Cordell, Susan Chapman. (The University of Arizona., 1994)
A field experiment was conducted for the purpose of analyzing the movement of water fronts and NO3-N leaching. A four-acre irrigated cotton field was divided into 12 sections with 2 plots in each. Each section represented a unit in an randomized complete block design, using two N treatments, two irrigation treatments and two samples sites. Cl⁻ and Br were used as conservative tracers to measure depth of water movement. At the conclusion of the growing season, twenty-four 10 ft. soil cores were removed from the field and analyzed for concentrations of NO3-N, Cl⁻ and Br⁻. Correlations existed between 15-bar water-holding capacity and chloride concentrations. The depth of the bromide front was significantly greater (p<5%) for the 70% irrigation efficiency than for the 90% efficiency. The concentration of nitrate-N below 5 feet was significantly lower for the 70% efficiency than for the 90% efficiency.
Janat, Mussaddak,1953- (The University of Arizona., 1985)
The effect of phosphorus (P) fertilization on drip irrigated cotton (Gossypium hirsutum L.) was studied in 1984 on a Trix clay loam classified as fine-loamy, (calcareous), hyperthermic, Typic Torrifluevent. The objectives of this study were to relate P fertilization to the P concentration in plant tissues, P uptake and cotton yield under drip irrigated conditions. Growth analysis data and total phosphorus in plant tissues were obtained at specific sampling intervals from both P and non-P fertilization treatments in a replicated field study. Moreover, flowering pattern, flower abscission and boll production were studied. Fertilizer treatments were arranged in a Randomized Complete Block design with N, NP, NPK and NPKZn treatments. Rates of N, P, K and Zn fertilizers were 175.4, 44.8, 88.6 and 2.58 kg/ha, respectively. Application of P in this field experiment did not increase P content in plant tissues and did not increase dry matter production, P uptake, and cotton yield significantly, but there were consistant trends toward increased dry matter, P uptake, and cotton yield in the P treated plots. Soil test for P before application of P fertilizer showed enough phosphorus was available in that particular soil for cotton production.
Zhou, Maoqian, 1961- (The University of Arizona., 1989)
The growth and Nitrogen fixation by one low salt tolerant alfalfa (Medicago sativa L.) and two germination salt tolerant selections inoculated with were investigated at two salt levels (0, -0.6 Mpa) and two N rates (1, 5ppm) using a system which automatically recirculates a nutrient solution. The high level of salinity (-0.6 Mpa osmotic potential of culture solution) resulted in substantial reduction in the N fixation percentage and total fixed N. The effect of salinity was more pronounced for later cuttings than for the earlier cutting. The N fixation percentages were substantially decreased by increasing N level and the reduction was enhanced by time. The N treatment levels did not exhibit a significant effect on total fixed N. Cultivars did not differ in either growth or N fixation. However, the interaction of N and salinity significantly decreased the percentage and amount of N fixation.
Levine, Steven Joel. (The University of Arizona., 1985)
Two soils, both underlain by petrocalcic horizons at shallow depths, occur together on the same geomorphic surface, an old fan terrace located in the Avra Valley near Tucson, Arizona. Both soils have formed from similar parent materials and are assumed to be of the same age. One of the soils, a Petrocalcic Paleargid, occupies the broad, flat interfluvial areas of the fan surface. It contains an argillic horizon above the hardpan and is carbonate free in the upper part. The lower portion of the argillic horizon has been engulfed by the petrocalcic horizon. The other soil, a Typic Paleorthid, occurs above and adjacent to the narrow drainage ways that incise the fan terrace. This soil lacks an argillic horizon and is calcareous to the soil surface. Although no direct evidence of a former argillic horizon remains, it is believed that an argillic horizon was once present and then was truncated. Truncation was followed by brecciation of the exposed pan surface and subsequent recementation. The observed differences between the two soils: calcium carbonate content, particle size distribution, color, morphology and size of calcite crystals, and clay mineralogy are a result of the pedogenic processes of argillic horizon engulfment and truncation followed by brecciation and recementation.
Turk, Colleen Mary, 1961- (The University of Arizona., 1995)
Organic matter amendments have long been known to improve native organic matter content, aggregation and structure of soils. In the laboratory, however, organic matter amendments to autoclaved soils have no such effect. This may explain the failure of many reclamation attempts on mine tailing wastes, which often proceed without regard for the microbiological processes necessary for soil formation and cycling of plant nutrients. In this study, incubation of tailing waste with soil microbes and a simple carbon source proved sufficient to increase the formation of water stable aggregates from tailing particles. Autoclaved control samples showed no change in aggregation. The incorporation of microbial cell mass into the mineral matrix of the tailing was observed using scanning electron microscopy. These results suggest that microbial activity is necessary in order to incorporate organic matter into the abiotic matrix of tailing, promoting aggregation and ultimately soil formation from this material.
Qi, Jiaguo, 1959- (The University of Arizona., 1989)
An experiment was conducted to determine whether the water depth (above soil) and soil type would have any influence on the multispectral reflectances of paddy rice, and their calculated vegetation index values. The results showed that, when vegetation cover was low (below 600 grams of dry biomass per square meter), the near infrared (NIR) reflectances decreased very little with water depth. The same was true for red reflectances, but to a lesser degree. Overall the changes were not significant at 0.05 level of significance when the water depth was increased from 2.5 centimeters to 10 centimeters. When the vegetation cover became higher most NIR and red reflectances did not show a significant decrease with the increase of the water depth, and sometimes they even increased slightly up to a water depth of 6.4 cm. Nevertheless both rice cover and water depth as well as soils played an important role in the reflectance pattern in red and NIR bands. Some index values increased and some decreased depending on water depth and rice cover. Statistical analysis of the data showed that rice multispectral responses were mainly controlled by vegetation and minimally influenced by soil and water depths.
Neilson, Julia Killian Worsley,1958- (The University of Arizona., 1988)
The use of liquid sewage sludge on agricultural soils may improve productivity, but cause compaction due to an application procedure requiring multiple passes with heavy machinery. The movement of water through the soil profiles was used as an index indicating a greater degree of compaction in soils amended with high amounts of sewage sludge vs. low amounts or inorganic fertilizer. Laboratory studies developed a method to utilize CO 2 evolution from microbial respiration as an index of soil aeration. Samples of Pima clay loam soil of varying moisture levels were amended with inorganic fertilizer or sewage sludge and compacted to several bulk densities. Aeration restricted microbial respiration at 1.6 Mg m-3 bulk density and 0.24 g g -1 , and 1.4 Mg m -3 bulk density and 0.26 g g -1 moisture, with no variation due to soil amendments. Respiration rates increased in a compacted sewage sludge amended soil, after an incubation period, indicating an improvement in soil structure due to the sludge.
Galioto, Thomas Robert. (The University of Arizona., 1985)
An elevational study of organic matter components was made of shallow soils of the Santa Catalina Mountains, Pima county, Arizona. At nineteen elevations (900 to 2700 m), total carbon, extractable organic carbon, humin carbon (tightly bound organic carbon), humic acid carbon, fulvic acid carbon, humic-fulvic acid ratios and E4/E6 ratios were determined. Parameters except the humic-fulvic acid ratios showed high correlations, R² at least .78, with elevation. Of these only the E4/E6 ratio was negatively correlated with elevation. Uncorrelated humic-fulvic acid ratios indicate no proprotional trend of the relative proportions of humic and fulvic acids. The E4/E6 ratio decrease with elevation agreed with all parameters. Humic acids are older, larger and contain higher concentrations of aromatics with increasing elevation. The humic-fulvic acid ratio, based on classical organic matter separation, does not produce a discriptively useful means for a range of climatically different soils. The E4/E6 ratio is more useful in evaluating soil genesis via composition.
Guilbault, Michael Roland, 1967- (The University of Arizona., 1993)
This study was conducted to determine emission rates of nitrous oxide (N₂O) gas from arid region locations. Fluxes were measured at an effluent-irrigated turfgrass location in Arizona, a Sonoran desert location, and a savannah location in Africa. Fluxes were measured by a closed chamber method at the Arizona locations on a weekly basis during the summer of 1991, and at the African location during two separate three day studies during the summer of 1992. Soils were sampled at each location during each sampling period and analyzed for water content, nitrate, pH, and total organic carbon content. Nitrous oxide fluxes in Arizona averaged approximately 13 and 0.7 kg N₂O-N ha⁻¹ yr⁻¹ for the turfgrass and desert locations respectively. The average fluxes from the African sites were 1.3, 1.6, and 1.3 kg N₂O-N ha⁻¹ yr⁻¹ for a millet field, fallow field, and "tigerbush" plateau, respectively. Diurnal and seasonal variability was observed.
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