimulated RC pool decomposition. The LC and RC pools were highly influenced by the N treatments, whereas effect of the N treatments on soil organic C was not significant. The N addition treatments also caused soil acidification and reduced bacterial biomass proportion in the soil microbial composition.Conclusions
The N addition increased the LC pool but decreased the RC pool in the soil. These changes should greatly impact soil long-term C storage. 相似文献10.
Short-term evolution of hydration effects on soil organic matter properties and resulting implications for sorption of naphthalene-2-ol 总被引：1，自引：1，他引：0
Tatjana Schneckenburger Gabriele E. Schaumann Susanne K. Woche S?ren Thiele-Bruhn 《Journal of Soils and Sediments》2012,12(8):1269-1279
Purpose
Sorption of xenobiotics in soils and especially to soil organic matter (SOM) determines their mobility and bioavailability in ecosystems. However, SOM as the major sorbent may be altered in its physicochemical properties upon changes in boundary conditions such as hydration. Hence, the goal of this study was to determine the influence of soil hydration on physicochemical properties of SOM and the resulting effects on sorption of xenobiotics.Materials and methods
Samples of a Histosol with 51?% SOM were adjusted to five water contents from 10 to 75?% (w/w based on dry soil mass) and aged for water contact times of 0?weeks to 3?years. The hydrated samples were characterized with respect to thermal properties of SOM and of the incorporated water via differential scanning calorimetry and with respect to hydration-induced swelling via 1H-NMR relaxometry, and the sessile drop method was applied to determine their soil?Cwater contact angle. Sorption kinetics and isotherms of naphthalene-2-ol in the pre-treated peat samples were determined in batch experiments.Results and discussion
SOM matrix rigidity varied with the water content and increased with water contact time. An initial minimum in SOM rigidity at ~30?% water content became maximum after ~20?weeks, also resulting in the strongest resistance towards water infiltration. We argue that the anomalies at 30?% water content are related to the critical water content for the formation of freezable water w crit in the peat samples, which was 26.2?±?0.3?%. Conditions for water-assisted molecular bridging were assumably optimal at 30?% water content. Whereas parameters of naphthalene-2-ol sorption reflecting the sorbed amount were mainly altered by the wetting properties of SOM, sorption linearity and hysteresis were influenced by the anomalies in peat matrix properties at a water content around 30?%.Conclusions
The study revealed that the interplay of SOM and water led to highly variable and complex changes in SOM physicochemical properties. These properties may serve as a predictor for sorption of xenobiotics in soil at varying hydration conditions enabling a more precise assessment of the environmental fate of xenobiotics. 相似文献11.
Stability and saturation of soil organic carbon in rice fields: evidence from a long-term fertilization experiment in subtropical China 总被引：1，自引：1，他引：0
Purpose
Soil organic carbon (SOC) sequestration in croplands plays a critical role in climate change mitigation and food security, whereas the stability and saturation of the sequestered SOC have not been well understood yet, particularly in rice (Oryza sativa L.) fields. The objective of this study was to determine the long-term effect of inorganic fertilization alone or combined with organic amendments on SOC stability in a double rice cropping system, and to characterize the saturation behavior of the total SOC and its fractions in the paddy soil.Materials and methods
Soils were collected from a long-term field experiment in subtropical China where different fertilization regimes have been carried out for 31 years. The total SOC pool was separated into four fractions, characteristic of different turnover rates through chemical fractionation. Annual organic carbon (C) inputs were also estimated by determining the C content in crop residues and organic amendments.Results and discussion
Relative to the initial level, long-term double rice cropping without any fertilizer application significantly increased SOC concentration, suggesting that double rice cropping facilitates the storage and accumulation of SOC. The partial substitution of inorganic fertilizers with organic amendments significantly increased total SOC concentration compared to the unfertilized control. Total SOC increased significantly with greater C inputs and did not show any saturation behavior. Increased SOC was primarily stored in the labile fraction with input from organic amendments. However, other less labile SOC fractions showed no further increase with greater C inputs exhibiting C saturation.Conclusions
While the paddy soil holds a high potential for SOC sequestration, stable C fractions saturate with increasing C inputs, and thus, additional C inputs mainly accumulate in labile soil C pools. 相似文献12.
pH change, carbon and nitrogen mineralization in paddy soils as affected by Chinese milk vetch addition and soil water regime 总被引：1，自引：0，他引：1
Yunfeng Wang Xingmei Liu Clayton Butterly Caixian Tang Jianming Xu 《Journal of Soils and Sediments》2013,13(4):654-663
Purpose
The aim of the research was to explore the effect of Chinese milk vetch (CM vetch) addition and different water management practices on soil pH change, C and N mineralization in acid paddy soils.Materials and methods
Psammaquent and Plinthudult paddy soils amended with Chinese milk vetch at a rate of 12 g?kg?1 soil were incubated at 25 °C under three different water treatments (45 % field capacity, CW; alternating 1-week wetting and 2-week drying cycles, drying rewetting (DRW) and waterlogging (WL). Soil pH, dissolved organic carbon, dissolved organic nitrogen (DON), CO2 escaped, microbial biomass carbon, ammonium (NH4 +) and nitrate (NO3 ?) during the incubation period were dynamically determined.Results and discussion
The addition of CM vetch increased soil microbial biomass concentrations in all treatments. The CM vetch addition also enhanced dissolved organic N concentrations in all treatments. The NO3–N concentrations were lower than NH4–N concentrations in DRW and WL. The pH increase after CM vetch addition was 0.2 units greater during WL than DRW, and greater in the low pH Plinthudult (4.59) than higher pH Paleudalfs (6.11) soil. Nitrogen mineralization was higher in the DRW than WL treatment, and frequent DRW cycles favored N mineralization in the Plinthudult soil.Conclusions
The addition of CM vetch increased soil pH, both under waterlogging and alternating wet–dry conditions. Waterlogging decreased C mineralization in both soils amended with CM vetch. Nitrogen mineralization increased in the soils subjected to DRW, which was associated with the higher DON concentrations in DRW than in WL in the acid soil. Frequent drying–wetting cycles increase N mineralization in acid paddy soils. 相似文献13.
Qingfeng Meng Jingsong Yang Rongjiang Yao Guangming Liu 《Journal of Soils and Sediments》2013,13(4):664-676
Purpose
The impacts of different land use practices on soil quality were assessed by measuring soil attributes and using factor analysis in coastal tidal lands. The study provided relevant references for coastal exploitation, land management and related researches in other countries and regions.Materials and methods
Measured soil attributes include physical indicators [bulk density (ρ b), total porosity (? t) and water-holding capacity (WHC)], chemical indicators [pH, electrical conductivity (EC), total nitrogen (TN), soil organic matter (SOM), available N, available P and available K] and biological indicators (urease activity, catalase activity and phosphatase activity), and 60 soil samples were collected within five land use types [(1) intertidal soils, (2) reclaimed tidal flat soils, (3) farmland soils, (4) suburban vegetable soils, (5) industrial area soils) in Jianggang village of Dongtai county, Jiangsu province of China.Results and discussion
The results from the investigation indicated that selected soil properties reduced to three factors for 0–20-cm soil depth; “Soil fertility status” (factor 1), “Soil physical status” (factor 2) and “Soil salinity status” (factor 3). For the first factor, the measured soil attributes with higher loadings were TN and SOM, which represented soil fertility feature, and for the second and third factors, the measured soil attributes with higher loadings were ρ b and available K as well as EC, which reflected soil physical properties and soil salinity feature, respectively.Conclusions
Changes in different land use types due to plants (corn, wheat and green vegetable) and application of fertilizers were characterized by promoted soil quality, including improvements in chemical properties (increasing SOM concentration, TN and nutrient available to plants; decreasing EC), improvements in soil physical properties (decreasing ρ b; increasing ? t and WHC) and enhancements in soil enzyme activities. Judging from the soil quality indices, the soil quality was affected by different land use practices and decreased in sequence of suburban vegetable soils, farmland soils, industrial area soils, reclaimed tidal flat soils and intertidal soils in the study area. 相似文献14.
Guixue Song Etelvino H. Novotny Karl G. Richards Michael H. B. Hayes 《Journal of Soils and Sediments》2018,18(11):3197-3214
Purpose
Dissolved organic matter (DOM), a heterogeneous mixture of low concentrations of organic matter draining from soils, plays a significant role in soil C cycling and in nutrient and pollutant transport. DOM from undisturbed soil profiles has rarely been studied. Hydrophobic acids (Ho) and hydrophilic acids (Hi), the major components of DOM, were recovered, using XAD-8 and XAD-4 resins in series, from waters draining in winter and in spring periods from well-drained and poorly drained Irish grassland soil profiles in lysimeters.Materials and methods
Waters were collected from 45 soil undisturbed lysimeters at the Teagasc Research Centre, Johnstown Castle, Wexford, Ireland. Four Irish representative soils had been collected as undisturbed 1.0-m-deep monoliths, transported to the experiment site and arranged randomly in an experimental facility. Water collections were carried out in winter and spring periods. The DOM was isolated and fractionated using an XAD-8 and XAD-4 resins in-tandem procedure, and hydrophobic acids (Ho) and hydrophilic acids (Hi) were isolated.Results and discussion
The amounts of DOM recovered in the winter period were much greater than those in the spring period, and the soil types had only minor influences on the DOM concentrations recovered. The Ho and Hi fraction contents ranged from 62 to 90 and 10 to 28%, respectively, of the total DOM content extracted. The Hi acids were most enriched in 13C, and considered to reflect greater microbial inputs. The neutral sugar (NS) contents for the Ho and Hi fractions were in the range of 15 to 52 μg mg?1, with the Hi fraction most enriched. The amino acids (AAs) for the Ho and Hi fractions varied from 0.6 to 2.4%, and the total AAs and NS of the Ho acids were well correlated. The DOM fractions from the drainage waters contained much less AAs and NS than the corresponding fractions in the parent soils. The solid- and liquid-state NMR data indicated organic structures with low aromaticity, significant amounts of carbohydrate and with lesser amounts of peptide structures, and with long-chain methylene (CH2)n and methine (-CH-) groups.Conclusions
The application of a variety of wet chemistry and of spectroscopy procedures has given a more in-depth awareness of the compositions of the DOM in the drainage waters from four different soils in 1.0-m-deep lysimeter arrangements. Based on wet chemistry analyses, and FTIR and liquid- and solid-state NMR spectrometry, it is clear that there are some differences between the compositions of the DOM fractions recovered. Alkyl functionalities dominated the structures. These included significant amounts or O-alkyl (predominantly carbohydrate), and with lesser (and variable amounts in the different fractions) aromatic structures (to which aromatic amino acid components were considered to be significant contributors), and with no evidence for lignin-derived structures The results suggest that, during residence in the soil solution, microbiological processes transform the SOM components released into products that are greatly different from their materials of origin in the SOM.15.
Dechao Duan Meng Wang Mingge Yu Dongyan Long Naveed Ullah Tingting Liu Jiyan Shi Yingxu Chen 《Journal of Soils and Sediments》2014,14(2):394-406
Purpose
Soil organic matter (SOM) plays a vital role in controlling metal bioavailability. However, the relationship between SOM and its fractions, including water-soluble substances (WSS), fulvic acid (FA), humic acid (HA), and soil microbial biomass (SMB), to metal bioavailability in plants has not been thoroughly investigated. This study examined the compositional change of SOM after tea polyphenols (TPs) were added to the soil and its correlation with Pb bioavailability.Materials and methods
Ultisol samples were collected from Fuyang, spiked with two levels (0 and 300 mg kg?1 DW) of Pb, and aged for 30 days. Four uniform seedlings were transplanted to each plastic pot, which were filled with 3 kg of air-dried soil. After successful transplantation, three levels (0, 300, and 600 mg kg?1 DW) of TPs were amended as irrigation solution for the pots. The Pb concentrations in different tissues of the tea plants were determined after 6 months. SOM, WSS, FA, HA, and SMB were extracted and quantified using a Multi N/C Total Organic Carbon Analyser.Results and discussion
Adding TPs to Pb-polluted soils alleviated Pb toxicity to microorganisms and increased SMB and the rhizosphere effect. The rhizosphere SOM was lower than bulk SOM in Pb-unspiked soils, while the opposite results were observed in Pb-spiked soils. A similar inconsistency for HA in the rhizosphere and bulk soil between Pb-unspiked and Pb-spiked soils might explain the difference in SOM. FA increased with the addition of TPs in both the rhizosphere and bulk soils, which might be the result of TP transformation. Positive correlations are present between the compositions of rhizosphere SOM and Pb in different tissues of the tea plant. SMB correlated negatively with Pb in young leaves and stems. Compared to rhizosphere soil, SOM components in bulk soil were less strongly correlated with Pb in tea plants.Conclusions
Addition of TPs to soil changes the components of SOM and Pb bioavailability. SOM and its fractions, including WSS, FA, HA, and SMB, show a close relationship to Pb in different tissues of the tea plants. 相似文献16.
The inhibiting effect of nitrate fertilisation on methane uptake of a temperate forest soil is influenced by labile carbon 总被引：1，自引：0，他引：1
Ann-Catrin Fender Birgit Pfeiffer Dirk Gansert Christoph Leuschner Rolf Daniel Hermann F. Jungkunst 《Biology and Fertility of Soils》2012,48(6):621-631
Upland soils are the most important terrestrial sink for the greenhouse gas CH4. The oxidation of CH4 is highly influenced by reactive N which is increasingly added to many ecosystems by atmospheric deposition and thereby also alters the labile C pool in the soils. The interacting effects of soil N availability and the labile C pool on CH4 oxidation are not well understood. We conducted a laboratory experiment with soil columns consisting of homogenised topsoil material from a temperate broad-leaved forest to study the net CH4 flux under the combined or isolated addition of NO 3 ? and glucose as a labile C source. Addition of NO 3 ? and glucose reduced the net CH4 uptake of the soil by 86% and 83%, respectively. The combined addition of both agents led to a nearly complete inhibition of CH4 uptake (reduction by 99.4%). Our study demonstrates a close link between the availability of C and N and the rate of CH4 oxidation in temperate forest soils. Continued deposition of NO 3 ? has the potential to reduce the sink strength of temperate forest soils for CH4. 相似文献
17.
Purpose
Application of olive mill wastewater (OMW) to soil may cause positive or negative effects. The present study aims at a better understanding of the fate of organic matter brought into soil by OMW application under different environmental conditions.Materials and methods
Single OMW application to soil was conducted in spring, dry summer, summer with irrigation, and in winter. Two days and 18–24 months after the application, soil samples from two depths were analyzed for thermal soil organic matter (SOM) properties, total organic carbon, water-extractable dissolved soil organic carbon, and its specific ultraviolet absorbance at 254 nm.Results and discussion
After winter and irrigated summer treatments, OMW was largely leached from the upper horizon within 2 days. Application in spring and summer dry initially increased the thermolabile fraction and the calorific value of SOM, however, in a different degree due to different transport, transformation, and immobilization mechanisms. At the long term, SOM content was still elevated after summer dry treatment. The reduction of the thermostable fraction in spring treatment indicates a priming effect of the labile OMW constituents.Conclusions
Application in winter or with irrigation cannot be recommended for the investigated site. Under hot and dry conditions, SOM content increased most persistently due to stronger mineral-organic interactions. Favorable conditions for biodegradation during OMW application in spring reduced the effects on SOM quantity in the long term. However, a possible priming effect and the persistence of changes in thermal properties need to be further investigated for repeated applications.18.
Purpose
Soil labile carbon (C) and nitrogen (N) pools are considered to be sensitive indicators of changes in soil C and N pools. In this study, we examined possible factors affecting spatial and seasonal variations in soil labile C and N pools in the riparian zones in Southeast Queensland, Australia.Materials and methods
Soil and sediment samples were collected from two sites in the riparian areas. The spatial and seasonal variabilities of soil moisture, hot-water extractable organic C and total N (HWEOC and HWETN), microbial biomass C and N (MBC and MBN), and the relationships among them were examined.Results and discussion
Soil labile C and N pools decreased along the transects in both soil depths of the two soil types, with the peak or bottom of values detected between upland slope and the riparian zone. Other factors rather than soil moisture were more important in regulating seasonal changes of soil HWEOC and HWETN except the dry-rewetting influence in November 2013. Soil moisture played a significant role in the seasonal variations of MBC and MBN. Soil labile C (HWEOC and MBC) and N (HWETN and MBN) pools at Site 1 (S1; heavy texture), which were significantly higher than those at Site 2 (S2; light texture).Conclusions
Soil moisture would be an important driving factor for the spatial and seasonal distributions of soil labile C and N pools. Our study highlighted the importance of riparian zones as the hot spot of soil C and N dynamics, especially at the onset of rewetting dry soil in subtropical Australia.19.
Soil carbon dioxide emission from intensively cultivated black soil in Northeast China: nitrogen fertilization effect 总被引：1，自引：0，他引：1
Kang Ni Weixin Ding Zucong Cai Yufeng Wang Xilin Zhang Baoku Zhou 《Journal of Soils and Sediments》2012,12(7):1007-1018
Purpose
The aim of this study was to understand the effect of nitrogen fertilization on soil respiration and native soil organic carbon (SOC) decomposition and to identify the key factor affecting soil respiration in a cultivated black soil.Materials and methods
A field experiment was conducted at the Harbin State Key Agroecological Experimental Station, China. The study consisted of four treatments: unplanted and N-unfertilized soil (U0), unplanted soil treated with 225?kg?N?ha?1 (UN), maize planted and N-unfertilized soil (P0), and planted soil fertilized with 225?kg?N?ha?1 (PN). Soil CO2 and N2O fluxes were measured using the static closed chamber method.Results and discussion
Cumulative CO2 emissions during the maize growing season with the U0, UN, P0, and PN treatments were 1.29, 1.04, 2.30 and 2.27?Mg?C?ha?1, respectively, indicating that N fertilization significantly reduced the decomposition of native SOC. However, no marked effect on soil respiration in planted soil was observed because the increase of rhizosphere respiration caused by N addition was counteracted by the reduction of native SOC decomposition. Soil CO2 fluxes were significantly affected by soil temperature but not by soil moisture. The temperature sensitivity (Q 10) of soil respiration was 2.16?C2.47 for unplanted soil but increased to 3.16?C3.44 in planted soil. N addition reduced the Q 10 of native SOC decomposition possibly due to low labile organic C but increased the Q 10 of soil respiration due to the stimulation of maize growth. The estimated annual CO2 emission in N-fertilized soil was 1.28?Mg?C?ha?1 and was replenished by the residual stubble, roots, and exudates. In contrast, the lost C (1.53?Mg?C?ha?1) in N-unfertilized soil was not completely supplemented by maize residues, resulting in a reduction of SOC. Although N fertilization significantly increased N2O emissions, the global warming potential of N2O and CO2 emissions in N-fertilized soil was significantly lower than in N-unfertilized soil.Conclusions
The stimulatory or inhibitory effect of N fertilization on soil respiration and basal respiration may depend on labile organic C concentration in soil. The inhibitory effect of N fertilization on native SOC decomposition was mainly associated with low labile organic C in tested black soil. N application could reduce the global warming potential of CO2 and N2O emissions in black soil. 相似文献20.
Jolanta Kwiatkowska-Malina 《Journal of Soils and Sediments》2018,18(8):2801-2812