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1.
E. A. Mikhailova R. Y. Stiglitz C. J. Post M. A. Schlautman J. L. Sharp P. D. Gerard 《Eurasian Soil Science》2017,50(12):1414-1419
Color sensor technologies offer opportunities for affordable and rapid assessment of soil organic carbon (SOC) and total nitrogen (TN) in the field, but the applicability of these technologies may vary by soil type. The objective of this study was to use an inexpensive color sensor to develop SOC and TN prediction models for the Russian Chernozem (Haplic Chernozem) in the Kursk region of Russia. Twenty-one dried soil samples were analyzed using a Nix Pro? color sensor that is controlled through a mobile application and Bluetooth to collect CIEL*a*b* (darkness to lightness, green to red, and blue to yellow) color data. Eleven samples were randomly selected to be used to construct prediction models and the remaining ten samples were set aside for cross validation. The root mean squared error (RMSE) was calculated to determine each model’s prediction error. The data from the eleven soil samples were used to develop the natural log of SOC (lnSOC) and TN (lnTN) prediction models using depth, L*, a*, and b* for each sample as predictor variables in regression analyses. Resulting residual plots, root mean square errors (RMSE), mean squared prediction error (MSPE) and coefficients of determination (R2, adjusted R2) were used to assess model fit for each of the SOC and total N prediction models. Final models were fit using all soil samples, which included depth and color variables, for lnSOC (R2 = 0.987, Adj. R2 = 0.981, RMSE = 0.003, p-value < 0.001, MSPE = 0.182) and lnTN (R2 = 0.980 Adj. R2 = 0.972, RMSE = 0.004, p-value < 0.001, MSPE = 0.001). Additionally, final models were fit for all soil samples, which included only color variables, for lnSOC (R2 = 0.959 Adj. R2 = 0.949, RMSE = 0.007, p-value < 0.001, MSPE = 0.536) and lnTN (R2 = 0.912 Adj. R2 = 0.890, RMSE = 0.015, p-value < 0.001, MSPE = 0.001). The results suggest that soil color may be used for rapid assessment of SOC and TN in these agriculturally important soils. 相似文献
2.
Pedotransfer functions (PTFs) are widely used for hydrological calculations based on the known basic properties of soils and sediments. The choice of predictors and the mathematical calculus are of particular importance for the accuracy of calculations. The aim of this study is to compare PTFs with the use of the nonlinear regression (NLR) and support vector machine (SVM) methods, as well as to choose predictor properties for estimating saturated hydraulic conductivity (Ks). Ks was determined in direct laboratory experiments on monoliths of agrosoddy-podzolic soil (Umbric Albeluvisol Abruptic, WRB, 2006) and calculated using PTFs based on the NLR and SVM methods. Six classes of predictor properties were tested for the calculated prognosis: Ks-1 (predictors: the sand, silt, and clay contents); Ks-2 (sand, silt, clay, and soil density); Ks-3 (sand, silt, clay, soil organic matter); Ks-4 (sand, silt, clay, soil density, organic matter); Ks-5 (clay, soil density, organic matter); and Ks-6 (sand, clay, soil density, organic matter). The efficiency of PTFs was determined by comparison with experimental values using the root mean square error (RMSE) and determination coefficient (R2). The results showed that the RMSE for SVM is smaller than the RMSE for NLR in predicting Ks for all classes of PTFs. The SVM method has advantages over the NLR method in terms of simplicity and range of application for predicting Ks using PTFs. 相似文献
3.
Yu. V. Egorov I. I. Sudnitsyn A. V. Kirichenko 《Moscow University Soil Science Bulletin》2016,71(4-5):165-170
The contamination of heavy loamy chernozem by iron, sodium, magnesium, calcium, and hydrogen chlorides (2% of soil mass) decreases soil moisture content (W, percent of soil mass) in the interval of the soil moisture pressure (Р) from 0.0 to–0.6 atm, which indicate soil degradation. In a range of P from–0.2 to–0.6 atm, there is a close correlation between the logarithm of Р module (log|P|) and W and, therefore, a regression relationship log|P W | = |P 0|–kW, where |P 0| and k are empirically determined parameters. This relationship is similar to the Landau–Deryagin law. The parameters |P 0| and k are also in a close correlation, which is described by the regression equation |P 0| = 29.3k–0.557. At chernozem contamination by chlorides, the |P 0| and k parameters become smaller, and so they may be used for the evaluation of degradation of chloride-contaminated soils. 相似文献
4.
L. I. Belykh I. A. Ryabchikova V. A. Seryshev E. E. Penzina S. S. Timofeeva 《Eurasian Soil Science》2007,40(2):176-186
New methodological approaches and an algorithm for the quantitative assessment of accumulating a substance by a plant (C p ) with due regard for its concentration in the soil (C n ) are proposed. The first approach is the approximation of concentration curves by the functions C p = f(C n ) and their parameters. The second one is the standardization of the coefficients of biological sorption (K b ) of a substance upon its stable concentration in the soil using the function K b = f(C n ). As compared to the variation-statistical values of the mean and extreme concentrations, or the coefficients K b , the proposed parameters are characterized by a higher accuracy and sensitivity. They may be successfully used for quantitative studies of the mechanism and the intensity of the absorption of substances by plants, for the prediction of the accumulation of substances in the trophic chain, and the assessment of soil self-purification (detoxification) and comparative ratings. 相似文献
5.
Hysteresis of the soil water retention curve (SWRC), manifested as a difference between equilibrium curves of soil wetting and drying (hysteresis loop), is a phenomenon specific to soil hydrology, which is of practical importance for calculating irrigation norms. We have attempted to derive a model of the wetting curve from the drying curve. Modeling was based on parameters proposed by van Genuchten [6] and certain soil physical characteristics. SWRC hysteresis characteristics were obtained experimentally using capillarimetric measurements for wetting and drying curves at soil water pressures ranging from 0 to –800 cmH2O. Two models, М-1 and М-2, based on the hypothesis of dissimilarity of parameters α for wetting (αw) and drying (αd) and the constancy of other parameters of the van Genuchten SWRC approximation for both curves of the hysteresis loop, have been developed for wetting curve assessment based on the drying curve. The M-1 error (RMSE = 0.05 cm–1) was less than that of M-2 (RMSE = 0.06 cm–1), which used clay content and soil density as predictors, as well as that of the well-known model proposed by Kool and Parker [11]. This approach to derive the wetting curve from the drying curve for a presumed correlation between the values of one parameter and equal values of the other parameters, can be used to predict an estimate of the SWRC hysteresis for a specific soil. 相似文献
6.
The saturated hydraulic conductivity (Ks) of the soil is one of the main soil physical properties. Indirect estimation of this parameter using pedo-transfer functions (PTFs) has received considerable attention. The Purpose of this study was to improve the estimation of Ks using fractal parameters of particle and micro-aggregate size distributions in smectitic soils. In this study 260 disturbed and undisturbed soil samples were collected from Guilan province, the north of Iran. The fractal model of Bird and Perrier was used to compute the fractal parameters of particle and micro-aggregate size distributions. The PTFs were developed by artificial neural networks (ANNs) ensemble to estimate Ks by using available soil data and fractal parameters. There were found significant correlations between Ks and fractal parameters of particles and microaggregates. Estimation of Ks was improved significantly by using fractal parameters of soil micro-aggregates as predictors. But using geometric mean and geometric standard deviation of particles diameter did not improve Ks estimations significantly. Using fractal parameters of particles and micro-aggregates simultaneously, had the most effect in the estimation of Ks. Generally, fractal parameters can be successfully used as input parameters to improve the estimation of Ks in the PTFs in smectitic soils. As a result, ANNs ensemble successfully correlated the fractal parameters of particles and micro-aggregates to Ks. 相似文献
7.
Diying Xiang Gang Zhang Ruijuan Gong Bao Di Yaran Tian 《Water, air, and soil pollution》2018,229(8):279
The use of plants for ecological remediation is an important method of controlling heavy metals in polluted land. Cotinus coggygria is a landscape plant that is used extensively in landscaping and afforestation. In this study, the cadmium tolerance level of C. coggygria was evaluated using electrical impedance spectroscopy (EIS) to lay a theoretical foundation for broad applications of this species in Cd-polluted areas and provide theoretical support to broaden the application range of the EIS technique. Two-year-old potted seedlings of C. coggygria were placed in a greenhouse to analyse the changes in the growth, water content and EIS parameters of the roots following treatment with different Cd concentrations (50, 100, 200, 500, 1000 and 1500 mg kg?1), and soil without added Cd was used as the control. The roots grew well following Cd treatments of 50 and 100 mg kg?1. The Cd contents increased with the increase in Cd concentration in the soil. However, the lowest root Cd content was found at 4 months of treatment. The extracellular resistance re and the intracellular resistance ri increased first overall and then decreased with the increasing Cd concentration, and both parameters increased with a longer treatment duration. The water content had a significant negative correlation with the Cd content (P?<?0.01) and the re (P?<?0.05). C. coggygria could tolerate a soil Cd concentration of 100 mg kg?1. There was a turning point in the growth, water content and EIS parameters of the C. coggygria roots when the soil Cd concentration reached 200 mg kg?1. The root water content and re could reflect the level of Cd tolerance in C. coggygria. 相似文献
8.
Mónica Claudia Savini Ruth Miriam Loewy Viviana Estela Nicotra María Eugenia Parolo 《Water, air, and soil pollution》2017,228(1):36
It is generally assumed that the sorption of a nonionic pesticide on soil depends mainly on the content of soil organic matter (SOM); however, there are other factors that can contribute to this process. The possible causes of variation in the carbon-normalized partition coefficient (K OC) for chlorpyrifos (CPF) for a diverse set of ten soils have been investigated. On the one hand, the analysis of the chemical composition of the SOM was analyzed, and on the other hand, the likely interactions between the organic matter and the mineral phase were assessed. Sorption experiments of CPF were performed on whole soil, on soils treated with 2% hydrofluoric acid (HF), and onto calcined soil at 550 °C. Organic matter chemistry of soil was determined by 13C CP/MAS NMR spectroscopy; K OC values were positively correlated with aryl C relative proportion and negatively correlated with alkyl C and O-aryl C proportions and prediction equation of K OC was found (R 2?=?0.82, p?<?0.001). To evaluate possible organo-mineral interactions, a mathematical model was proposed which calculates the concentration of CPF at equilibrium (C cal) considering adsorption coefficients for the organic (K DHF) and inorganic (K D550 °C) soil constituents, separately. The comparison between C cal and the equilibrium concentration obtained from experimental data (C exp) onto whole soil allowed us to confirm that interactions between the OM and clay affect the adsorption of CPF in whole soil. Such findings should be taken into account in the development of predictive models for the evaluation of the fate and transport of this pesticide in soil. 相似文献
9.
Peng Su Jun Lou Philip C. Brookes Yu Luo Yan He Jianming Xu 《Journal of Soils and Sediments》2017,17(3):674-684
Purpose
This work investigated changes in priming effects and the taxonomy of soil microbial communities after being amended with plant feedstock and its corresponding biochar.Materials and methods
A soil incubation was conducted for 180 days to monitor the mineralization and evolution of soil-primed C after addition of maize and its biochar pyrolysed at 450 °C. Responses of individual microbial taxa were identified and compared using the next-generation sequencing method.Results and discussion
Cumulative CO2 showed similar trends but different magnitudes in soil supplied with feedstock and its biochar. Feedstock addition resulted in a positive priming effect of 1999 mg C kg?1 soil (+253.7 %) while biochar gave negative primed C of ?872.1 mg C kg?1 soil (?254.3 %). Linear relationships between mineralized material and mineralized soil C were detected. Most priming occurred in the first 15 days, indicating co-metabolism. Differences in priming may be explained by differences in properties of plant material, especially the water-extractable organic C. Predominant phyla were affiliated to Acidobacteria, Actinobacteria, Chloroflexi, Gemmatimonadetes, Firmicutes, Planctomycetes, Proteobacteria, Verrucomicrobia, Ascomycota, Basidiomycota, Blastocladiomycota, Chytridiomycota, Zygomycota, Euryarchaeota, and Thaumarchaeota during decomposition. Cluster analysis resulted in separate phylogenetic grouping of feedstock and biochar. Bacteria (Acidobacteria, Firmicutes, Gemmatimonadetes, Planctomycetes), fungi (Ascomycota), and archaea (Euryarchaeota) were closely correlated to primed soil C (R 2?=??0.98, ?0.99, 0.84, 0.81, 0.91, and 0.91, respectively).Conclusions
Quality of plant materials (especially labile C) shifted microbial community (specific microbial taxa) responses, resulting in a distinctive priming intensity, giving a better understanding of the functional role of soil microbial community as an important driver of priming effect.10.
Purpose
Forest soil respiration is an important component of global carbon budgets, but its spatial variation is inadequately understood. This research aimed to measure soil respiration (R s), soil water content (M s-5), soil temperature (T), and carbon dioxide (M co2) in a coastal protection forest (CPF), which is one kind of man-made forests designed for coastal protection primarily along the coast in China, to determine the relationships among them, and to analyze their spatial distributions in a small scale.Materials and methods
We measured R s, M s-5, T, and M co2 of 100 plots in an approximately flat grid (totally 4 hm2) by LI-8100A in a Casuarina equisetifolia L. forest on a state-owned forest farm of 326 hm2 in SE China. Traditional statistics and geo-statistics including semivariance, Moran’s I index, and fractal dimension were used to analyze data.Results and discussion
Key findings were that (1) the spatial mean of R s, M s-5, T, and M co2 were 1.194 μmol m?2 s?1, 11.387 mmol mol?1, 14.153 °C, and 407.716 ppm, respectively, in the forest; (2) the relationship between soil respiration and the other three factors was weak, while M s-5, T, and M co2 have strong relationships with each other; and (3) the four factors, especially soil respiration, had strong autocorrelation within given limits and showed great heterogeneity with 95 % confidence intervals around the means in the study area, all of which can provide important value for the study of carbon cycling and for the sustainable management of coastal protection forests.Conclusions
According to geo-statistical analysis and field investigations, soil respiration in the coastal forest is less than in some broad-leaf forests but higher than in some conifers. Strong heterogeneity and autocorrelation are clear; however, its relation with other three factors is weak. CPF is a considerable potential forest for carbon conservation if it is well managed.11.
An investigation of the effect of aquic conditions on Fe-oxides distribution and magnetic susceptibility (χlf) was conducted on selected soils from Southern Iran. Seven pairs of adjacent soil pedons with different soil moisture regimes (aquic and non-aquic), were selected. The average concentrations of poorly crystalline Fe (Feo) and total free Fe (Fed) in aquic soils were 0.2 and 0.07% respectively, and 0.45 and 0.9% in non-aquic soils, respectively. The ratio of Feo/Fed varied from 0.03 to 0.64. χlf ranged from 1.8 to 113 × 10?8 m3 kg?1 in the soil studied. The variation of χfd ranged from 0.0 to 9.65%. The χfd values observed in non-aquic soils were larger than in aquic soils (4.00% vs. 1.37%). Positive correlations were observed between χ and clay contents in both aquic and non-aquic soils; however, non-aquic soil samples showed a larger coefficient of determination. A positive correlation existed between χfd and χ in aquic and non-aquic soils. Higher values of χfd were observed at the soil surface of non-aquic soil samples than at deeper levels, suggesting a greater proportion of ultrafine grains. Of the soil properties that were assessed, clay, cation exchangeable capacity (CEC), Fed, Feo/Fed ratio, χlf and χfd contents, changed significantly in response to the aquic condition. 相似文献
12.
Tongbin?Zhu Cheng?Yang Jun?Wang Siman?Zeng Manqiang?Liu Jinling?Yang Bing?Bai Jianhua?Cao Xiaoyun?Chen
We conducted a microcosm experiment with soil being sterilized, reinoculated with native microbial community and subsequently manipulated the bacterivorous nematodes, including three treatments: without (CK) or with introducing one species of the two bacterivores characterized with different body size but similar c-p (colonizer-persister) value (Rhabditis intermedia and Protorhabditis oxyuroides, accounted for 6 and 59% of bacterivores in initially undisturbed soil, respectively). We monitored the N2O and CO2 emissions, soil properties, and especially quantified gross N transformation rates using 15N tracing technique after the 50 days incubation. No significant differences were observed on soil NH4 + and NO3 ? concentrations between the CK and two bacterivores, but this was not the case for gross N transformation rates. In comparison to CK, R. intermedia did not affect soil N transformation rates, while P. oxyuroides significantly increased the rates of mineralization of organic N to NH4 +, oxidation of NH4 + to NO3 ?, immobilization of NO3 ? to organic N and dissimilatory NO3 ? reduction to NH4 +. Furthermore, the mean residence time of NH4 + and NO3 ? pool was greatly lowered by P. oxyuroides, suggesting it stimulated soil N turnover. Such stimulatory effect was unrelated to the changes in abundance of bacteria and ammonia-oxidizing bacteria (AOB). In contrast to CK, only P. oxyuroides significantly promoted soil N2O and CO2 emissions. Noticeably, bacterivores increased the mineralization of recalcitrant organic N but decreased soil δ13C-TOC and δ15N-TN values, in particular for P. oxyuroides. Combining trait-based approach and isotope-based analysis showed high potential in moving forward to a mechanistic understanding of bacterivore-mediated N cycling. 相似文献
13.
The aim of this study was to investigate the burrowing activity of two earthworm species: the endogeic Drawida sinica and one undescribed Amynthas species incubated in Vertisol and Ultisol presenting different soil organic C content. Because of their contrasting feeding behaviours, we hypothesised that soil type would have a bigger influence on the burrowing activity of the endogeic than the anecic species. Repacked soil columns inoculated with earthworms for 30 days were scanned using X-ray tomography and the compiled images used to characterise the burrow systems. After scanning, the saturated hydraulic conductivity (K sat) was also measured. The Amynthas species burrows were less numerous (30 vs. 180), more vertically oriented (57 vs. 37°), more connected from the surface to the bottom of the columns (73 vs. 5 cm3) and had a higher global connectivity index (83 vs. 28%) than those of D. sinica. The K sat was threefold faster in columns incubated with Amynthas and was linked to the volume of percolating burrows (R 2 = 0.81). The soil type did not influence Amynthas burrow characteristics. In contrast, there were 30% more D. sinica burrows in the Vertisol than in the Ultisol while other burrow characteristics were not affected. This result suggests that these burrows were more refilled with casts leading to shorter and discontinuous burrows. The K sat was negatively related to the number of burrows (R 2 = 0.44) but was not statistically different between the Vertisol and the Ultisol, suggesting a constant impact of this species on the K sat. We found that a decrease in the amount of soil organic C by 50% had only a small influence on earthworm burrowing activity and no effect on the K sat. 相似文献
14.
Hongling?Qin Yafang?Tang Jianlin?Shen Cong?Wang Chunlan?Chen Jie?Yang Yi?Liu Xiangbi?Chen Yong?Li Haijun?Hou
Agricultural management significantly affects methane (CH4) and nitrous oxide (N2O) emissions from paddy fields. However, little is known about the underlying microbiological mechanism. Field experiment was conducted to investigate the effect of the water regime and straw incorporation on CH4 and N2O emissions and soil properties. Quantitative PCR was applied to measure the abundance of soil methanogens, methane-oxidising bacteria, nitrifiers, and denitrifiers according to DNA and mRNA expression levels of microbial genes, including mcrA, pmoA, amoA, and nirK/nirS/nosZ. Field trials showed that the CH4 and N2O flux rates were negatively correlated with each other, and N2O emissions were far lower than CH4 emissions. Drainage and straw incorporation affected functional gene abundance through altered soil environment. The present (DNA-level) gene abundances of amoA, nosZ, and mcrA were higher with straw incorporation than those without straw incorporation, and they were positively correlated with high concentrations of soil exchangeable NH4+ and dissolved organic carbon. The active (mRNA-level) gene abundance of mcrA was lower in the drainage treatment than in continuous flooding, which was negatively correlated with soil redox potential (Eh). The CH4 flux rate was significantly and positively correlated with active mcrA abundance but negatively correlated with Eh. The N2O flux rate was significantly and positively correlated with present and active nirS abundance and positively correlated with soil Eh. Thus, we demonstrated that active gene abundance, such as of mcrA for CH4 and nirS for N2O, reflects the contradictory relationship between CH4 and N2O emissions regulated by soil Eh in acidic paddy soils. 相似文献
15.
Peng Su Yong Liu Sifan Wang Zhongqi Yan Shan Wang Lian Zhu Jun Lou Fangbai Li 《Journal of Soils and Sediments》2018,18(9):2904-2913
Purpose
A rapid and alternative measurement of microbial biomass in acid red soils with and without substrate incorporation is proposed for soil quality evaluation.Materials and methods
Soil microbial biomass C (SMBC) and N (SMBN) in 24 typical red soil samples developed from two parent materials (granite and arenaceous shale) were measured using fumigation-extraction followed by dry combustion method in comparison with ultraviolet (UV) spectrophotometry (increase in absorbance at 280 nm, ΔUV280). The reliability of microbial biomass estimation by UV spectrophotometry was verified using six representative red soils amended with biochar (0, 1, 3 and 5%) and glucose (0, 100, 500 and 1000 mg kg?1) separately.Results and discussion
ΔUV280 was strongly correlated with SMBC and SMBN measured by dry combustion, regardless of biochar/glucose incorporation. Validated conversion equations from unamended soil data were dependent on confounding effects of organic C and particle size and can be described as follows: SMBC?=?27.08?×?ΔUV280 (R2?=?0.67, n?=?24) and SMBN?=?3.62?×?ΔUV280 (R2?=?0.69, n?=?24). Regression models for rapid estimation of microbial biomass in red soils from different parent materials had to be calibrated separately in case of amendments. In most cases, SMBC (R2 of 0.75–0.76 and root mean square error (RMSE) of 22.2–29.3 mg kg?1) and SMBN (R2 of 0.74–0.80 and RMSE of 2.60–14.2 mg kg?1) can be predicted from ΔUV280 in biochar/glucose-amended soils using these equations. The slope of the regression of SMBC against ΔUV280 shifted in biochar-amended granite soils, mainly due to uncoordinated changes of SMBC in response to the difference in parent material-induced nutrient availability, while shifts of SMBC (or SMBN) against ΔUV280 in glucose-amended arenaceous shale soils were attributed to particle size distribution.Conclusions
Soil microbial biomass (SMBC and SMBN) in red soils can be rapidly predicted by fumigation-extraction with UV spectrophotometry detection and corresponding correction of calibration curves, depending on soil nutrient availability, particle size distribution and organic C levels.16.
G. M. Zenova A. A. Gryadunova E. A. Doroshenko A. A. Likhacheva I. I. Sudnitsyn T. N. Pochatkova D. G. Zvyagintsev 《Eurasian Soil Science》2007,40(5):560-564
It was found that the actinomycetal complex of a cultivated low-moor peat soil is characterized by a high population density and diversity of actinomycetes; representatives of eleven genera were isolated from this soil: Streptomyces, Micromonospora, Actinomadura, Saccharopolyspora, Microbispora, Microtetraspora, Streptosporangium, Nocardioides, Saccharomonospora, Kibdelosporangium, and Thermomonospora. Some genera were isolated from the soil under all the studied levels of soil moisture. The so-called rare (rarely occurring) genera (Saccharomonospora, Kibdelosporangium, and Thermomonospora) were isolated upon the low level of soil moisture, which ensured an absence of competition from the more abundant actinomycetes. Spores of all the studied actinomycetes could germinate under the low moisture level (a w = 0.67). The level of moisture a w = 0.98 was found to be optimal for the development of the actinomycetes. The complete cycle of the development of all the actinomycetes up to spore formation occurring was only observed under the high moisture level (a w = 0.98). 相似文献
17.
Jin-Ling Yang Gan-Lin Zhang Fei Yang Ren-Min Yang Chen Yi De-Cheng Li Yu-Guo Zhao Feng Liu 《Journal of Soils and Sediments》2016,16(10):2408-2418
Purpose
Surface crusts are important features in arid desert areas and are critical to hydrological processes and ecosystem development. This paper aims to understand the effects of crusts on water movement in the soil and the factors that affect this and to provide the soil parameters for estimation of saturated hydraulic conductivity (K s) in ecohydrological models.Materials and methods
The study area was located in the middle and lower reaches of the Heihe River Basin, an arid desert area in Northwest China. There were three crust types in this region: physical soil crusts (PSCs, formed by water drop and erosion), biological soil crusts (BSCs, formed by microorganisms, moss, algae, lichen, and soil materials), and salt soil crusts (SSCs, formed by soluble salts). The infiltration rates of different soil and crust types and scalped soils were determined in situ in the field conditions using a disc infiltrometer with three repetitions. Crusts and soils were collected, and their properties were determined in the laboratory.Results and discussion
The K s of crust were significantly lower than that of scalped soils with a decrease of 13–70 %. The K s of crusts were related to the type of crust and the properties of soil beneath the crusts. In this region, the soil textures are similar throughout, due to ubiquitous loess sedimentation, so textural differences had no significant effect on K s. Soil organic matter (SOM) played a weak negative role on K s because most crusts had higher SOM than the underlying soil. However, both crust thickness and electrical conductivity (EC, an index of salt concentration) showed significantly negative exponential relationship with K s. Therefore, the SSC with high EC and thick crust have the lowest K s among all crust types. Because soil development is related to salt accumulation, structure, and crust formation, the K s follows the order of Solonchaks < Cambisols < Regosols, from lowest to highest.Conclusions
Crusts have different characteristics compared with original soils and are the limiting layer of water infiltration in these arid soils. Therefore, the characteristics of crust must be considered in ecohydrological models. The main apparent controlling parameters of water infiltration rate in this area are crust thickness and EC.18.
Vincenzo Bagarello Vito Ferro Vincenzo Pampalone Paolo Porto Francesca Todisco Lorenzo Vergni 《Journal of Soils and Sediments》2018,18(12):3365-3377
Purpose
The USLE-MM estimates event normalized plot soil loss, Ae,N, by an erosivity term given by the runoff coefficient, QR, times the single-storm erosion index, EI30, raised to an exponent b1?>?1. This modeling scheme is based on an expected power relationship, with an exponent greater than one, between event sediment concentration, Ce, and the EI30/Pe (Pe = rainfall depth) term. In this investigation, carried out at the three experimental sites of Bagnara, Masse, and Sparacia, in Italy; the soundness of the USLE-MM scheme was tested.Materials and methods
A total of 1192 (Ae,N, QREI30) data pairs were used to parameterize the model both locally and considering all sites simultaneously. The performances of the fitted models were established by considering all erosive events and also by distinguishing between events of different severity.Results and discussion
The b1 exponent varied widely among the three sites (1.05–1.44) but using a common exponent (1.18) for these sites was possible. The Ae,N prediction accuracy increased in the passage from the smallest erosion events (Ae,N?≤?1 Mg ha?1, median error =?3.35) to the largest ones (Ae,N?>?10 Mg ha?1, median error =?1.72). The QREI30 term was found to be usable to predict both Ae,N and the expected maximum uncertainty of this prediction. Soil erodibility was found to be mainly controlled by the largest erosion events.Conclusions
Development of a single USLE-MM model appears possible. Sampling other sites is advisable to develop a single USLE-MM model for a general use.19.
Yaling Zhang Hong Chen Shahla Hosseini Bai Carl Menke Manyun Zhang Zhihong Xu 《Journal of Soils and Sediments》2017,17(10):2400-2409
Purpose
This study aimed to assess the effects of biochar on improving nitrogen (N) pools in mine spoil and examine the effects of elevated CO2 on soil carbon (C) storage.Materials and methods
The experiment consisted of three plant species (Austrostipa ramossissima, Dichelachne micrantha, and Lomandra longifolia) planted in the N-poor mine spoil with application of biochar produced at three temperatures (650, 750, and 850 °C) under both ambient (400 μL L?1) and elevated (700 μL L?1) CO2. We assessed mine spoil total C and N concentrations and stable C and N isotope compositions (δ13C and δ15N), as well as hot water extractable organic C (HWEOC) and total N (HWETN) concentrations.Results and discussion
Soil total N significantly increased following biochar application across all species. Elevated CO2 induced soil C loss for A. ramossissima and D. micrantha without biochar application and D. micrantha with the application of biochar produced at 750 °C. In contrast, elevated CO2 exhibited no significant effect on soil total C for A. littoralis, D. micrantha, or L. longifolia under any other biochar treatments.Conclusions
Biochar application is a promising means to improve N retention and thus, reduce environmentally harmful N fluxes in mine spoil. However, elevated CO2 exhibited no significant effects on increasing soil total C, which indicated that mine spoil has limited potential to store rising atmospheric CO2.20.
Anna M. Stefanowicz Marta L. Majewska Małgorzata Stanek Marcin Nobis Szymon Zubek 《Journal of Soils and Sediments》2018,18(4):1409-1423