Physical Sciences and Mathematics Commons^™

Effect Of Early Growth Cultivation On Beans And Sweet Corn, Raymond L. Cartee

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Investigations involving four cultivation treatments were conducted at the Utah State University Greenville Experimental Farm to determine the effect of these treatments on yields of beans and sweet corn. The effects of the different treatments on soil water content, soil temperature, and weed control in beans and corn were investigated. The effect of cultivation on the degree of root rot infection and the effect of different planting dates were also investigated in the bean study.

The pre-emergence treatment (ridged just before the plants emerge) produced a 48 percent greater bean yield and a 40 percent greater corn yield than the …

Model For Predicting Simultaneous Distribution Of Salt And Water In Soils, Satish C. Gupta

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Knowledge of water and salt movement in soils is necessary for development of a management scheme for controlling the quality of irrigation return flow. A computer model was developed to predict the distribution of water and salts in the root zone under varying initial and boundary conditions. The model consists of water flow and salt flow sub-models. The water flow sub-model considers the numerical approximation of the general water flow equation with modification for water loss by evapotranspiration (and thus root extraction). The salt flow sub-model considers the mass flow of salts, chemical exchange, precipitation or dissolution of CaCO_{3 …}

Potentiometric Titration Of Sulfate Using A Lead-Mercury Amalgam Indicator Electrode, Charles W. Robbins

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A lead sensitive indicator electrode was constructed with a 70 percent lead and 30 percent mercury amalgam billet. Sulfate concentrations in pure solutions, natural waters, and soil saturation extracts were determined potentiometrically using the lead-mercury amalgam indicator electrode and a standard calomel reference electrode. Sulfate concentrations over the range 0.4 to 20 milliequivalents sulfate per liter were determined with an automatic titrator and compared to a turbidimetric method for accuracy and precision. The values obtained by the two methods from twelve saturation extracts and three subsurface drainage waters were not significantly different and the potentiometric method was generally more precise. …

Model For Estimating Soil Water Flow, Water Content, Evapotranspiration And Root Extraction, Musa N. Nimah

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A mathematical model was developed to predict water content profiles, evapotranspiration, water flow from or to the water table, root extraction and root water potential at the surface as functions of time under unsteady state conditions.

The model was tested in the field at The Hullinger Farm near Vernal, Utah, in 1970 and 1971. Comparison of water content-depth profiles show excellent agreement at the end of a 9- day run in 1970 on oats seeded to alfalfa. In 1971 with alfalfa as the crop, the data show best agreement, between predicted and computed water content-depth profiles, 48 hours after any …

An Examination Of The Inorganic Nitrogen Status Of A Soil Of The Alaskan Coastal Tundra Plain, Norton R. Munn

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This experiment was designed to measure in situ concentrations of NH₄⁺ and NO₃^--N in a soil of the arctic coastal tundra plain, to determine if nitrification was taking place in this soil and to determine if the vascular plants growing in this soil could assimilate NH₄⁺-N.

The extractable NH₄⁺-N concentration was approximately 40 μg/g in the 0₁ horizon and 10 μg/g in the 0₂ horizon. The NO₃^--N concentration was approximately 5 μg/g in the 0¹ horizon and 4 μg/g in the 0_{2 …}

Evaluation Of The Filter Paper Method For Estimating Soil Water Potential, Samir Al-Khafaf

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The filter paper method for measuring soil water potential was evaluated. The method was calibrated using salt solutions (-1.4 bars to -22.4 bars), sample chamber psychrometer (-1 to -50 bars), pressure plate (-0.1 to -15 bars) and soil column at equilibrium (0 to -0.2 bars). It was found that the absolute temperature had little effect on the predicted soil water potential, but a temperature variation had a large effect. It was found that the temperature fluctuation must be small. The predicted water potential was influenced by the type of contact of the soil with the filter paper. It is suggested …