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Impact of enclosure management on soil properties and microbial biomass in a restored semi-arid rangeland, Kenya

Journal of Arid Land 2014年第5期6卷 561-570页

作者： Stephen M MUREITHI Ann VERDOODT Charles KK GACHENE Jesse T NJOKA Vivian O WASONGA Stefaan De NEVE Elizabeth MEYERHOFF Eric Van RANST Laboratory of soil science Department of Geology and Soil Science Ghent University department of Land Resources Management and Agricultural Technology University of Nairobi Research Unit of soil Degradation and Conservation Department of Soil Management Ghent University Rehabilitation of Arid Environments Trust

Rangeland degradation is a serious problem throughout sub-Saharan Africa and its restoration is a challenge for the management of arid and semi-arid areas. In Lake Baringo Basin of Kenya, communities and individual farmers are restoring indigenous vegetation inside enclosures in an effort to combat severe land degradation and address their livelihood problems. This study evaluated the impact of enclosure management on soil properties and microbial biomass, being key indicators of soil ecosystem health. Six reseeded communal enclosures using soil embankments as water-harvesting structures and strictly regulated access were selected, varying in age from 13 to 23 years. In six private enclosures, ranging from 3 to 17 years in age, individual farmers emulated the communal enclosure strategy and restored areas for their exclusive use. Significant decreases in bulk density, and increases in the soil organic carbon, total nitrogen and microbial biomass contents and stocks were found in the enclosures as compared with the degraded open rangeland. In the private enclosures, the impact of rehabilitation on the soil quality was variable, and soil quality was in general lower than that obtained under communal management. The significant increase of absolute stocks of carbon, nitrogen and microbial biomass compared to the degraded open rangeland indicates the potential for the restoration of soil quality through range rehabilitation. Over-sowing with indigenous legume fodder species could improve total nitrogen content in the soil and nutritional value of the pastures as well.

关键词： rangeland degradation enclosures microbial biomass rehabilitation reseeding soil quality Kenya

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Discovery of the chitinozoans Belonechitina capitata from the Shiala Formation of northeastern Garhwal-Kumaon Tethys Himalaya,Pithoragarh District, Uttrakhand, India

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Geoscience Frontiers 2016年第5期7卷 859-864页

作者： H.N.Sinha Jacques Verniers department of geology Vinoba Bhave University Hazaribag 825301 India Research Unit Palaeontology Department of Geology and Soil Science WE13 Ghent University Belgium

Belonechitina capitata, a typically middle to late Ordovician chitinozoan index taxon was for the first time recovered from the northeastern Kumaon region, a part of Garhwal-Kumaon Tethys basin of the Himalaya, India. This species is of great biostratigraphic importance and has already been reported from Avalonia, Baltica and northern Gondwana. The study area was during Ordovician, part of a lowpalaeolatitudinal Gondwana region. The vesicles of recovered forms are black and fragmentary. This is principally attributed to intense tectonic activity during the Himalayan orogenic movement which resulted into high thermal alteration. The chitinozoans are found along with melanosclerites.

关键词： Chitinozoan(Belonechitina capitata) Ordovician Northeastern Kumaon Tethys Himalaya Low palaeolatitudinal Gondwana Shiala Formation

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Paleoecology of Benthic Foraminifera in Coral Reefs Recorded in the Jurassic Tuwaiq Mountain Formation of the Khashm Al-Qaddiyah Area, Central Saudi Arabia

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Journal of Earth science 2015年第2期26卷 224-235页

作者： Mohamed Youssef Abdelbaset S.El-Sorogy department of geology and Geophysics College of Science King Saud University department of geology Faculty of Science South Valley University department of geology Faculty of Science Zagazig University

Thirty three benthic foraminiferal species belong to 23 genera and 16 families have been recorded from the coral reefs of the Callovian Tuwaiq Formation, Khashm AI-Qaddiyah area, Central Saudi Arabia. Three species： Astacolus qaddiyahensis, Nodosaria riyadhensis, Siderolites jurassica are believed to be new. Nearly all identified foraminifera are of Atlantie-Miditeranean affinity. The foraminiferal assemblage recorded in the present work is mixed of open marine, moderately deep marine conditions associations and shallow to deep lagoon. The reefal part of upper Twiaq Formation may have been deposited in shallow water of lower to middle shelf depth （20-50 m） as indicated by abundant corals and benthic foraminifera. The coral fauna and bearing benthic foraminifera indicated moderate water energy.

关键词： coral reef benthic foraminifera Jurassic Tuwaiq Formation Saudi Arabia.

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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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Bryozoan Nodules as a Frame-Builder of BryozoanMicroreef, Middle Miocene Sediments, Egypt

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Journal of Earth science 2015年第2期26卷 251-258页

作者： Abdelbaset S.El-Sorogy geology and Geophysics department College of Science King Saud University geology department Faculty of Science Zagazig University

Bryozoan nodules, coralline algae, scleractinian corals and oysters form an important organic buildup, 1.2-4.5 m thick in the Langhian-Serravaliann sediments of Egypt. Based on type, shape and size of the substrate, bryozoan nodules take tree-like and globular morphologies. Tree-like speci- mens reach 10 cm in maximum height and 3 cm in diameter, while Globular ones attain 9 cm in maxi- mum diameter. Most tree-like nodules are perforated with wide or narrow pores, few are non-perforated. Globulars and few tree-like forms are with mamelon-like structures. Perforations on the outer surfaces may indicate a symbiotic relationship between bryozoans and a live plant substrate. Nod- ules from Homiera and Gharra areas of the Cairo-Suez District with wider perforations may indicate growth in slightly lighter or turbid areas of the continental shelf than those of North Western Desert of narrower perforations. Non-perforated nodules may assume an incrustation on ephemeral substrate .

关键词： Miocene bryozoa frame builder microreef paleoecology Egypt.

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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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Geochronological Constraints on the Haftcheshmeh Porphyry Cu-Mo-Au Ore Deposit, Central Qaradagh Batholith, Arasbaran Metallogenic Belt, Northwest Iran

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Acta Geologica Sinica(English Edition) 2017年第6期91卷 2109-2125页

作者： Shohreh HASSANPOUR Mohsen MOAZZEN department of geology Payame Noor University Natural science Faculty Geology DepartmentTabriz University

The Haftcheshmeh porphyry Cu-Mo-Au deposit in the Arasbaran metallogenic belt （AMB） of NW Iran contains more than 185 Mt of ore, with a grade ranging from 0.3% to 0.4%. It is hosted within a porphyritic diorite to granodiorite intruded into an older gabbro - diorite intrusion. 40Ar/39Ar analyses of primary magmatic hornblende from the granodiorite porphyry and gabbro - diorite show plateau ages of 26.41 ± 0.59 Ma, with an inverse isochron age of 25.9 ± 1.0 Ma and a plateau age of 27.47 ± 0.17 Ma, with an inverse isochron age of 27.48 ± 0.35 Ma for these two rock types, respectively. Comparing these new age data with those from the nearby Sungun （20.69 ± 0.35 Ma） and Kighal porphyry deposits defines a northwest-southeast Cu-Mo-Au mineralization zone extending for 20 km over the time span of-27 to 20 Ma. Geochemically, Haftcheshmeh rocks are calc-alkaline with high potassium affinities with tectonic setting in relation to volcanic arc setting. Large ion lithophile elements （LILE） such as Th, U and K show enrichment on a primitive mantle normalized diagram （specially Pb）, and are depleted in high field strength elements （HFSE） such as Ti and Nb, pointing to a mantle magma source contamination with crustal materials by subducted oceanic crust.

关键词： 40Ar/39Ar dating Haftcheshmeh porphyry Cu-Mo deposit Arasbaran Metallogenic Belt,Northwest Iran

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Numerical Modelling of Seismic Site Effects Incorporating Non-linearity and Groundwater Level Changes

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Journal of Earth science 2010年第6期21卷 931-940页

作者： Dominik Ehret Joachim Rohn Dieter Hannich Carlos Grandas Gerhard Huber department of Applied geology University of Erlangen-Nuremberg department of Applied geology University (TH) of Karlsruhe Institute of soil and Rock Mechanics University (TH) of Karlsruhe

In the past decades, the necessity for detailed earthquake microzonation studies was recognized worldwide. Therefore, different approaches were established and applied. Unfortunately, the majority of these approaches are not based on pre-existing field data but require extensive seismic measurements and investigations. Furthermore, these approaches incorporate non-linearity inadequately and cannot take groundwater level changes into account. For this purpose, notably numerical models are most suitable. These models require a good knowledge of the local geological conditions （especially of the uppermost unconsolidated units）, information about the geotechnical parameters of these units, and a hydrogeological model of the investigated area. Most of this information can be obtained from geotechnical investigations and surveys that have already been carried out in most densely populated areas. In a case study for Bucharest City, non-linear analyses were performed using software that is based on the visco-hypoplastic constitutive law. The results indicate that groundwater level changes have an important influence on duration and amplitude of ground response and thus should be considered for seismic microzonation studies. This approach ean be used to display site effects and to identify different microzones taking different earthquake magnitudes and groundwater levels into account.

关键词： microzonation site effect visco-hypoplasticity non-linearity Bucharest Romania.

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