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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Irrigation science 8 (1987), S. 35-48 
    ISSN: 1432-1319
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Lucerne was irrigated for three years on a slowly permeable, duplex soil, with saline water up to 2.4 dS m−1 without significant yield decline. Irrigation water of 4.5 dS m−1 significantly reduced yield. Lucerne yield was most closely related to the soil ECe of the 0–15 cm depth, rather than the total rootzone, and was described by; Relative yield=100−6.5 (ECe-2.1). While lucerne roots reached depths of at least 150 cm, approximately 80% of total root length was located in the 0–60 cm depth. Increasing salinity increased the plant concentrations of sodium and chloride, however, these changes were not closely related to changes in yield. Soil salinity increased with increasing salinity of the applied water. However, during the irrigation season water penetration and the accumulation of salt within the profile was predominantly restricted to the 0–60 cm depth. No portion of the applied irrigation water was available as a leaching fraction. Any leaching of salts to the watertable, particularly below 120 cm, was due to winter rainfall rather than the application of summer irrigation water. Ripping the soil to a depth of 75 cm increased water infiltration and resulted in increased crop yields, but did not significantly affect the crop relative yield-soil ECe relationship. From the results it is proposed that on the slowly permeable duplex soils, when watertable depth is controlled, management strategies for lucerne irrigated with saline water should be based on controlling the salinity of the shallow soil depths, to 60 cm.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 19 (1984), S. 3236-3248 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Over a wide range of frequencies, the a.c. conductivity of ionic materials shows two regions of frequency-dependent conductivity. These are each characterized by a term Kω p 1−n ω n where K, n are constants, ω p is a fundamental frequency identified with the hopping rate and ω is the measuring frequency. This behaviour is an example of Jonscher's Law of Dielectric Response for ionic conductors. In many cases, the region of low-frequency dispersion approximates to a frequency-independent plateau which may be taken as the d.c. conductivity. In others, a significant low-frequency dispersion is present and cannot be ignored in determining the effective d.c. conductivity. A method for the extraction of d.c. conductivities, hopping rates and for estimating carrier concentration effects is described. Data for three different types of material, single-crystal LiGaO2, β″-alumina and Na/Ag β-alumina are used to illustrate the method.
    Type of Medium: Electronic Resource
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