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soil Organic Carbon Pools in Particle-Size Fractions as Affected by Slope Gradient and Land Use Change in Hilly Regions,Western Iran

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Journal of Mountain science 2012年第1期9卷 87-95页

作者： Parisa Mokhtari KARCHEGANI Shamsollah AYOUBI Mohammad Reza MOSADDEGHI Naser HONARJOO Department of soil science College of AgricultureIslamic Azad UniversityKhorasgan BranchIsfahanIran departmnet of soil science College of AgricultureIsfahan University of Technology84156-83111IsfahanIran.

This study was conducted to explore the effects of topography and land use changes on particulate organic carbon(POC),particulate total nitrogen(PTN),organic carbon(OC) and total nitrogen(TN) associated with different size primary particle fractions in hilly regions of western *** popular land uses in the selected site including natural forest(NF),disturbed forest(DF) and cultivated land(CL) and three slope gradients(0-10 %,S1,10-30 %,S2,and 30-50%,S3) were employed as the basis of soil sampling.A total of 99 soil samples were taken from the 0-10 cm surface layer in the whole studied hilly region *** results showed that the POC in the forest land use in all slope gradients was considerably more than the deforested and cultivated lands and the highest value was observed at NF-S1 treatment with 9.13%.The values of PTN were significantly higher in the forest land use and in the down slopes(0.5%) than in the deforested and cultivated counterparts and steep slopes(0.09%) except for the CL land *** C:N ratios in POC fraction were around 17-18 in the forest land and around 23 in the cultivated *** forest land,the silt-associated OC was highest among the primary *** enrichment factor of SOC,EC,was the highest for *** the primary particles,EC of both primary fractions of silt and clay showed following trend for selected land uses and slope gradients:CL> DF> NF and S3 > S2> *** gradient of landscape significantly affected the OC and TN contents associated with the silt and clay particles,whereas higher OC and TN contents were observed in lower positions and the lowest value was measured in the steep ***,the results showed that native forest land improves soil organic carbon storage and can reduce the carbon emission and soil erosion especially in the mountainous regions with high rainfall in west of Iran.

关键词： Land use change soil organic carbon Slope gradient Physical fractionation Particulate organic carbon

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Interrelationship between soil depth and soil properties of Pieniny National Park forest(Poland)

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Journal of Mountain science 2019年第7期16卷 1534-1545页

作者： Justyna SOKO?OWSKA Agnieszka JóZEFOWSKA Karolina WO?NICA Tomasz ZALESKI Department of soil science and soil Protection Institute of Soil Science and Agrophysics University of Agriculture in Krakow

The purpose of this research was to investigate the relationship between soil biota such as microbial activity,soil fauna(e.g.,earthworms and enchytraeids),and soil physical and chemical *** study area was located in Pieniny National Park(PNP)in the Carpathian Mountains in southern *** samples were collected from six forest monitoring areas of PNP from two soil layers(at 0–15 cm and 15–30 cm down,respectively).The investigated soils were classified to eutric cambisols and had silt or silt loam soil *** analysis,soil aggregate stability index was connected with other physical,chemical,and biological soil *** was noted that the stability index of 3 mm to 5 mm soil aggregates influenced pH and dissolved organic *** stability index of 2 mm to 3 mm soil aggregates was positively correlated with dissolved organic carbon,soil moisture,microbial biomass carbon,total organic carbon,total nitrogen,and enchytraeid density,and negatively correlated with bulk density,particle density,porosity,and permanent wilting *** stability index of 1 mm to 2 mm soil aggregates was positively correlated with total nitrogen,enchytraeid and earthworm density and negatively correlated with particle density,porosity,and permanent wilting *** study has shown what factors create a stable soil structure in the forest soils of PNP.

关键词： Aggregate stability Forest soils Microorganisms Earthworms Enchytraeids Physical properties Chemical properties

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Characterizing Spatial Variability of soil Textural Fractions and Fractal Parameters Derived from Particle Size Distributions

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Pedosphere 2019年第2期29卷 224-234页

作者： Meysam MOHAMMADI Mahmoud SHABANPOUR Mohammad Hossein MOHAMMADI Nasser DAVATGAR Department of soil science Faculty of Agriculture University of Guilan Department of soil science Faculty of Agricultural Engineering and Technology University of Tehran Department of soil science Research Institute of Soil and Water

soil particle size distribution(PSD) is a fundamental physical property affecting other soil properties. Characterizing spatial variability of soil texture is very important in environmental research. The objectives of this work were: 1) to partition PSD of 75 soil samples, collected from a flat field in the University of Guilan, Iran, into two scaling domains using a piecewise fractal model to evaluate the relationships between fractal dimensions of scaling domains and soil clay, silt, and sand fractions and 2) to assess the potential of fractal parameters as an index used in a geostatistical approach reflecting the spatial variability of soil texture. Features of PSD of soil samples were studied using fractal geometry, and geostatistical techniques were used to characterize the spatial variability of fractal and soil textural parameters. There were two scaling domains for the PSD of soil samples. The fractal dimensions of these two scaling domains(D_1 and D_2) were then used to characterize different ranges of soil particle sizes and their relationships to the soil textural parameters. There was a positive correlation between D_1 and clay content(R^2= 0.924), a negative correlation between D_1 and silt content(R^2= 0.801), and a negative correlation between D_2 and sand content(R^2= 0.913). The geometric mean diameter of soil particles had a negative correlation with D_1(R^2= 0.569) and D_2(R^2= 0.682). Semivariograms of fractal dimensions and soil textural parameters were calculated and the maps of spatial variation of D_1 and D_2 and soil PSD parameters were provided using ordinary kriging. The results showed that there were also spatial correlations between D_1 and D_2 and particle size *** to the semivariogram models and validation parameters, the fractal parameters had powerful spatial structure and could better describe the spatial variability of soil texture.

关键词： fractal dimension geometric mean diameter geostatistical approach physical property semivariogram model statistical correlation

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Prediction of kiwifruit firmness using fruit mineral nutrient concentration by artificial neural network(ANN) and multiple linear regressions(MLR)

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Journal of Integrative Agriculture 2017年第7期16卷 1634-1644页

作者： Ali Mohammadi Torkashvand Abbas Ahmadi Niloofar Layegh Nikravesh Department of soil science Science and Research Branch Islamic Azad University Department of soil science University of Tabriz

Many properties of fruit are influenced by plant nutrition. Fruit firmness is one of the most important fruit characteristics and determines post-harvest life of the fruit, in recent decades, artificial intelligence systems were employed for developing predictive models to estimate and predict many agriculture processes. In the present study, the predictive capabilities of multiple linear regressions （MLR） and artificial neural networks （ANNs） are evaluated to estimate fruit firmness in six months, including each of nutrients concentrations （nitrogen （N）, potassium （K）, calcium （Ca） and magnesium （Mg）） alone （P1）, com- bination of nutrients concentrations （P2）, nutrient concentration ratios alone （P3）, and combination of nutrient concentrations and nutrient concentration ratios （P4）. The results showed that MLR model estimated fruit firmness more accuracy than ANN model in three datasets （P1, P2 and P4）. However, the application of P3 （N/Ca ratio） as the input dataset in ANN model improved the prediction of fruit firmness than the MLR model. Correlation coefficient and root mean squared error （RMSE） were 0.850 and 0.539 between the measured and the estimated data by the ANN model, respectively. Generally, the ANN model showed greater potential in determining the relationship between 6-mon-fruit firmness and nutrients concentration.

关键词： artificial neural network firmness fruit kiwi multiple linear regression nutrient

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Apatite Loss in Pothwar Loess Plain(Pakistan) Fits a Simple Linear Reservoir Model

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Pedosphere 2014年第6期24卷 763-775页

作者： M.S.AKHTAR M.IMRAN A.MEHMOOD M.MEMON S.RUKH G.S.KIANI Department of soil science and soil Water Conservation PMAS-Arid Agriculture University Rawalpindi Department of soil science Sindh Agriculture University

Apatite is the dominant phosphorus(P) mineral in early stages of soil development, and its redistribution as labile forms under pedogenesis controls terrestrial bioavailability. Quantitative distribution of labile forms of P and apatite-P was examined in Pothwar Loess Plain, Pakistan where the degree of pedogenesis varied with relief. Four soil types, Typic Ustorthents(Rajar), Typic Calciustepts(Missa), Udic Calciustepts(Basal), and Udic Haplustalfs(Guliana), were sampled from three replicated locations at genetic horizon level. With the exception of total P value at surface, the mean total and apatite-P decreased towards the surface in Udic Haplustalfs and Udic Calciustepts where dicalcium and octacalcium phosphate increased toward surface. Iron(oxides and oxyhydroxides) adsorbed and occluded P forms were also in greater quantities in Udic Haplustalfs and increased toward the surface, whereas they were lowest and uniform in the Typic Ustorthents. Aluminum- and organic P correlated with soil organic matter. Apatite-P decreased exponentially with an increase in the sum of iron adsorbed and occluded P fractions, and fitted the equation M(x)= M0 [1- exp(-wx)] with r2= 0.996, where M(x)is the mean apatite-P concentration in solum, M0 is the apatite-P content in the loess sediments, x is the cumulative iron adsorbed and occluded P, and w is an empirical factor indicating the change rate of apatite-P in the loess. From the calculated apatite-P of 740 mg kg-1at the time of deposition, mean apatite-P loss was 60% in Udic Haplustalfs, 33% in Udic Calciustepts, 23% in Typic Calciustepts, and 8% in Typic Ustorthents. The transformation of soil P to labile forms was faster and deeper in level or slight depressions followed by gently sloping areas in wide plains, and was the least in the gullied land.

关键词： labile forms pedogenic iron oxides phosphorus distribution phosphorus fractions toposequence

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Vertical Distribution of soil Pyrogenic Matter: A Review

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Pedosphere 2019年第2期29卷 137-149页

作者： Eleanor HOBLEY soil science Technical University of Munich

Alteration of terrestrial biomass during fire produces pyrogenic matter, a large quantity of which is deposited on and may enter soils. The amount of annual burning around the globe implies greater production and storage of carbon in soil pyrogenic organic matter(pyrOM) than is regularly found in investigations of soil pyrogenic matter. A portion of this unaccounted for pyrogenic material may be translocated to subsurface soil depths, which is frequently excluded from soil investigations, and the presence of subsoil charcoal helps to partially fill this pyrOM gap. In this paper, I discuss the mechanisms for vertical redistribution of pyrogenic matter in soils and develop conceptual models to describe the depth, particle size, and age distribution of pyrogenic matter resulting from different translocation mechanisms. Based on the relationships between pyrogenic matter turnover and translocation, the suitability of pyrogenic matter in soils as an indicator for soil processes is discussed. Deciphering the relationships between pyrogenic matter depth, particle size, and age distribution yields valuable insights into the dynamics of soil forming processes as well as soil pyrogenic matter turnover,which should therefore, be a focus of future studies.

关键词： age black carbon charcoal mobility organic matter particle size subsoil translocation

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Salic Horizons in soils of the USA

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Pedosphere 2013年第5期23卷 600-608页

作者： J. G. BOCKHEIM A. E. HARTEMINK Department of soil science University of Wisconsin

The taxonomic hierarchy and nationwide distribution of soils with a salic horizon were studied using the USA Natural Resources Conservation Service soil Survey Geographic （SSURGO） Database to provide a more holistic view of the role of soil-forming factors in pedogenesis than from isolated case studies. soils with a salic horizon occupied an area of 11 000 km2, i.e., 0.1% of land area in the contiguous USA. These soils occur narrowly in three great groups （Aquisalids, Haplosalids and Halaquepts）, 11 subgroups, and 97 soil series. soils with a salic horizon commonly had a mesic （50% of soil series） or thermic （19%） soil-temperature class, an aquic （89%） soil-moisture class, a mixed mineral class （79%）, a calcareous （52%） reaction class, a superaztive （59%） cation exchange activity class, and a fine （24% of soil series）, fine-loamy （24% of soil series）, or fine-silty （19% of soil series） particle-size class. soils with a salic horizon were concentrated in the Basin and Range Province of western USA. The key pedogenic processes leading to the development of salic horizons were salinization, gleization, and calcification, with some evidence for argilluviation and silicification.

关键词： saline soils soil classification solonchak

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Effects of environmental factors on classification of loessderived soils and clay minerals variations, northern Iran

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Journal of Mountain science 2018年第5期15卷 976-991页

作者： Mohammad AJAMI Ahmad HEIDARI Farhad KHORMALI Manouchehr GORJI Shamsollah AYOUBI Department of soil science College of Agriculture and Natural Resources University of Tehran Department of soil science Faculty of Water and Soil Engineering Gorgan University of Agricultural Sciences and Natural Resources Department of soil science College of Agriculture Isfahan University of Technology

Land-use type under different topographic conditions and human activities affects soil development. We investigated the effects of land-use,topography and human activity on soil classification changes in the Toshan watershed in northern *** representative pedons derived from loess parent materials were studied on different land-uses and topographic positions. The studied pedons in forest(FO) on backslopes and footslope were classified as Calcic Haploxeralfs and Typic Haploxeralfs, respectively. The soils in abandoned lands(AB) and orchards(OR), where formerly under natural forests, located on the shoulder and backslopes positions were classified as Calcic Haploxeralfs and Vertic Haploxeralfs, ***-developed argillic horizons as indicators for higher degrees of soil evolution were observed in more-stable areas under the natural forest or less disturbed areas. Clay lessivage through these soil profiles have led to formation of Typic or Calcic Haploxeralfs, while under croplands(CP) were classified as Typic Calcixerepts. Conversion of sloping deforested areas to CP along with inappropriate management have accelerated soil erosion, resulting in unstable conditions in which decalcification and formation of developed soils cannot occur. Paddy cultivation in flat areas has caused to reduced conditions and formation of Typic *** of unfavorable conditions for chemical weathering(e.g. lower water retention compared to more-stable areas) no vermiculite was detected in the CP. The results showed that evolution and classification of the studied soils were strongly affected by land-use type, topography and management.

关键词： soil classification Clay mineralogy Land-use change Topography Loess

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Wheat-Exuded Organic Acids Influence Zinc Release from Calcareous soils

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Pedosphere 2011年第5期21卷 657-665页

作者： M.A.MAQSOOD S.HUSSAIN T.AZIZ M.ASHRAF Institute of soil and Environmental sciences University of Agriculture Department of soil science University of Sargodha

Rhizosphere drives plant uptake of sparingly soluble soil zinc(Zn).An investigation with three experiments was conducted to study organic acid exudation by two contrasting wheat genotypes(Sehar-06 and Vatan),Zn fractions in 10 different calcareous soils from Punjab,Pakistan,and release of different soil Zn fractions by organic *** two genotypes differed significantly in biomass production and Zn accumulation under deficient and optimum Zn levels in nutrient *** a deficient Zn level,Sehar-06 released more maleic acid in the rhizosphere than *** soils used in the present study had very different physicochemical properties;their total Zn and Zn distribution among different fractions varied *** release behaviour was determined by extracting the soils with 0.005 mol L-1 citric acid or maleic *** parabolic diffusion model best described Zn release as a function of *** diffusion model fitting indicated more maleic acid-driven than citric acid-driven soil Zn mobility from different *** Zn release in six consecutive extractions during 24 h ranged from 1.85 to 13.58 mg kg-1 using maleic acid and from 0.37 to 11.84 mg kg-1 using citric *** the selected calcareous soils,the results of stepwise linear regression indicated significant release of Fe-Mn oxide-bounded soil Zn by maleic acid and its availability to the Zn-effcient ***,release of maleic acid by plants roots played an important role in phytoavailability of Zn from calcareous soils.

关键词： citric acid maleic acid phytoavailability plant uptake rhizosphere

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Phenological Stage, Plant Biomass, and Drought Stress Affect Microbial Biomass and Enzyme Activities in the Rhizosphere of Enteropogon macrostachyus

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Pedosphere 2019年第2期29卷 259-265页

作者： Kevin Z.MGANGA Bahar S.RAZAVI Muhammad SANAULLAH Yakov KUZYAKOV Department of soil science of Temperate Ecosystems Institute of Soil Science University of G?ttingen Department of Range and Wildlife sciences South Eastern Kenya University Department of Agricultural soil science Institute of Soil Science University of G?ttingen Institute of soil and Environmental sciences University of AgricultureFaisalabad Institute of Environmental sciences Kazan Federal University

Indigenous grasses have been effectively used to rehabilitate degraded African drylands. Despite their success, studies examining their effects on soil bioindicators such as microbial biomass carbon(C) and enzyme activities are scarce. This study elucidates the effects of drought stress and phenological stages of a typical indigenous African grass, Enteropogon macrostachyus, on microbial biomass and enzyme activities(β-glucosidase, cellobiohydrolase, and chitinase) in the rhizosphere soil. Enteropogon macrostachyus was grown under controlled conditions. Drought stress(partial watering) was simulated during the last 10 d of plant growth, and data were compared with those from optimum moisture conditions. The rhizosphere soil was sampled after 40 d(seedling stage), 70 d(elongation stage), and 80 d(simulated drought stress). A high root:shoot ratio at seedling stage compared with elongation and reproduction stages demonstrated that E. macrostachyus invested more on root biomass in early development, to maximise the uptake of nutrients and water. Microbial biomass and enzyme activities increased with root biomass during plant growth. Ten-day drought at reproduction stage increased the microbial biomass and enzyme activities, accompanying a decrease in binding affinity and catalytic efficiency. In conclusion, drought stress controls soil organic matter decomposition and nutrient mobilization, as well as the competition between plant and microorganisms for nutrient uptake.

关键词： African grass catalytic efficiency cellobiohydrolase chitinase β-glucosidase nutrient uptake optimum moisture soil bioindicators

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