FAO/UNDP MEX 74/003 / Technical Report / Prepared for the International Conference on Managing Saline Water for Irrigation, Lubbock, Texas, U.S.A. August 16-20, 1976. / FAO of United Nations Project, UAAAN/FC / Buenavista, Saltillo, Coahuila, 1976. / Note: Item states For Internal Use only. Online copy not available. / INTRODUCTION: More than 52% cultivable area of Mexico is classified as arid and semi-arid. Nearly half of this area, particularly in the Northern States is extremely arid and presents with some salinity, alkalinity and water logging problems. Ground water, when available for irrigation, is often saline or moderately saline-sodic. The soils of this region are calcareous and contain some salts and sodium. Soils also contain sub-surface horizon rich in carbonate and compact in nature, which may be 30-90 cms below the ground surface. Before planning a major irrigation system for crop production, provision of drainage and leaching of salts is often recommended for this region. The good quality water from underground source may rarely be available for leaching salts and when available pumping costs are prohibitively expensive. It has also been pointed out in the past that such lands could be used to harvest water. In fact, rudimentary water harvesting systems have been established by local people in some parts of this area. Thus, with the need for integral land use and water reclamation in mind, a multipurpose water use and water harvesting system was developed. The requirements of this system, among others, are: (1) To collect enough water for multiple use inside or outside the system, (2) To increase the desired production of the marginal saline land within the system, and, (3) To provide an economically feasible long term farming system for the low-income community. Such system is under development at the Ejido San Francisco del Barrial, near Parras in the State of Coahuila.

For presentation at the International Symposium on Brackish Water as a Factor in Development, by the Desert Research Institute at Sede-Boqer at the Ben-Gurion University of the Negev, Beer-Sheva, Israel, January 5-10, 1975. / Introduction: The Safford Valley area lies along the Gila River in the southeastern part of the State of Arizona. The portion of the valley being considered, see Figure 1, is an intermontane trough averaging about 15 miles (24.2 kilometers) in width and about 30 miles (48.3 kilometers) in length. The cultivated lands lie along the Gila River and are 0.5 to 3.5 miles (0.8 to 5.6 kilometers) from the river. The approximately 14,000 inhabitants of the valley are primarily located in the municipalities, and Safford, the largest of the towns, was founded in 1875. Agriculture and agriculture-dependent activities, however, provide the mainstay of the Safford Valley economy accounting for approximately 63 percent of the export employment (State of Arizona, 1971). Like many valleys in arid regions, the Safford Valley, because of an inadequate supply of good quality water, has been forced to depend on ground water of notoriously poor quality. The purpose of this paper is to show how the limitation of available good quality water and the need to use brackish water affects agricultural practices and industrial development in the Safford Valley.

No description available.

Sustainable Built Environments Senior Capstone / This paper will look at the current information concerning sustainable strategies. It will look at the ones that have been used in the past as well as the strategies that are currently being used. After studying the existing material on sustainable practices and strategies the next step will be looking at three primary sources and determining strategies that will be most useful. The first source that will be used is a professional working in the field. Secondly buildings that are located in a cold arid climate will be studied and finally a program called climate consultant. The recommendations from all three sources will be compiled in a list, organized by how many sources recommended each strategy. The strategies that have the most recommendations will be implemented into a residential single family building design for cold arid climates.

<p>Tortoises appear to be successful in arid ecosystems, where they depend on primary production for their predominantly herbivorous diets. The low primary production of arid regions is exacerbated by priodic droughts, so that iteroparous species such as chelonians require mechanisms to overcome resource shortages. The smallest of all tortoises, Homopus signatus signatus, occurs in a dry winter rainfall area in northwestern South Africa that is threatened with aridification due to regional climate change. The overall aim of this study is to understand the ecology of H. s. signatus, particularly in reference to the importance of rainfall.</p>

Common heliotrope (Heliotropium europaeum L.) is an herbaceous Mediterranean summer annual that grows on areas devoid of vegetation in the dry-land cropping region located in the north-west of the state of Victoria, Australia. This region is known as the Mallee, and common heliotrope is considered a weed here because it transpires soil water that could otherwise be used by ensuing crops, and is toxic to livestock. / In this study, laboratory experiments have shown that germination of seeds of common heliotrope is not limited by light, cold treatment, or a leacheable inhibitor. Temperature and water potential (and perhaps depth inhibition) are the principal environmental factors that limit germination. Although 100 % of seeds will germinate under optimal conditions, these conditions are rarely met in the field, and the percentage of seeds that germinate at sub-optimal conditions changes seasonally and between Australian populations. This is the principal mechanism of dormancy in the species, ensuring that seeds do not germinate when conditions are unfavourable for continued growth and that in the field, germination of a seed population is fractional, spreading risk temporally. Germination of seeds of common heliotrope does not conform to the assumptions of the hydrothermal time model frequently used to predict field emergence of weed species. / Field observations and simulated rainfall experiments on a consistent soil type (Calcarosol with a clay loam surface texture and clay subsoil) indicated that approximately 20 mm of rainfall is the minimum amount required for germination and emergence of common heliotrope. Field experiments using lysimeters indicated that this is also the amount required for minimal reproduction on the same soil type. Although common heliotrope can successfully reproduce upon the rainfall event which causes its germination, its growth is indeterminate, and further access to moisture will result in massively increased reproductive output. Plants will continue to grow and produce seed over summer until they are killed by drought or senesce in autumn. Laboratory and field studies showed that root growth in common heliotrope is relatively slow, and is opportunistic in areas where moisture becomes available. / Simulation of soil water and temperature fluxes showed that soil type has a large impact on the amount and duration of water potential that seeds and plants are exposed to. In the case of common heliotrope, this is critical in determining regional prevalence and distribution in the north-west of Victoria. It is recommended that studies of arid species reliant on isolated rainfall events for emergence should consider absolute water availability and not in terms of rainfall amount alone. / Analysis of long term summer rainfall data from the Victorian Mallee indicates that there is potential for reducing the cost of controlling common heliotrope by using residual pre-emergent sulfonylurea or triazine herbicides, instead of the traditional post-emergent herbicides or cultivation. More information is needed on the efficacy of such residual herbicides on common heliotrope and other summer weeds, and their impact on subsequent crops before the full potential of this management option is known. Reduced cost of control could also be achieved by economic analysis of the likely benefits of controlling each emerging cohort of common heliotrope, and a framework for decision making is suggested.

"June 2002" / Bibliography: leaves 172-198. / viii, 198 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Proposes that the overall outcome of plant interactions along a temporal gradient of resource availability changes from positive during interpulses to negative during pulses. Examines negative interactions between 4 co-dominant chenopod scrubs in arid Acacia papyrocarpa woodlands. Negative interactions were more intense when conditions were least productive. Positive interactions between seedlings also changed over time, depending on the facilitation mechanism. Plant interactions seem to be most intense at the beginning of interpulses when plants are competing for diminishing water, or survivorship is enhanced in the favorable microsites provided by other plants. Later in the interpulse, interactions become less intense as conditions become more stressful and therefore survivorship and growth are affected more by abiotic conditions than plant interactions. / Thesis (Ph.D.)--University of Adelaide, Dept. of Environmental Biology, 2002

Bibliography: leaves 155-169. / xiv, 169 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Studies the effect of nitrogen fertilizer on dry matter production under differing watering regimes. Investigates the accuracy of different crop and soil organic matter models for predicting crop yield, nitrogen uptake and changes in soil organic carbon and nitrogen. Compares the models with data from long-term field experiments on wheat in Australia and sorghum in Ethiopia. Finds that a higher crop yield and better nitrogen and water utilisation can be achieved if addition of nitrogen fertilizer is balanced with soil water. / Thesis (Ph.D.)--University of Adelaide, Dept. of Agronomy & Farming Systems, 1997?

Thesis (Ph. D. - Soil and Water Science)--University of Arizona, 1986. / Includes bibliographical references (leaves 170-184).

Thesis (M.S. - Renewable Natural Resources)--University of Arizona, 1985. / Includes bibliographical references (leaves 64-69).