03157nas a2200205   4500008004100000245009900041210006900140260004300209490002100252520239400273653003702667653004302704653003202747653002002779653002602799653002502825100002002850700002802870856005302898       2016                        eng d00aThe effects of P fertilizer addition on P transformations on high-P fixing and grassland soils0 aeffects of P fertilizer addition on P transformations on highP f  aManhattan, KSbKansas State University0 vPhD Dissertation3 a<p>Although phosphorus (P) is an essential nutrient for the growth of plants, it is one of the most limiting nutrients in terms of availability as a high proportion of applied P rapidly transforms into insoluble forms with low solubility in soils. To further understand the fate of P applied to soils, two separate but related studies using three high P-fixing soil types each were used for which the objectives were to investigate the mobility, availability, and reaction products from two granular and one liquid P fertilizer alone or plus a fertilizer enhancement product. Energy dispersive spectroscopy showed a substantial amount of P remained in the granule following a 5-week incubation. At the end of the 35-day incubation period there was evidence that the fluid fertilizer was superior over the granular sources in terms of enhanced diffusion and extractability of P for three calcareous soils with varying levels of CaCO₃. Phosphorus x-ray absorption near-edge structure (XANES) spectroscopy results in conjunction with resin-extractable P indicated a strong negative correlation between Ca-P solids formed and P extractability, suggesting that degree of Ca-P formation limits P solubility. For the three acidic P-fixing soils the results were complex. In two out of three acid soils, liquid P treatments diffused farther from the application point than the granular treatments. Phosphorus XANES results suggested that Fe-P or Al-P interactions control the overall P solubility. Integration of pH, resin extractable-P and XANES results suggested the P retention mechanism was either dominated by adsorption or precipitation depending on soil pH. More acidic soil conditions favored precipitation.</p><p>The objectives of the third study were to observe how long-term (14 years) addition of P with or without N influences the inorganic and organic P pools in a native grassland soil using sequential fractionation, XANES, and &sup3;&sup1;P-nuclear magnetic resonance (NMR) spectroscopy. The overall results suggested that P and N fertilization and associated changes in plant productivity induced significant changes in soil P pools such as Ca-P, phytic acid, monoesters, and residual forms of P. The addition of P alone induced formation of inorganic P forms while the addition of P and N induced transformation of residual P forms into more labile and/or organic P forms.</p>10aHigh phosphorus-fixing acid soil10aHigh phosphorus-fixing calcareous soil10aHigh phosphorus-fixing soil10aSoil phosphorus10aSoil phosphorus cycle10aTall grassland soils1 aPierzynski, Joy1 aHettiarachchi, Ganga.M.  uhttp://krex.k-state.edu/dspace/handle/2097/34586