No description available.

No description available.

The solubility of calcium carbonate in calcareous soils was studied with a view of testing the validity of the application of equations based on calcite solubility in calcareous soils. For this purpose the solubility of calcium carbonate in calcareous soils was examined under a variety of experimental conditions. Calcareous soils equilibrated in water at constant partial pressure of carbon dioxide showed a state of supersaturation with respect to calcite. The values for pH-½pCa for each soil were constant, but varied from one soil to another. Varying the soil-water ratio over a range of 1:2 to 1:10 did not affect the constancy of pH-½pCa values in the soils studied. The addition of CaCl₂ varying in concentration from 0.0025 to 0.01 mole/l. did not affect the constancy of values for pH-½pCa. When dissolution of part of the calcareous materials present was effected by the addition of increments of a H-Resin or dilute HCl acid, the values for pH-½pCa did not remain constant. The reactions between orthophosphate solutions and calcareous soils varying in calcium content was examined. It was found that in all cases the initial rate of phosphorus fixation was rapid with about 98% of the phosphate added being fixed within 2 days. The calcium carbonate exerted its normal effect on the solution equilibrium regardless of the mechanism of the reaction between solid calcium carbonate and dilute solutions of KH₂PO₄. The application of solubility criteria revealed a state of supersaturation with respect to dicalcium phosphate. A study was made to determine whether the proton transfer mechanism associated with hydrated aluminum ions was responsible for the constancy of the values for pH-½pCa in soils. The constancy of ion ratios was studied in cation exchange resin suspensions. It was found that the values for pH-½pCa were constant in resins saturated with calcium and hydrogen over a range of calcium saturation from 21% to 85%. At 95% calcium saturation, constancy of pH-½pCa was not observed. In a calcium-aluminum resin saturated 47% with aluminum, the values for pH-½pCa were found to be relatively constant with a maximum difference of 0.08. / Land and Food Systems, Faculty of / Graduate

No description available.

No description available.

Call number: LD2668 .T4 1949 B74 / Master of Science

Typescript, etc.

Global climate change in either the form of global warming or global cooling is occurring relatively rapidly today. Studies have shown that increased levels of greenhouse gases, especially atmospheric carbon dioxide (CO₂) are the dominate component contributing to the change. A reduction in CO₂ may be influenced by making larger efforts to sequester carbon in soil and therefore to not only keep soil organic carbon (SOC) levels steady but by possibly increasing them through human assistance. Soil sequestration of carbon has been estimated to have one of the largest potentials to sequester carbon in the world. By some estimation up to 2 billion tons of carbon can be sequestered terrestrially. Therefore the efficient and repetitive monitoring of SOC on a local and global scale is a critical issue. The current soil measurement technique utilized around the world is chemical analysis of one form or another. Chemical analysis of soil is a well studied technique that returns relatively accurate results of density, moisture content, and elemental breakdown of a soil. However, chemical analysis is costly, time consuming, and destructive. As a result of the destructive nature of soil chemical analysis, repeated measurements of the same soil site is impossible. Also, due to time constraints, it would be difficult to analyze a large area utilizing chemical analysis. To surmount the inherent issues with chemical analysis a system based on inelastic neutron scattering (INS) is under development for non-destructive monitoring of carbon in soil. It is based on spectroscopy of gamma rays induced by fast (14 MeV) neutrons emanating isotropically from a D-T neutron generator (NG). The calibration of the INS system is a remains a challenge. Calibration of the system is necessary for relating the carbon gamma ray counts from the detectors to a carbon concentration in the soil volume measured. Utilizing a benchmarked Monte Carlo model of the INS system it is possible to create many calibration curves. The advantages of the model are that the calculations require a relatively short amount of time, and that all the soil variables are defined by the user.

Not available / text

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.