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The use of vertical electric dipole transmitter and receiver turns out to be advantageous in the exploration of lateral inhomogeneities of high resistivity layers by transillumination measurement. Geological information can be made clearer by transformation of the amplitude response to apparent resistivity spectrum. The apparent resistivity calculated by the geometric factor in the quasistationary frequency range depends decisively on the galvanic effect of the high resistivity layer containing the electrodes. In the so called frequency dependent inductive apparent resistivity deduced based on the amplitude response of the uniform half — respectively full — space at low frequencies mainly the effect of the shoulder formation, at frequencies high enough the effect of the resistive layer containing the electrode will dominate. The knowledge of these apparent resistivities on the one hand helps the determination of the effective resistivity, which is independent of the ray-length and indicates the continuity or discontinuity of the resistive layer along the equatorial plane. On the other hand in the case of transilluminations with areal coverage they can be used in the selection of the horizontal-layered, uniform start model, needed in the reconstruction of the spatial distribution of the resistivity-variation. Reconstructions of measured and simulated data demonstrate the applicability of the procedure.

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Gy Bárdossy and J Fodor: Evaluation of Uncertainties and Risks in Geology. Springer-Verlag, 2004

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Numerical studies indicate that information can be gained about the layering even in the transition zone of the source, down to a considerable depth with a properly planned frequency sounding measuring system. As it has been demonstrated, the high resistivity basement can be revealed even with a source-receiver separation 2-times larger than its depth.Model studies demonstrate that the transformation of the measured field into the so-called effective resistivity — with the use of a set of homogeneous earth responses calculated for several different resistivity values — offers a useful tool in the controlled electric bipole source measurement. Effective resistivity frequency sounding curves in the transition zone also give information about layering, and make additional transformations useful in preliminary interpretation.Effective resistivity sounding curves of arbitrary configuration can be determined from any individual field amplitude and phase, or from quantities derived from them. Therefore they can be applied for single — either electric or magnetic — field component frequency sounding as well.

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Possibilities of detection of abrupt lateral conductivity changes are presented by mapping of the surface vertical magnetic field in the vicinity of the borehole. Magnetic field components generated by vertical electric bipole do not exist over a uniform or horizontally layered earth. Vertical magnetic field is caused exclusively by resistivity inhomogeneities. Therefore it is very sensitive to lateral discontinuities. A simplified inversion procedure — searching the anomalous subsurface horizontal current distribution linked with the discontinuity — is discussed and tested on synthetic examples.

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Current density pseudosections derived by filtering and probability tomography from calculated VLF vertical magnetic profiles over synthetic 2D targets with geometrical shape are examined critically. It was found that the position and shape of  target only in the case of single inhomogeneities with very limited cross-sectional area and simple shape can be revealed reliably by them. The locations of sharp cross-sectional boundaries can only be guessed. Fictitious, misleading current-density indications occur in the case of laterally extended, or multiple targets at too wide filter windows. Both procedures suppose that the measured values originate in the superposition of the magnetic fields of individual stationary current-lines inside the target. It is shown that in the quasistationary range the shape and position of the target can be outlined sharply using this simplified form of the forward problem solution and performing an inversion with respect of the vertices of the polygon approximating the cross-sectional contour of the target. Several kinds of inversionprocedures  were tested.

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The main objective of the DOSoReMI.hu (Digital, Optimized, Soil Related Maps and Information in Hungary) project is to significantly extend the potential, how demands on spatial soil related information could be satisfied in Hungary. Although a great amount of soil information is available due to former mappings and surveys, there are more and more frequently emerging discrepancies between the available and the expected data. The gaps are planned to be filled with optimized digital soil mapping (DSM) products heavily based on legacy soil data, which still represent a valuable treasure of soil information at the present time. The paper presents three approaches for the application of Hungarian legacy soil data in object oriented digital soil mapping.

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A talajok tulajdonságainak javítása céljából végzett bioszénnel történő kezelések hatása a különböző fizikai, kémiai és biológiai tulajdonságú talajok esetében még nem teljesen ismert. Kísérleteinket homoktalajon végeztük az MTA ATK TAKI Őrbottyánban lévő kísérleti telepén, ahol kukoricát vetettek. Hét kezelést vizsgáltunk, négy ismétlésben. Három esetben a talaj különböző dózisban bioszenet és konstans dózisú műtrágyát tartalmazott (0,1 m/m%; 0,5 m/m%; 1 m/m%; jelölésük BC0,1M; BC0,5M; BC1,0M), három esetben pedig a fent említett bioszén dózisokat egységesen 10 t/ha komposzttal egészítettük ki (BC0,1K; BC0,5K; BC1,0K). Ezek mellett pedig kialakítottunk egy bioszén és komposzt mentes abszolút kontroll (K) kezelést is. Kutatásunk során talajszondákkal monitoroztuk a talajnedvességtartalmának alakulását, valamint statikus kamrás mintavételi eljárással a talajlégzést is mértük a kezelésekben.

A talajnedvesség éves átlagát nézve 1% bioszénnel és komposzttal kezelt parcella esetében a talaj nedvességtartalma nem szignifikáns mértékben növekedett a bioszén és komposzt mentes abszolút kontroll környezethez képest. Csapadékesemények alkalmával az 1% bioszenet és komposztot tartalmazó parcellában nőtt meg legjobban a talajnedvesség, illetve hasonlóan alakult a nedvességtartalom a 0,5% bioszénnel kezelt műtrágyás parcellában is. Csapadékesemények után az összes bioszenet és műtrágyát, illetve bioszenet és komposztot tartalmazó parcellában gyorsabban száradt ki a talaj a kontrollhoz képest. A csapadékban szegényebb, szárazabb időszak alkalmával egyedül az 1% bioszenet és komposztot tartalmazó kezelés talajnedvessége volt magasabb a kontrollhoz képest, a 0,5% bioszénnel és műtrágyával kezelt, komposzt mentes esetben a nedvesség hasonlóan alakult a kontrollhoz viszonyítva, az összes többi esetben jóval az alatt maradtak az értékek.

Összességében megállapítható, hogy a komposztot tartalmazó talajok érzékenyebben reagáltak a csapadékra, a legjobb vízgazdálkodást az 1% bioszén és komposzt kezelés esetében értük el. Önmagában a bioszén nagy mennyiségű (1,0 m/m%) adagolása nem volt egyértelműen talajnedvesség-növelő hatású.

A bioszén szén-dioxid forgalomra történő hatását a talajlégzés mérésével vizsgáltuk. A bioszénnel, valamint műtrágyával kezelt és a kontroll kezelések között csak néhány esetben volt különbség. A komposzttal kevert bioszén kezelések alkalmával hasonló eredményre jutottunk, mint a műtrágyával kevert bioszén esetében. Eredményeink alapján arra következtethetünk, hogy a talajlégzés nem függött a bioszén dózisától. A bioszén talajlégzésre gyakorolt hatása közvetett módon, a talajnedvesség befolyásolásán keresztül valósul meg, mivel bioszenet alkalmazva bizonyos esetekben a talajnedvesség emelkedett a kontrollhoz képest, ekkor a talajlégzés ugyancsak magasabb lett, amely jelenség a komposzttal kezelt esetekben jól megfigyelhető volt.

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Agrokémia és Talajtan
Authors:
Péter Csathó
,
E. Osztoics
,
J. Csillag
,
T. Lengyel
,
L. Gonda
,
L. Radimszky
,
G. Baczó
,
M. Magyar
,
K. R. Végh
,
M. Karátsonyi
,
T. Takács
,
A. Lukács
, and
T. Németh

Depending on their origin, sedimentary phosphate rocks (PRs) may differ in their P solubility, and, as a consequence, in their agronomic effectiveness. The effect of six phosphate rocks (PR) - originating from Algeria (ALG), North Florida (FLO), North Carolina (NCA), Senegal (SEN) Morocco (MOR) and Hyperphosphate (HYP) with various P solubility (evaluated by 2% formic acid, 2% citric acid, and neutral ammonium citrate) - as well as single superphosphate (SSP) and superphosphate + lime (SSP + Ca) (each P source on 4 P levels, with doses of 0, 100, 400 and 1600 mg P 2 O 5 ·kg -1 soil) on the shoot yield of tillering stage spring barley, soil available P (i.e. H 2 O, Olsen, Bray1, Lakanen-Erviö (LE) and ammonium lactate (AL) extractable P contents) were studied in pot experiments set up with acidic sandy soil (Nyírlugos, Hungary) and acidic clay loam soil (Ragály, Hungary), both with low P supplies.  The average spring barley shoot yield at the beginning of shooting was 95% higher on the colloid-rich acidic (pH KCl : 4.5) clay loam soil than on the colloid-poor acidic (pH KCl : 3.8) sandy soil. The differences in the solubility of phosphate rocks showed close correlation to the differences in P responses. On both soils, the correlation between total PR-P added and P responses in spring barley shoot yield was much weaker than that between neutral ammonium citrate soluble PR-P added and P responses in spring barley shoot yield. When phosphate rocks were applied as P sources, the comparison of soil test P methods showed a different picture on the two soils. In the case of the acidic sandy soil (Nyírlugos), the strongly acid LE-P (r² = 0.83) and AL-P (r² =0.74) tests gave the highest correlation coefficients with spring barley responses to P, while on the acidic clay loam soil (Ragály) these were achieved by the Olsen-P (r² = 0.88) and Bray1-P (r² =0.88) methods. 

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