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Wyszukujesz frazę "soil salinity" wg kryterium: Temat


Wyświetlanie 1-4 z 4
Tytuł:
Alterations of some chemical and physico-chemical properties of selected soils in field ecosystems
Autorzy:
Laskowski, S
Toloczko, W.
Powiązania:
https://bibliotekanauki.pl/articles/1450264.pdf
Data publikacji:
2001
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
soil chemistry
physicochemical property
chemical property
soil
soil salinity
geoecology
organic carbon
terrestrial ecosystem
macroelement
arable soil
Opis:
The research was conducted in 1991-1997 on the soils from arable fields situated near Łódź. To the detailed research there were stated four soil profiles which were different as regards their grain composition (two sand and two silt soils, all shallow) and typology (two profiles of brown leached soils, one pseudopodzolic-gley soil and one fallow glossic grey-brown podzolic soil). Qualification of the directions of the alterations in the content of organic carbon and basic macroelements (P, K, Mg) in soil and hesitation of reaction, hydrolytic acidity and content of the exchangeable basic cations in the soil sorptive complex were the main target of our research. The result of the 7-year-long research showed that different changes took place in the features of the examined soils. However, the exact assignment of the direction of these alteractions is extremely complex and does not warrant getting a satisfying answer. It is the result of taking various agriculture actions which are necessary to the appropriate maintenance of the ecosystems.
Źródło:
Acta Agrophysica; 2001, 50; 177-188
1234-4125
Pojawia się w:
Acta Agrophysica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wplyw fizycznych wlasciwosci gleby na elektryczne parametry ukladu elektrody-gleba w aspekcie pomiaru jej wilgotnosci i zasolenia
Influence of soil physical properties on electrical parameters of electrodesisoil system in aspect of the determination of soil moisture and salinity
Autorzy:
Malicki, M A
Powiązania:
https://bibliotekanauki.pl/articles/1628320.pdf
Data publikacji:
1993
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
agrofizyka
gleby
wilgotnosc
zasolenie
badania gleboznawcze
pomiary elektryczne
wlasciwosci fizyczne
elektrody
agrophysics
soil
moisture
soil salinity
soil research
electrical measurement
physical property
electrode
Opis:
Możliwość monitoringu parametrów wody glebowej jest warunkiem koniecznym kontrolowania oraz matematycznego modelowania procesów zachodzących w kontinuum gleba-roślina-atmosfera, a więc i prognozowania ich następstw. Biorąc pod uwagę, żc integrowalne we współczesnych cyfrowych systemach akwizycji danych są wyłącznie czujniki "czytane" elektrycznie, należy dysponować elektrycznymi czujnikami agrofizycznych parametrów wody (patr2 część l). Istotne spośród tych parametrów -wilgotność gleby oraz jej zasolenie, łatwe do bezpośredniego zmierzenia w laboratorium, są zarazem najtrudniejsze do odczytu elektrycznego. Niniejsza rozprawa dotyczy poszukiwań metody pomiaru elektrycznych parametrów gleby oraz sposobu ich interpretacji w kategoriach wilgotności i zasolenia. Dla ułatwienia identyfikacji dyskutowanych zmiennych ich symbole, oddzielone przecinkami, są wtrącane w tekst. Np.: "względna elektryczna przenikalność gleby, e, decydująca o elektrycznej pojemności układu elektrodyigleba..,", "elektryczna konduktywność gleby, ekG, zależna od wilgotności gleby, 6, oraz od elektrycznej konduktywności elektrolitu (wody glebowej), ekG,..." itp. Dla zaznaczenia granic faz występujących w szeregu elektrochemicznym tworzonym przez układ dwu elektrod w glebie, przyjęto stosowany w elektrochemii sposób dzielenia nazw tych faz pionową kreską. Np.: "układ elektrodyigleba...", "granica elektrodiroztwór..." itp. Ten sposób podkreśla występowanie bezpośredniego kontaktu elektrycznego pomiędzy dyskutowanymi fazami.Trzon rozprawy tworzą cztery zasadnicze części: 2,3,4, i 5 w skrócie omówione niżej.
The possibility to monitor soil water status is an indispensable condition to control as well as to model processes occuring in the soil-plant-atmosphere continuum. Taking into consideration that only these sensors can be integrated in modern data acquisition systems that are read electrically, it becomes clear that the sensors for soil moisture and salinity must be electrical. Continuously undertaken since the end of the previous century attempts to evaluate soil moisture from soil electrical conductivity or electrical permittivity as derived from the measurements of an ElectrodeslSoil System (ESS ) impedace has not brought electrical methods sufficiently reliable to be widely applied. Calibration curves, i.e. the soil moisture-electrical resistance or moisture-electrical capacitance relationships have proved to be strongly affected by frequency of the applied electrical field as well as by the soil temperature, salinity, texture and bulk density. The theory of dielectrics when applied lo soil cannot explain such phenomena as: enormous rise of electrical resistance and capacitance of the ESS with the frequency decrease, excessive influence of temperature and salinity on electrical capacitance of the ESS, and also a particularly strange phenomenon that: at the same geometry of the system and the same frequency of the applied electrical field, ESS with pure solution can reveal smaller electrical capacitance than that with saturated soil. Because of increasing interest in utilization of electrical properties of soil in order to gain information on the soil moisture and salinity, a search for a model explaining behavior of the HSS, when applied as a sensor for soil moisture and/or salinity, was undertaken. Part 2 of the presented dissertation describes an attempt to find a qualitative model of such a sensor, i.e. a model of the ESS (Electrodes\Soil System). The HSS under consideration is a system consisting of two bare electrodes and soil within their electrical field. The proposed model follows equivalent electrical circuits of impedance of the electrodelsolution interface like that applied in electrochemistry for considering kinetics of electrode processes. The model is based on clectrical polarization phenomena, including the interfacial one. It was shown that the ESS should be considered as an electrolytic cell where the soil pore water is the electrolyte. Its electrical impcdance is the resultant of several component subimpedances arising from a diversity of phenomena causing the sensor electrical polarization. It was shown that within the range of commonly applied frequencies below 108 Hz, readings of electrical capacitance, C, of the sensor (i.e. the ESS) were totally masked by interfacial pseudocapacitance while readings of the sensor electrical resistance, R, were affected by interfacial phenomena unless a special impedance bridge was applied which compensates for capacitive component of the sensor impedance. Numerical solution of the model was verified by comparison of its computer generated impedance-frequency characteristics with experimental data. The data concerned measurements of the C and R in-parallel equivalents of the ESS impedance, read within the frequency band ranged from 5*101-105 Hz. Then the numerical model was solved for a wide band of frequencies lOMO14 Hz. The solution brought to the conclusion that for the electrocapacitive measurements of the soil moisture the applied frequency should fall within the range of 108—1010 Hz, whereas for the electroresistive measurements of the soil moisture and/or salinity the frequency should fall within the range of HJ3-107 Hz, Recent advances in generation of fast rising pulses has resulted in the application of Time Domain Reflectometry (TDR) for measurements of soil electrical permittivity (thus also moisture) and electrical conductivity (thus also salinity). Ihis technology is particularly suitable for the determination of electrical permittivity of conducting media, like the soil, because it operates with a pulse having its leading edge composed of frequencies from the range 10s— ] 010 Hz, recommended for readings of electrical permittivity of the soil. The technology of TDR is continuously developed in The Institute of Agrophysics, Polish Academy of Sciences and brought to a TDR apparatus for simultaneous measurements of the soil electrical permittivity, conductivity and temperature, from which the soil moisture and salinity can be determined, as discussed below in part 3 and 4. Part 3 of the dissertation concerns reduction of influence of soil matrix on dielectric readings of the soil moisture. Samples of soils, soil-like, and also other capillary-porous materials were analysed using TDR with the aim of determining the contribution of material bulk density, thus also porosity, to the electrical permittivity-water content conversion function. The study showed that bulk density, thus also porosity, substantially affects the permittivity-moisture relationship. Two equivalent, empirical, normalized conversion functions were found - one accounting for bulk density and the other for porosity effect. Each of them, when applied to the dielectric TDR determinations of moisture, doubled precision of the determinations, independent of the material bulk density, thus also porosity. Part 4 of the dissertation concerns the possibility of interpretation of simultaneous readings of soil electrical permittivity and conductivity in terms of the soil salinity. When analyzing relationships between soil bulk clectrical conductivity, ecG, and its bulk relative electrical permittivity, e, it was found (for the investigated mineral soils) that within the range of volume water content, 6, from about 0.2 up to saturation the derivative 3ecG/3e is moisture independent and is directly proportional to the soil salinity. It was found that the variable SX=3eeG/5e, determined from in situ measurements of ecG(Q>0.2) and e(6>0.2), can be considered as an index of relative salinity of the soil. It was shown that knowing the salinity index, SX, and also sand content, it was possible to calculate electrical conductivity of soil pore water which is a widely accepted measure of the soil salinity. This way the possibility for nondestructive monitoring of salt migration in the soil became realistic. This possibility was experimentally verified in a column experiment by recording time and spatial variability of non-steady salt flow parameters (break-through curves). Original methodical solutions of the measurements and their experimental embodiments are described in part 5 of the dissertation. It contains detailed description of: a variable ratio arm impedance bridge for the determination of the capacitive-resistive impedance of the ESS, a programme for numerical solution of the frequency dispersion of the ESS impedance, TDR in application for the determination of electrical permittivity and conductivity of soil.
Źródło:
Acta Agrophysica; 1993, 0; 107
1234-4125
Pojawia się w:
Acta Agrophysica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zagadnienie doboru czestotliwosci pola elektrycznego w dielektrycznym pomiarze wilgotnosci gleb zasolonych
Autorzy:
Malicki, M A
Skierucha, W.
Powiązania:
https://bibliotekanauki.pl/articles/1402584.pdf
Data publikacji:
2001
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
gleby
gleby zasolone
zasolenie gleb
wilgotnosc gleby
pomiary wilgotnosci
pole elektryczne
metody dielektryczne
soil
salty soil
soil salinity
soil moisture
moisture measurement
electrical field
dielectric method
Źródło:
Acta Agrophysica; 2001, 53; 109-115
1234-4125
Pojawia się w:
Acta Agrophysica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Metodyczne zagadnienia monitoringu statusu wody w wybranych materialach biologicznych
Methodical questions of monitoring of water status in selected biological materials
Autorzy:
Malicki, M A
Powiązania:
https://bibliotekanauki.pl/articles/1630378.pdf
Data publikacji:
1999
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
agrofizyka
materialy biologiczne
zboza
ziarno
drewno
gleby
woda glebowa
wilgotnosc gleby
wilgotnosc ziarna
wilgotnosc drewna
temperatura
zasolenie gleb
potencjal wodny gleby
pomiary wilgotnosci
natlenienie
monitoring
agrophysics
biological material
cereal
grain
wood
soil
soil water
soil moisture
grain moisture
wood moisture
temperature
soil salinity
soil water potential
moisture measurement
oxygenation
Opis:
Methodical questions of monitoring of water status in soil, cereals grain and wood are discused ( where monitoring is understood as registration of time and spatial variability of selected properties). Amount of viariables which is necessary in order to determine water status depends on the complexion of the considered phenomena and is, so far, the matter of arbitrary choice. In most practical cases the water status is expressed only by moisture of the considered material ( like the building timber). In practical terms, two variables suffice to express water status in cereal grain: moisture and temperature. To describe water status in the soil not less then five variables are needed: amount of water (the soil moisture) soil water potential, salinity, oxygenation and temperature. The only sensors that can be integrated in modern data acquisition system must be read electrically. Therefore electroresistance and electrocapacitance methods were considered. Dielectric sensors were recognized as the proper choice.Soil is a complex material having instable characteristics. For this reason it is the most difficult task to monitor soil water status, particularly to determine the soil moisture. Therefore it has been assumed that measuring methods verified for the soil will be also suitable for other, less complex materials. Thus, monitoring of soil water status was mainly discussed. Special attention was focused to the time domain reflectometry, TDR, as the semi selective method for the soil moisture and salinity determination.
Źródło:
Acta Agrophysica; 1999, 19; 1-108
1234-4125
Pojawia się w:
Acta Agrophysica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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