Reclamation of four salt-affected soils collected from southern Arizona was studied in the greenhouse and laboratory. Two rates of four amendments (sulphuric acid, gypsum, ammonium polysulphide, and ammonium thiosulphate) were applied in triplicate. Results were evaluated in terms of changes in nutrient availability, ions removed by leaching, plant growth, and infiltration rates. In most cases the high rates of sulphuric acid and gypsum increased the solubility of the major cations (Na, K, Ca, and Mg) in the soil. If the required amount of leaching water were applied to the soil, a significant amount of these cations, especially Na, was leached from the soil. For the Gothard soil (saline-sodic) two pore volumes were sufficient to accomplish leaching, but were insuffcient for the Guest (nonsaline-slightly sodic) and Gilman (highly saline-sodic) soils. High rates of sulphuric acid and gypsum decreased the pH and increased the EC for all soils, although the EC was not significant at the 5% level for the Mohall (nonsaline-nonsodic, calcareous) soil. All treatments decreased the pH of the Gothard soil significantly; however, the greatest increase in EC and least pH were obtained from acid application. Regarding changes in phosphorus (P), all treatments increased the amount of soluble P in the leachates from the Gothard and Guest soils; whereas available soil P increased significantly only with the acid treatments. None of the treatments affected the amount of P in the Gilman soil leachates, but acid and gypsum increased the available soil P. Ammonium polysulphide and ammonium thiosulphate tended to increase available P but the increase was not significant at the 5% level. None of the treatments affected the P parameters for the Mohall soil. Sulphuric acid increased growth and P uptake of alfalfa plants on all soils except the Mohall. Gypsum and ammonium polysulphide increased P uptake on the Gothard and Guest soils whereas ammonium thiosulphate increased P uptake only for the Guest soil. Sulphuric acid and gypsum increased the infiltration rates for all four soils. Thiosulphate produced intermediate infiltration rates while the lowest rates were found with ammonium polysulphide and the untreated soils. Although amendment rates were based on equivalent amounts of sulphur and their effectiveness in supplying soluble calcium, and the exchangeable sodium status of each soil, results varied according to such factors as rate of oxidation of the amendment, lime content of the soil, soluble salts present in the soil, and soil texture.

A field study was conducted to determine water and salt distribution patterns in a soil irrigated by pairs of double-chamber, perforated polyethylene tubes. The study consisted of two experiments: a water distribution experiment and a salt distribution experiment. Both experiments were conducted at the same site with experimental plots having two perforated lines 9 m long, spaced 0.60 m. The tubing had outer orifices 0.5 mm in diameter spaced 0.30 m along the tubes. The water distribution experiment consisted of water application to the bare soil for periods of time of 3, 6, 9, and 12 hours. After each test a trench was dug normal to the irrigation tubes and samples were taken to determine soil moisture on a dry weight basis. Moisture profiles are presented for the various tests. The salt distribution experiment was conducted in the Fall of 1973 and repeated in the Spring of 1974. It consisted of four irrigation treatments comprising two irrigation levels and two levels of salt in the irrigation water (327 and 2000 milligrams per liter of salts). Experimental plots were planted with lettuce and soil samples taken after planting and after harvesting the lettuce. Soil samples were analyzed for electrical conductivity of the soil saturation extract, pH, calcium, magnesium, sodium, potassium and nitrates. Saturation extract conductivity profiles in the soil are presented for different treatments. After planting and after harvest concentrations of calcium, magnesium, sodium, potassium, nitrates and pH values are also shown. Seasonal water application and lettuce yields are presented for both trials Water movement in the soil was 2 to 3 times greater in the horizontal than in the vertical direction. Wetted soil volume showed a high positive correlation with both the volume of water applied and with time of application. Salt accumulation occurred mainly at the soil surface between the irrigation tubes and away from the main root zone of the plants. The surface accumulation was followed by a leached zone. There were no significant differences in yield among plots receiving different treatments. Seasonal water application was less than half of the seasonal amount of water normally applied for furrow irrigated lettuce in the Tucson area. It was higher than experimental determinations of seasonal consumptive use for lettuce at Mesa, Arizona. The study indicated that trickle irrigation with water of high salt content is likely to cause a high surface concentration of salts. Application of extra amounts of water by the trickle system, or another method, is recommended to leach the salts to a depth below the crop root zone.

The general purpose of this research was to determine the effects of paper-pulp mill wastewater disposal on the quality of the soil, . vegetation, groundwater, and environment in north central Arizona. Analytical laboratory procedures were used to determine the physical, chemical, and biological properties of the soil, vegetation, and water samples. Analysis of Variance was computed on soil, water, and plant analytical data to determine the significance of; downward distribution of wastewater constituents in clay soils under natural environment and ponded conditions; the heavy metal contents of natural and ponded vegetation in the area; and any changes in the environments surrounding and water sources due to disposals for the past 23 years. There was very slight movement of paper-pulp mill wastewater constituents into the clay soil below the disposal basin. Vegetation was not altered by irrigation with SWFI paper-pulp mill wastewater, either with respect to heavy, trace, or common ions or growth responses.

The effect of 80- and 90-inch wide-bed cultural practice systems and alternate furrow irrigation on soil moisture distribution, water use and yields of cotton were studied as compared to every furrow irrigation of conventional 40-inch rows. The every furrow irrigation treatment had the highest soil moisture content throughout the season and received the most water. Alternate furrow irrigation treatments had the lowest soil moisture content and received about 30 percent less water than the every furrow irrigation treatment. There was limited soil water movement from the irrigated furrow to the adjacent non-irrigated furrow. The 90-inch beds had higher soil moisture contents than the 80-inch beds, with about equal depths of water applied. There was considerable lateral movement of water toward the bed center. The wide beds received about the same quantity of water as the alternate furrow irrigation treatment. No significant difference was found in seed or lint cotton yields due to row spacing or alternate furrow irrigation. The wide-bed cultural practice and alternate furrow irrigation systems had similar water use efficiencies, expressed as lint yield per inch of applied water. These systems increased the water use efficiency about 23 percent over the every furrow irrigation system.

The canal side weir system is a relatively new method for water distribution to irrigation furrows. The system consists of a concrete lined ditch (canal), equipped with small openings or weirs which deliver the design irrigation flow rate into individual furrows. This research aims at evaluating the proformance characteristics of this system through laboratory, field, and computer studies. A laboratory model was used to establish head discharge relationships for various weirs at different channel velocities. For sharp entranced weirs, discharge for a given head was found to be inverselly proportional to the magnitude of the channel velocity. At small heads (20-30 mm), discharge at 0.3 m/s velocity was found to be about 15% less than the corresponding discharge at zero channel velocity . For normal irrigation settings (head on the weir = 60-80 mm), the difference was about 6%. Streamline entranced weirs were found to have negligible sensitivity to changes in the channel velocity. Field evaluation studies revealed better overall proformance than conventional systems. For an operating system, an application efficiency of 86% with uniformity coefficient of 0.84 at 7% deficit was calculated. The components of loss were run-off 4% and deep percolation 10%.

The objective of this research was to correlate daily soil surface temperature changes and soil water evaporation losses to specific soil properties. Twenty test soils exhibiting a broad range of physical and chemical properties were placed in 50 x 50 x 28 cm boxes and monitored under dry and wet conditions from January to March, 1982. Soil moisture content, soil texture, soil albedo, and Munsell color were identified as the most important soil properties affecting daily changes in soil temperature and evaporation. The soils were placed into behavior groups based on these properties. Under dry conditions soil albedo, Munsell color value and sand content were the most important soil properties, whereas soil moisture was most important under wet soil conditions. Tables presenting tests for significance and simple linear regression relationship for each of the test soils plus the mean for all soils are included in the thesis. Equations in this thesis can be used to predict relationships between soil characteristics and the temperature-evaporation properties of Arizona soils.

The purpose of this investigation was to develop empirical relationships between pan evaporation and meteorological factors, under varied climatic conditions. Linear regression equations relating potential evapotranspiration and pan evaporation were derived for five stations in Arizona from January to December, 1983. Five climatological models (temperature, temperature-radiation, net radiation, solar radiation, and Penman combination) were applied to data collected from Mesa, Tucson (Campus Agricultural Center and UA 1), Oracle Agricultural Center, and Yuma. At each site high correlations were found between predicted values and open pan evaporation when data were grouped into monthly and weekly periods, although coefficients of variation were markedly different. Of the five methods, the net radiation equation, which required local calibration showed the poorest agreement between the empirical and measured values. Improvement in comparisons between empirical and measured values was observed with the temperature, radiation-temperature, and solar radiation methods. The Penman combination equation corresponded most closely to measured values.