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The Global ETD Search service is a free service for researchers
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Showing 1 to 6 of 6 (0.035 seconds)Spelling suggestions: "subject:"soil surfaces"" "subject:"oil surfaces""
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Mulching Techniques for Arid Lands Vegetable ProductionPeebles, R. W., Oebker, Norman F. 23 April 1971 (has links)
From the Proceedings of the 1971 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 22-23, 1971, Tempe, Arizona / Mulches have been used for evaporation suppression in facilitating vegetable production under arid lands conditions. A study was undertaken in order to evaluate the effectiveness of plastic aprons, supplied by the FAO, as compared to gravel mulches. The vinyl aprons were 6 mils thick and about 1 meter square. Squash plants (Cucurbita pepo) were planted with gravel or plastic aprons or in bare areas and under different watering schedules. The yields under plastic aprons were considerably greater than under gravel and required slightly less water. Bare soil yields lagged far behind. Soil temperatures under the plastic aprons were consistently higher over 24 hours than bare soil, which within limits, would facilitate faster crop growth. Additionally, the apron collects and diverts rainfall to the plant. The vinyl used lasts only 2 seasons, and gravel would probably be a more suitable mulch for developing countries where capital is scarce.
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Assessing Soil Moisture RemotelyReginato, Robert J., Idso, Sherwood B., Jackson, Ray D. 12 April 1975 (has links)
From the Proceedings of the 1975 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 11-12, 1975, Tempe, Arizona / Space-age technology has produced tools which when turned to earthly pursuits can provide information on food and fiber production. Soil moisture has the potential for being remotely assessed, and three techniques for accomplishing this are under study. Two of the methods, reflectance and thermal, are sensitive to the conditions of the bare soil surface. The third technique, microwave emission, appears to have a good potential for assessing soil moisture with depth, because of its greater wavelength.
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A Microroughness Meter for Evaluating Rainwater InfiltrationSimanton, J. R., Dixon, R. M., McGowan, I. 15 April 1978 (has links)
From the Proceedings of the 1978 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 14-15, 1978, Flagstaff, Arizona / Described is a microroughness meter developed to obtain numerous and accurate measurements of rangeland surface microroughness and characteristics. The meter, which consists of four basic parts: (1) meter base and pin guide, (2) pin lifting support bar and lifting mechanism, (3) 100 vertically moving pins, and (4) stripchart support guide and winding mechanism, was designed to measure soil surface evaluations and characteristics of a 1m2 plot. Performance tests on multi-plot sprinkler infiltrometer studies conducted on the Santa Rita Experimental Range in southeastern Arizona indicated that the meter was accurate and relatively precise in repeating soil surface roughness measurements but was not precise in defining the theoretical characteristics of constructed surfaces. It was concluded, however, that these errors in precision were insignificant and due partly to surface geometry construction errors and that the meter is a convenient, quick, simple and accurate means of measuring surface roughness in studies requiring many plots and data points.
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Hydrologic Effects of Soil Surface Micro-FloraFaust, William F. 23 April 1971 (has links)
From the Proceedings of the 1971 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 22-23, 1971, Tempe, Arizona / Previous studies have indicated that blue-green algae may affect runoff, infiltration and erosion at soil surfaces. Using soil plots upon which blue-green algae were grown under an artificial wetting regime, studies were made using simulated rainfall. A 30% clay content Pima soil and a contrasting 8% clay content river-bottom anthony soil were used. Scytonema hoffmanii and Microcoleus vaginatus grew on the pima soil while Schizothrix calcicola developed on the Anthony soil. The results showed that blue-green algal growths significantly reduced the amount of suspended soil material in runoff water as compared with bare soils. Differences in runoff suspended sediments were also related to differences in soil type and simulated rainfall intensity. An analysis of variance of the effects of these 3 factors and their interactions showed that the smaller differences in suspended sediment production on the Anthony soil due to the microvegetation treatment was verified by a highly significant soils-microvegetation interaction, probably because the finer pima soils wash away more easily without stabilizing microvegetation. Also, less vegetation seems to grow on the Anthony soil. Differences in runoff and infiltration volumes and in settleable sediment amounts were not detected.
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Assessing Soil-Water Status Via Albedo MeasurementIdso, Sherwood B., Reginato, Robert J. 20 April 1974 (has links)
From the Proceedings of the 1974 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 19-20, 1974, Flagstaff, Arizona / Reliable information on soil-water status is required in order to make accurate water balance studies of watersheds, to determine the survival probabilities of various types of vegetation between rainfalls in low rainfall areas, and to determine the susceptibility of the uppermost soil to wind erosion. Simple solarimeters may help to accomplish this objective. Bare soil albedo was a linear function of the water content of a very thin surface layer of soil, and albedo correlated well with water contents of thicker soil layers. In addition, albedo measurements could be used to delineate the 3 classical stages of soil drying. Albedo may also be used to differentiate between the initial potential rate phase of evaporation following an application of water, and the succeeding falling rate phase. Results of applying this technique to a field of Avondale clay loam indicate that 20% to 25% of the water applied by either irrigation or rain will be lost by stage 1 potential evaporation, independent of seasonal variations in evaporative demand. Presently the techniques developed are applicable only to bare soil surfaces.
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Laboratory Evaluation of Water-Repellent Soils for Water HarvestingFink, Dwayne H. 20 April 1974 (has links)
From the Proceedings of the 1974 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 19-20, 1974, Flagstaff, Arizona / Reported are laboratory evaluations to screen water-repellent materials and treatments before testing them in the field. Water repellency tests were conducted on paraffin wax, a wax emulsion and silicon, lard, and a liquid dust suppressant. Six water repellency tests showed that the high rates of paraffin wax and all rates of the dust suppressant produced highly water-repellent soil surfaces. The six water repellency tests were: (1) the aqueous-alcohol drop test for determination of the 90 degree surface tension for a porous solid, (2) the water drop penetration time test, (3) the relative height of a large sessile water drop resting on the smoothed, treated soil surface, (4) and (5) the presence and persistence of air bubbles trapped between the soil-water interface, and test (6) was made to note whether the large sessile water drop from test (3) would infiltrate the soil or evaporate. Tests (3), (4), and (5) proved the most useful of the six methods for measuring water repellency. Soil type had no significant influence on degree of water repellency as measured in the laboratory by these six tests.
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