The yield, fruiting habits, plant nitrogen uptake, dry matter production, and boll and fiber properties were studied in relation to nitrogen fertilizer and water application rate interactions in trickle-irrigated cotton. Nitrogen applications did not significantly increase yields because of high initial soil nitrogen and nitrogen added with the irrigation water. Significant yield differences did exist between the 60% consumption use (CU) irrigation level and the 90% and 120% CU irrigation levels. The 60% CU level resulted in appreciable plant water stress and appreciably lower yields. Nitrogen additions significantly increased seasonal plant petiole NO₃-N values as well as the number of flowers produced during the growing season. Increased water application rate lengthened the periods of peak flowering and peak boll production but had no effect on petiole NO₃-N. Increased water application rate did not significantly increase boll production, but an increasing trend of increased boll production with increasing water application rates was evident. Nitrogen applications did not significantly increase boll production, but percent boll set for the control treatment was higher. Both nitrogen additions and increased water application rates increased plant nitrogen uptake, which ranged from 163 kg N/ha to 242 kg N/ha for the water levels and 188 kg N/ha to 220 kg N/ha for the nitrogen treatments. Increased water application rates significantly increased dry matter production during the growing season. Nitrogen and water application rates affected only a few boll and fiber properties. Average boll size was increased significantly with increasing water application rates. This partially accounted for the higher yield observed at the higher irrigation levels.

The University of Arizona produces different types of radioactively contaminated waste. It is shipped to a burial site located on the Oracle Agricultural Center in Pinal County, Arizona and disposed of in shallow pits. This study dealt with water movement at the disposal site. Monitoring of water movement through young pits was accomplished with a neutron probe. It was found that due to slumping and cracking of the pit cap, the younger pits were very susceptible to greater than normal water infiltration. Further data were gathered around the older pits by deep soil sampling for tritium activity. Water fluxes and travel times to the major aquifer were calculated from these data. Estimates of travel times range from 40 to 230,000 years to reach the principal aquifer at 150 m.

Field and greenhouse experiments to determine the response of grapes to saline irrigation water were conducted. The goal of this research were: (1) to study the effect of salinity on grape and wine quantity and quality and (2) to evaluate the degree of salt tolerance of some of the grape rootstocks. For the greenhouse study, seven grape rootstocks were grown in the soil columns irrigated with three levels of salinity, EC of 0.45, 2.5, and 5 mmhos/cm. The later two waters were prepared by adding MgSO₄ and CaC1₂ salts to tap water with EC of 0.45 mmhos/cm. Shoot growth, pruning weight, leaf area, and trunk diameter were significantly reduced by salinity. Reduction in shoot growth and pruning weight were more pronounced than leaf area and trunk diameter. Maximum ECₑ values (1007 reduction in growth) varied from 8.81 mmhos/cm for 41B rootstock to 16.43 mmhos/cm for Ramsey rootstock. Maximum ECₑ for Barbera (Vitis vinifera) was 11.04 mmhos/cm. Based on percent reduction in growth, the relative tolerance of grapes could be arranged as follows: Ramsey > 5BB > SO4 > 1613 > Barbera > 99R > 41B. The field study included two sources of water and six grape rootstocks which were grafted to Barbera. Two sources of irrigation water were city and well water with EC of 0.42 and 2.6 mmhos/cm, respectively. The response of grapes to salinity was evaluated by fruit yield and pruning weight. Well water application significantly reduced fruit yield and pruning weight. The average fruit yield and pruning weight of Barbera grapes with all the rootstocks decreased by 49.5 7e and 26.7 7e with the well water compared to the city water, respectively. Must and wine analysis indicated that salt treated grape had higher total acidity and lower pH. Alcohol of the wines was not affected uniformly by treatment. Except for 99R rootstocks, the color of the wines were darker in city water than well water. Quality of wine from 3309 rootstock was lowered considerably by well water. With well water, only Barbera wine from 5BB rootstock appeared to be commercially acceptable. The six rootstocks differed from each other in their ability to growth in saline condition. Barbera grape grafted on 5BB and Ramsey rootstocks showed higher tolerance to salinity than Barbera on 99R, 3309, Harmony, and 41B rootstocks.

A field experiment to determine the effect of acidifying amendments and chiseling on water intake rate was conducted on the University of Arizona Experimental Farm at Marana. There was a total of 24 plots with six replications of each of the following treatments: sulfuric acid, Nitrosul, chiseling, and the control. The soil type was Pima clay loam. Four basin irrigations were applied during the summer of 1973 and the rate of infiltration was recorded for each plot. Chiseling to a depth of 50 cm was done prior to the first irrigation. The acidifying amendments were applied in the water during the first irrigation. Sulfuric acid and Nitrosul treated plots gave in general higher infiltration rates as compared with the control plots, but it was statistically significant only in the second irrigation. No significant response was obtained with chiseling. Soil analyses indicated a slight decrease in pH and SAR, and an increase in water holding capacity with the use of the acidifying amendments. Yields of sudangrass were not significantly different among treatments,

The effect of sulfuric acid applied to irrigation water on sodium adsorption ratio, exchangeable sodium percentage, and saturated hydraulic conductivity was studied by one greenhouse and two laboratory experiments using five soil samples and five different waters mixed to simulate those used for irrigation in the Southwestern United States. Application of sulfuric acid to the irrigation water decreased the sodium adsorption ratio and the exchangeable sodium percentage. Conventional equations based on the pile parameter over-estimate the effect of bicarbonates on the sodium adsorption ratio, while the equation based on carbonate equilibrium gave a more realistic estimate. The measured exchangeable sodium percentage was found to be proportional to the calculated sodium adsorption ratio. The proportionality constant for the five soils studied was 0.76 divided by the square root of the leaching fraction. Acid application also increased the rate of water movement when sodium adsorption ratio was greater than 7.0 in some soils without lowering the pH to acidic ranges.

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.

The movement of salts in soils following application of feedlot wastes was studied experimentally and theoretically. The objectives of the study were (1) to evaluate the movement of salts in the soil following heavy application of animal wastes as related to the aggregate sizes of manure and water management practices and (2) to develop a mathematical model to predict the movement of salts within the soil and manure mixture. In the experimental study, air dried manure was formed into three distinct sizes, small (to pass 40 mesh sieve), medium (0.9 am in diameter, 1.2 cm in length), and large (1.8 cm in diameter, 1.8 cm in length). Soil columns of 15 cm inside diameter were packed with 30 cm of a soil-manure mixture over a 10 cm depth of soil. The manure application rate was equivalent to 100 metric tons/ha calculated on the basis of the cross-sectional area of the column. A total of five pore volumes of water was passed through the soil under continuous and intermittent water applications. The leachates were collected in 1/2 pore volume increments and the volume, EC, and pH determined immediately. Within 48 hours of the sampling, the leachates were analyzed for Na, K, Ca, Mg, Cl, and five trace elements (Fe, Mn, Zn, Cu, and Ni). The EC of the leachate for the first 1/2 pore volume was significantly (1% level) highest for the small-sized aggregates and the lowest for the large aggregate treatments under both moisture regimes. During the second increment, the order was reversed. In the later water applications, the EC for small aggregates was higher than the other sizes. There were no significant differences between the EC of the leachate from medium and large aggregate treatments during the later periods under either water treatments. Under both moisture regimes, the amount of Na removed from small aggregates decreased more rapidly than the other sizes. More than 90% of the total Na added to the system by manure was removed from the small aggregate treatment. In contrast, the highest amount of K removed (895 mg from small-sized aggregates under continuous leaching' represents about 35% of the total amount present In the manure applied. More Ca was removed from the small-sized aggregate treatments under both moisture regimes than was added by manure application. As for Mg the pattern of the removal was similar to that of Ca. No Cl was detected in the leachate after the fifth 1/2 pore volume was displaced. A mathematical model was developed to predict the movement of readily soluble ions such as Na, K, and Cl from different aggregate sizes of manure. The theoretical curves were compared with earlier experimental data and the parameters appearing in the mathematical equation were estimated. The results for Cl, Na, and K are presented graphically, and the estimated parameters as well as the values of the square roots of the sum of the squares between the theoretical and experimental values as percentage of the sum of the experimental values (SSR) are reported. From the low value of SSR's, it is evident that the model can predict the movement of the readily soluble ions from different aggregate sizes of manure quite accurately. A discussion on the suitability of the model for different sizes of manure aggregates and also a comparison between two different procedures to fit the model to the experimental data are given. In addition, a three phase theoretical model was developed to describe the movement of readily soluble ions from a soil-manure-water system. Experimental data were used in testing the model. The results for Na, K, and Cl are presented graphically. Estimated parameters for the experimental system and the values of SSR are presented. This model also can predict the movement of readily soluble ions from a soil-manure-water system.