No description available.

The objective of this study was to determine whether the properties of four soils of the Silverbell Desert Biome could be attributed solely to the parent material or alternately reflect the nature of contributions, if any, from eolian dust. The Anklam, Lajitas and Chimenea soils, classified as fine-loamy, mixed, thermic Lithic Haplargids and the Greyeagle (coarse-loamy, mixed, thermic, Lithic Torriorthent) soil formed an andesite, basalt, granite and basalt, respectively. They occur on gently sloping, stable terrain in Pima County, Arizona. The four soils were studied through field descriptions, particle size analysis, mineralogical analyses of light and heavy sand fractions and clay mineral identification. The light mineral fraction of all four soils is directly affected by the parent material and is influenced much less, if at all by eolian activities due to the larger particle sizes. It is concluded that the genesis of soils was influenced by both the underlying rock and the input of eolian particulates. (Abstract shortened with permission of author.)

No description available.

The Marana Platform Mound Community (AZ AA:12:251[ASM]) in the Tucson Basin of southern Arizona provides a unique opportunity to examine the mechanisms of social organization within an early Classic Period Hohokam community. The role of the platform mound for integrative communal ritual or segregated elite-controlled activity is examined through faunal remains from the platform mound and nearby residential localities. Taxonomic diversity, relative abundance, and element distribution are used to measure the extent to which the platform mound served to integrate or distinguish site residents. Subtle differences in the diversity of taxa, the quantity of deposited faunal remains, and the quality of portions and taxa are indicative of differential access to resources between residents at the Platform Mound and residents in sites further away in the Tucson Basin. The findings support the current hypothesis that a dual mode of network and corporate strategy was used to organize the community.

No description available.

Declining infestations and the cyclic appearance of Phymatotrichum root rot of cotton from season to season led to the suggestion that antagonistic microorganisms were the cause of this phenomenon. This study was concerned primarily with Actinomycetes spp., fluorescent Pseudomonads, Trichoderma spp., and other fungi. There was a continuous fluctuation in the population of Actinomycetes spp. and fluorescent Pseudomonads on the surface of strands. Populations of these antagonistic organisms dropped as the viability of strands of P. omnivorum decline. Comparison of the rhizoplane microflora from infected and healthy roots showed no relationship between the populations of Actinomycetes spp. and fluorescent Pseudomonads and the resistance of healthy roots to invasion by P. omnivorum. Similarly, soil samples collected from areas with declining infestations and assayed for populations of Actinomycetes spp. and fluorescent Pseudomonads, revealed no differences in the populations of these antagonistic organisms. This indicates that the absence of the disease in areas with declining infestations is not due to the microorganisms investigated in this study. Higher mortality rates of strands of P. omnivorum occurred when strands were exposed to Actinomycetes spp. and fluorescent Pseudomonads or to their metabolites. The hyphal deformation observed on strands from the field could not be reproduced in vitro. The same antagonistic microorganisms sprayed on cotton roots containing strands failed to reduce strand viability.

No description available.

A study of soil variability was performed on an 87 hectare area within a uniform mapping unit--Pima Clay loam-- at The University of Arizona Branch Experiment Station at Marana. The primary interest was with respect to soilwater parameters. From 36 sites selected by an unbalanced three-stage nested design, 180 core samples were collected at 30 cm depth intervals to 150 cm. In addition, 500 bulk samples were taken at the 60 cm depth on an equally spaced grid over a secondary sampling area of 96 by 76 meters. The measured parameters showed different patterns of spatial variation. For example, to estimate means within 10% for the 30 cm depth 5, 51, and 1,011 samples would be needed for bulk density, the porosity index, and the saturated hydraulic conductivity, respectively (using the 0.05 level of significance). Most of the other estimates for number of samples required were in a range of 50 to 100. Most coefficients of variation were between 10 and 50% with bulk density lower and saturated hydraulic conductivity higher. Variance components for the three stages obtained from the analysis of variance revealed that the variation among fields was smaller than within fields and sections for the majority of the measured parameters, their average relative contribution to the total variance being 25, 44, and 31%, respectively. Values of 15-bar moisture retention corresponding to the 500 bulk samples showed a frequency distribution close to the normal with a slight tendency toward skewness. Values of bulk density were normally distributed at each depth and on the combined 180 samples. The highly skewed distributed values of the saturated hydraulic conductivity proved to be normally distributed after a logarithmic transformation. The porosity index showed a nonconsistent distribution pattern at the different depths and a moderately skewed frequency distribution for the composite 180 samples. Close relationships were found between bulk density and per cent sand and silt. A highly significant correlation (significant at th 0.01 level) between 15-bar water retention and clay content existed. Values of the logarithm of the hydraulic conductivity showed a high degree of correlation with values of per cent pores drained at 50 millibars (correlation coefficients of high absolute values and significant at the 0.01 level). Particle size distribution exhibited a decrease of silt and clay and a corresponding increase of sand with depth. The average percentages of sand, silt, and clay at 30 cm depth were 23.3, 41.2, and 35.3, and at the 150 cm depth were 39.7, 35.6, and 24.7, respectively. A similar trend was revealed for bulk density which ranged from 1.42 at 30 cm depth to 1.57 g/cm³ at the 150 cm depth. Soil moisture release curves for each depth showed similar general shapes. The "porosity index" describing the moisture release curve in the low pressure range varied from 3.58 at 30 cm depth to 5.79 at the 150 cm depth. Mean values of the saturated hydraulic conductivity also tended to increase with depth--1.71 and 7.03 cm/hr at 30 and 150 cm depth, respectively. Comparison between the sampling scheme used and three-stage balanced designs revealed that at least two alternatives would be more effective in decreasing the variance of the mean, but they do not provide any degrees of freedom for the third stage. An apparent compromise was found to exist between the scheme used and the optimum unbalanced designs selected for efficient estimation of variance components for the majority of the measured parameters.

No description available.

Differential adaptations of barley (Hordeum vulgare L.) and wheat (Triticum spp.) genotypes suggest that they be evaluated under multi-environmental conditions. The objectives of this study were to determine if small grain genotypes, bred for various moisture conditions, respond differently in terms of yield, water use, and rooting pattern to contrasting moisture conditions. Eight small grain genotypes were compared under a gradient of water from 89 to 404 mm (plus 254 mm of stored water) in a field study at Marana, AZ. A barley bred for low input conditions had greater root density in the subsoil and used moisture earlier in the season when compared to a high input barley (WestBred Gustoe). The cultivars bred for high input conditions required more water for optimum yield compared to those bred for low input conditions.