No description available.

Pepper -- Arizona

The world supply of quality water for irrigation of crops is being depleted. Growers in the arid and semi-arid regions of the world, where irrigation is a requirement for crop production, are looking for ways to conserve their water use and increase their irrigation efficiency. One tool that has been useful in helping growers reduce their irrigation water inputs is computerized irrigation scheduling programs. This study is part of a joint project between the government of Egypt (National Agricultural Research Project), USA1D and The University of Arizona. Working together, researchers from Egypt and Arizona are developing water management tools that will help both countries better use their scarce water resources in arid environments. The main thrust of this segment of the project is to develop water use data on vegetables grown in both regions. These data will then be used to develop crop coefficient data to be used in AZSCHED, a computerized irrigation scheduling program developed at the University of Arizona. Using a subsurface drip irrigation (SDI) system, carrots, cauliflower, head lettuce, and tomatoes were grown to determine water use patterns and develop basal crop coefficients. Water use data were collected using a neutron moisture gauge and a time domain reflectometer (TDR). Soil water data were collected 1 day following an irrigation and just prior to the next irrigation. Additionally, three different watering regimens were employed using available water content in the rootzone as a trigger to initiate irrigation (20 %, 30% and 40% depletion). The carrots, cauliflower and lettuce were planted in early October, 1993, using a randomized block design. Yield data showed no significant differences between treatments for any of the vegetables. Also, the soil moisture data did not indicate water stress in the treatments. In March of 1994, tomato transplants were planted and the irrigation treatments were altered to 30 %, 40% and 50% depletion, in an attempt to get significant differences between treatments. The results for all four vegetables showed high variability in soil water data between replications, although an initial determination of basal crop coefficients was possible. Additional data will be required to better refine the crop coefficients.

Five different crops were evaluated in exploratory and observational field studies for potential use as a summer cover crop in a rotation with commonly grown vegetable and field crops. Sesbania ( Sesbania exaltata), cowpea (ViRna unguiculata), sunnhemp (Crotalaria iuncea var. Tropic Sun), sudangrass (Sorghum sudanense cv. Piper), and kenaf (Hibiscus cannabinus) were drill seeded and grown with 2-3 irrigations during the summer months in two field tests. In one test, fresh weight yields were: 7,794 lb/A for sesbania; 10,551 lb/A for sunnhemp; 5,184 lb/A for cowpea; 19,816 lb/A for sudangrass; and 2,390 lb/A for kenaf General observations indicated that adult whiteflies were attracted to sunnhemp at one test site but not at the other. Broccoli, cabbage, and barley were planted in the fall following the cover crops and general observations indicated that sudangrass significantly reduced all of the crops' stand and measurable responses were not evident where the other cover crops were planted.

The biotite + muscovite ± garnet-bearing Texas Canyon (TC), Presumido Peak (PP), and Gunnery Range (GR) granites are members of an enigmatic suite of Eocene age granites in southern Arizona. The late orogenic granites intrude Precambrian through Jurassic metasediments and metavolcanics. The major and minor element geochemistry of the high silica, weakly peraluminous granites is rather uniform. However, trace element concentrations, REE patterns, and isotopic compositions imply gross similarities between the TC and GR granites when both are compared to the PP granite. The TC and GR granites were derived from a depleted Precambrian lower crustal source area with low Rb/Sr, while the PP granite was the result of anatectic melting of an enriched Precambrian mid-to-upper crustal source. The PP granite is an integral part of a metamorphic core complex, and this tectonic setting accounts for the geochemical differences between it and both the TC and GR granites.

No description available.

Geophysical investigations were conducted at the proposed Maricopa SSC site in support of the geotechnical program for the State of Arizona site proposal. Modeling of a gravity survey across Rainbow Valley showed that the minimum depth to bedrock in the center of this basin is 750 meters (2500 feet). Gravity and magnetic surveys in Maricopa Valley between the north and south Maricopa Mountains indicated the possible presence of faults and diabase dikes. Seismic refraction surveys in the area of the proposed Injector Ring complex indicated a buried bedrock ridge about 400 meters (1300 feet) wide and approximately 25 meters (80 feet) below the surface. Geophysical surveys were also conducted at the Twin Buttes Mine near the proposed Sierrita SSC site. These surveys included gravity, seismic refraction, seismic reflection, DC resistivity and IP, and CSAMT surveys. Since the geology and geotechnical properties at the Twin Buttes mine are very well documented from extensive drilling, these surveys provide a calibration of observed geophysical signatures over various rock types.

Geophysical surveys were conducted in the Pima mining district by students from the University of Arizona. The surveys were concentrated along section B-B' from Cooper (1973). The objectives of this survey included: teaching geophysical techniques, mapping regional structure along this profile, and determining which geophysical techniques were most useful for regional .mapping in this area. Controlled source audio-frequency magnetotelluric (CSAMT) surveys successfully mapped depth to basement along this profile. Seismic refraction surveys were not able to map depth to basement. Either the depth to basement was beyond the range of the arrays used in this experiment or there is insufficient contrast in the velocity between the basement and the overlying rocks. A test of the seismic reflection method was carried out using a walk-away noise spread. Possible reflections from basement were noted but were not sufficiently diagnostic to be routinely use able.

No description available.

No description available.