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  • 1
    Electronic Resource
    Electronic Resource
    IMPROVING IRRIGATION WATER MANAGEMENT IN THE INDUS BASIN (1979)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 15 (1979), S. 0 
    Details
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : Over half of the water delivered from the canal system to the watercourses managed by the farmers is not made available to the farmers' crops in Pakistan. Most of this water loss is due to loss of water through the banks of the watercourses. Lack of maintaining these banks and lack of cleaning the watercourse is a result of inadequate organization of the 10 to 150 farmers who use the watercourse, and a deficiency of knowledge concerning the amount of their water which is being lost.Various methods of watercourse improvement have been evaluated including concrete and masonry linings and simple earthen improvements of the ditches with concrete control structures, junctions, and turnouts. With the cost of labor low in Pakistan, the earthen improvements with concrete structures appear to be the best investment.Farm water management improvement programs have been implemented in most of the provinces which include this type of watercourse improvement, land leveling and advice to the farmers on how and when to irrigate his crops to optimize his production.The rate at which personnel can be trained to help the farmers implement these improved water management practices is limiting the rate of implementation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1752-1688.1979.tb00349.x
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  • 2
    Electronic Resource
    Electronic Resource
    MELTING TEMPERATURES OF COMPOUNDS ADSORBED ON SILICA GEL1 (1938)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 42 (1938), S. 369-380 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100898a006
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  • 3
    Electronic Resource
    Electronic Resource
    THE EFFECT OF SURFACE FORCES ON MELTING1 (1938)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 42 (1938), S. 381-390 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100898a007
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  • 4
    Electronic Resource
    Electronic Resource
    High activity of choline acetyltransferase induced in neuroblastoma X glia hybrid cells
    Amsterdam : Elsevier
    Experimental Cell Research 85 (1974), S. 399-408 
    Details
    ISSN: 0014-4827
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0014-4827(74)90142-6
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of drying on soil strength and corn emergence (1985)
    Springer
    Irrigation science 6 (1985), S. 149-158 
    Details
    ISSN: 1432-1319
    Keywords: corn emergence ; soil strength ; modulus of rupture ; soil water content ; water and soil surface treatments ; bare and mulched soil surfaces
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Laboratory studies were conducted to evaluate the effects of drying on soil strength and corn emergence (Zea mays L.). Corn was germinated in Billings silty clay under a bank of heat lamps which operated 9, 14, 19, or 24 h per day. Soil strength (modules of rupture), soil moisture content and emergence were measured daily. The relationship of soil strength to corn seedling emergence as influenced by the four light and heat durations and bare and mulched soil surfaces was determined. As soil strength increased emergence decreased until it ceased at soil strengths of about 80 kPa. Strength of this soil had a high negative correlation with soil water content and increased with time. Mulching decreased initial rate of drying, decreased crust strength, and improved corn emergence. The 14-hour light and heat treatment resulted in the highest corn emergence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00572663
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of soil properties on precipitation use efficiency (1993)
    Springer
    Irrigation science 14 (1993), S. 65-73 
    Details
    ISSN: 1432-1319
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract As other non-agricultural users need and are able to pay higher prices for irrigation waters it will be increasingly essential to make more efficient use of precipitation in crop production. Major problems constraining the efficiency with which rainfall is used are: large portions of this water run off or are evaporated from soil surfaces; root zone water holding capacity is not sufficient to hold water needed to sustain good crop production; and the random nature of the precipitation and associated probabilities of crop failure deter investments needed to achieve improved efficiency of water use on high value crops in rain fed lands. Gravel and organic mulches have shown potential for reducing annual evaporation to as low as 10 cm of water and for facilitating entry of expected intensities of rainfall. Under such mulches, soil water is almost as dependable as “money in the bank”, and can be retained for use in seasons when high value crops are most efficiently grown. Measurements of such stored water plus past weather records can provide bases for calculating probabilities of adequate water being available for crops whose water requirements are known. Most of these water requirements have been determined when these crops were planted close together and root zones, and in some cases the crop canopy, overlapped. Research is needed to determine the degree to which wider spacing of high value vegetables and fruit crops under mulched conditions can be used to increase probabilities of economic production when water supplies are marginal. For tree crops, where planting density is not temporally flexible, but small amounts of irrigation water may be available at high cost, management systems are needed to optimize use of rain and ascertain when the economic benefits are sufficiently great to justify use of the irrigation water. Such sporadic use requires that the supply system can provide water on demand. Increases in rooting depths by modifying soils with restricting layers can serve as a cost effective alternative to irrigation under some climatic regimes. Such regimes should be identified and costs of increasing rooting depths should be evaluated and reduced where possible. Availability of municipal and industrial waste products, whose producers may be willing to pay costs of transport and incorporation, may provide economically feasible means of removing such restrictions. Production levels and environmental consequences of incorporating such wastes-cum-amendments in soils need evaluation to provide bases for developing optimized and acceptable management systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00208399
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  • 7
    Electronic Resource
    Electronic Resource
    Surface films affecting velocity profiles of slowly moving water in open channels (1984)
    Springer
    Irrigation science 5 (1984), S. 235-250 
    Details
    ISSN: 1432-1319
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Rates of movement of surface films and underlying water were measured using observable solid and liquid tracers. Water flow rate, surface width, water depth, and channel length were varied in flumes in which the water was allowed to flow over a broad weir crest at the tail end. In some runs the surface was blocked 5 cm in front of the weir. When this was done, velocity of the surface film immediately upstream from the block decreased to a small fraction of its previous value and this area of slow surface velocity built upstream with time, extending to as far as several meters under steady state conditions. In this reach, the film at the air-water interface of the water causes drag on the moving water similar to that at a solid-water interface. Water surface in channels one cm wide and 100 cm long stopped moving when the shear force caused by water flowing beneath it dropped to less than 0.0013 dynes/cm2. This indicates structure in the surface which does not deform or shear at rates proportional to the force applied. Average water flow velocities from 0.3 to 1 cm per second provided shear stresses in excess of 0.002 dynes/cm2 and moved these surface films. However, the velocity distribution across the surface of the channel was not parabolic, and indicated that most of the shear in the film was taking place near the edges of the channel. Extrapolation of these observations to water film dimensions present in unsaturated soils indicates that air-water interfaces in unsaturated soils are usually static.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00258177
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  • 8
    Electronic Resource
    Electronic Resource
    Sediment, erosion and water intake in furrows (1988)
    Springer
    Irrigation science 9 (1988), S. 45-55 
    Details
    ISSN: 1432-1319
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Observations and studies were conducted on the origin and destination of sediment in irrigation water, and the effects of sediment adsorbed on the wetted perimeter of furrows on water intake and erosion. Fine sediment adsorbed on the perimeter reduced intake and increased soil water tension which was the primary mechanism holding the sediment on the perimeter. This self enhancing effect causes this thin seal to decrease erosion and intake rates. In contrast, removal of a few square centimeters of this seal by chance events after water velocities and shear forces have increased often causes reduced tensions, exfoliation of the surface seal and erosion pits which develop into head cuts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00292142
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  • 9
    Electronic Resource
    Electronic Resource
    Soil management to prevent earthworms from riddling irrigation ditch banks (1988)
    Springer
    Irrigation science 9 (1988), S. 79-87 
    Details
    ISSN: 1432-1319
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Earthworm activities were observed under subdued light in lucite fronted soil filled boxes in which bean plants were growing. They formed their burrows by ingesting a relatively small core of soil about 2 mm in diameter and expanding these holes to a diameter of about 5 mm by flexing their muscles. The compacted zone extended about 4 mm from the radii of these burrows. As shallow bean roots of young plants extracted water from the upper portions of the soil, worms moved downward to moister soil. During furrow irrigation, worms moved toward the water source through existing burrows. A few of them burrowed new holes to the furrow and emerged and swam in the water for up to 20 min before burrowing back into the mud in the bottom of the furrow. In columns with sections packed with pressures of 50, 100, 200, 300 and 600 kPa, worm burrowing was reduced in sections packed at higher pressures and was practically negligible in the sections packed at 600 kPa. Visual comparison of porosity in the compacted soil surrounding earthworm burrows and the soil compacted at 300 and 600 kPa indicated that the worms are able to compact soil with a force between 300 and 600 kPa. Worms were not able to survive long enough to burrow through 15 cm of a subsoil with organic carbon content less than 0.2% that lay between them and topsoil. Both compaction and use of subsoil for the banks show promise for reducing earthworm burrowing and water loss from ditches.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00262352
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  • 10
    Electronic Resource
    Electronic Resource
    Book reviews (1987)
    Springer
    Irrigation science 8 (1987), S. 301-302 
    Details
    ISSN: 1432-1319
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00257513
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