Phosphorus (P) inputs into water reservoirs are the primary cause for accelerated eutrophication affecting water quality. Attempts are underway to regulate inputs originating from concentrated animal feeding operations (CAFOs). The purpose of this research was to relate runoff dissolved (DP) and total P (TP) losses to site-specific characteristics from plots in CAFOs and compare them to their corresponding risk assessment using the Texas Phosphorus Index (PI). Initial studies showed that soil test P (STP) methods used in Texas by inductively coupled plasma were highly reproducible regardless of manure source or application rate. However, NH4OAc-EDTA extraction efficiency was increased with respect to other methods as soil conditions became less acidic, probably due to dissolution of the greater portion of Ca-bound P resulting in STP values that could be three times greater than those of Mehlich III for the same soil. Surface application of dairy manure to high pH soils were positively correlated to STP at various soil-sampling depths down to 15 cm. First order linear relationships between STP values and DP concentrations in runoff were statistically significant for extraction methods and sampling depths but were different among different soils under neutral to calcareous conditions. Attempts to reproduce this relationship on fields that received periodic applications of manure or effluent with various incubation periods failed, although there was a single highly significant relationship between STP and runoff DP for different soils when soil conditions were acid ( pH<6.5) with various sampling depths. Analyses of NH4OAc-EDTA extractable soil elements showed Mg was significantly correlated to DP concentration across various management and soils, indicating that Mg-bound P is a major component controlling P release into runoff. Use of the Texas PI reflected vegetation type closely, with grass-covered sites averaging the lowest risk rating, and having the lowest DP and TP losses, while conversely tilled sites had the highest. However, overall relationship was poor when estimates for erosion rates were used due to experimental design limitations. Use of measured erosion rates for plots and inclusion of extractable Mg improved correlations between PI rating to DP and TP losses, with r2 ranging from 0.60 to 0.87.

Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 173-184).

Thesis (M.A.)--University of Alabama at Birmingham, 2009. / Title from PDF title page (viewed Jan. 25, 2010). Includes bibliographical references (p. 63-68).

Thesis (Ph. D.)--Uppsala universitet, 2004. / Available also in print. Description based on contents viewed Aug. 12, 2004; title from title screen. Includes bibliographical references (p. 69-77).

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The majority of the light elements up to iron (Fe) are formed by successive rounds of thermonuclear fusion burning in the stellar interiors. The nuclei heavier than iron (Z>26) are being synthesized mainly by neutron-capture reactions - the astrophysical r-and s-processes. There are 35 neutron deficient stable isotopes between Se and Hg which are shielded from the rapid neutron capture by stable isobars. These so-called p-nuclei are produced in explosive stellar environments via photodisintegration reactions like (γ,n), (γ,p) and (γ,α) on r- or s-seed nuclei. The reaction rates of the p-nuclei are mostly based on theoretical parameterizations using statistical model calculations. At the bremsstrahlung facility of the superconducting electron accelerator ELBE, photon-induced reactions of the p-nuclei are being studied. In the scope of this thesis work, photodisintegration measurements of the p-nuclei 92Mo and 144Sm have been performed via the photoactivation technique. The residual nuclei resulting from photoactivation were studied via γ-ray spectroscopy. For the decay measurements of short-lived nuclei, a pneumatic delivery system has been used. In the case of 144Sm(°,p) and 144Sm(γ,α) reactions, the activated samarium samples with very low counting statistics were measured at the underground laboratory "Felsenkeller" in Dresden. The experimental activation yields for the 144Sm (γ,n), (γ,p) and (γ, α) and the 92Mo(γ,α) reactions were determined. It is to be emphasized that the (γ,p) and (γ,α) reactions were measured for the first time in a laboratory at astrophysically relevant energies. In all the mentioned experiments, special care was taken to determine the endpoint energy of the bremsstrahlung spectra by using the photodisintegration of deuteron. The 197Au(γ,n)196Au reaction has been established as an activation standard. The photoactivation yields for the 197Au(γ,n) and 144Sm(γ,n) reactions have been compared to the yield calculated using cross sections from previous photoneutron experiments. A comparison of the two data sets leads to a conclusion on the inaccuracies in previous data. The statistical uncertainties involved in the activation experiments are very small except for the case of decay spectra with weak counting statistics. The systematic uncertainties are mostly from the experimental determination of photon flux. A detailed discussion of the overall uncertainty is provided. Hauser-Feshbach statistical model calculations using TALYS and NON-SMOKER codes have been performed for all the concerned reactions. The experimental activation yields, in general, agree within a factor of 2 to the simulated yields using statistical model predictions. The sensitivity of the model codes to the nuclear physics inputs like optical-model potentials, nuclear level densities and γ-ray strength functions has been tested.

Three studies were conducted. In the first study, 12 Yorkshire barrows (initial BW of 23.2 ± 2.0 kg) were allotted to 2 dietary treatments with 6 replications per treatment using a completely randomized design to determine apparent Ca and P digestibility (AD), true digestibility (TD) and endogenous output (EO) in a corn/SBM-based diet. All pigs were placed in individual feeder pens that allowed for easy collection of individual feces. The AD of Ca and P were 28.4% and 23.9%, respectively. Their TD of 42% and 40% for Ca and P respectively were significantly (P < 0.05) higher than the corresponding AD. EO was 0.8g for Ca and 1.3g for P per kg of dry matter intake (DMI). In the second study, the optimal dietary ratio of true digestible Ca and P was determined in terms of its effect on growing pig performance, excretion of Ca and P in feces and urine in a corn/SBM-based diet using a randomized complete block design. Thirty six growing barrows (initial BW: 24.2 ± 1.9 kg) were allotted to 6 dietary treatments with 6 replications per block. Six corn/SBM-based diets with very similar nutrient contents were formulated but differed in their dietary ratio of Ca to P. The balances of Ca and P and their true digestibility/retention were calculated for each diet. Animal performance and true retention of both Ca and P was optimal (P < 0.05) with diet 2 with a true digestible Ca to P ratio of 0.82: 1 compared to other experimental diets. The third study was conducted with a similar protocol to that used in experiment 1 involving 12 barrows (initial BW: 23.9 ± 1.1 kg) to determine Mg, Cu, Fe, Mn, Se and Zn TD values for the growing pig. Se and Zn AD of 73.9% and 9.5% significantly (P < 0.05) underestimated their TD of 82.1% and 15%, respectively. Se and Zn EO were 0.00004mg and 0.01 mg/kg of DMI, respectively. The TD and EO for Mg, Cu, Fe and Mn could not be estimated because of their negative AD.