The data of 14 soils were used to compute the ion activity product (IAP), the ratio of the ion activity product and to the solubility product (Ksp) of the pure minerals (IAP/Ksp) and to estimate the solid activity coefficients (SAC) of the soil components. The value of IAP and SAC of AlPO4 differs from soil to soil and increases with increasing P added to soil in acid soils and for calcium phosphate in basic soils. Magnesium apparently did not cause P adsorption or precipitation in the soils studied. The SAC of aluminum phosphate ranged from 10 to 10000 in acid soils. The mole fraction of the total phosphate in soil seemed to be a more satisfactory basis for calculating the concentration of the solid phase than was measurements of the available phosphate.

Orientador: Daniel Marcos Bonotto / Banca: Marta Silvia Maria Mantovani / Banca: Sonia Maria Barros de Oliveira / Banca: Gilberto José Garcia / Banca: Jairo Roberto Jiménez-Rueda / Resumo: Este trabalho visou estudar o comportamento geoquímico de radionuclídeos e metais pesados em solos de uso agrícola na bacia do Rio Corumbataí (SP). A concentração e variabilidade natural em rochas sedimentares na bacia do Rio Corumbataí segue a tendência Ca > Mg > K > Na, com baixa concentração natural de metais pesados e radionuclídeos. A distribuição das taxas de dose nos solos mostra que ocorre uma maior taxa de exposição na região sul da bacia do Rio Corumbataí, onde há aplicação de fertilizantes fosfatados, corretivos agrícolas e vinhaça em plantações de cana-de-açúcar. Metais pesados e radionuclídeos existentes nos fertilizantes fosfatados e corretivos agrícolas são adicionados anualmente nas plantações de cana-de-açúcar, mas se usados de acordo com as taxas recomendadas, não aumentam suas concentrações em solos para níveis perigosos. Assim, há baixa transferência destes elementos dos solos para a cana-de-açúcar na bacia do Rio Corumbataí, não oferecem nenhum risco ao ecossistema e à saúde do animal e do homem. Palavras-chave: Radionuclídeos e metais pesados, Solos e fertilizantes, Plantações de canade- açúcar, Cadeia alimentar. / Abstract: The purpose of this research was to study the geochemical behavior of radionuclides and heavy metals in soils of agricultural use at Corumbataí River basin (SP). The natural concentration and variability in sedimentary rocks at Corumbataí river basin follow the trend Ca > Mg > K > Na, with the concentration of heavy metals and radionuclides. The distribution of exposure rate in soils shows the occurrence of higher values towards south of the Corumbataí river basin, region where are applied phosphate fertilizers, amendments and vinhaça in sugar cane crops. Heavy metals and radionuclides incorporated in phosphate fertilizers and amendments are annually added during the fertilization process in the sugar cane crops, but if they are utilized in accordance with the recommended rate, they do not rise the concentration levels in soils up to hazards levels. Thus, they are lower transferred from soils to sugar cane at Corumbataí river basin, not offering hazard to the ecosystem and animal or human health. / Doutor

Typescript (photocopy). / Digitized by Kansas Correctional Industries

This thesis examines the response to P fertiliser by wheat crops growing in the vertosol soils of the low rainfall areas of the northern grain zone of eastern Australia. Farmers in this region depend on water accumulated from rainfall over a fallow period and stored in the subsoil to increase wheat grain yield beyond that normally achievable from in-crop rainfall and to decrease the production risks due to rainfall variability. The large variability in stored water, seasonal rainfall and subsoil properties result in extremely varied yield and yield responses to P fertiliser between seasons and between sites. Finally, as a practical guide to predicting wheat response to P fertilizer: 1/. current sampling strategies of determining P only in the surface 10 cm appear to be adequate for soils with bicarbonate P concentrations greater than 15 mg/kg. 2/. For soils with lower concentrations in the surface, sampling of 80 cm is recommended. Crops with a mean concentration of bicarbonate P greater than 7 mg/kg between 10 - 80 cm are unlikely to respond to P fertiliser. 3/. No increase in profitable grain yield response was found for fertiliser applications greater than 10 kg P/ha. / Doctor of Philosophy (PhD)

Organic phosphorus (P$ sb{ rm o}$) in farm animal wastes must be mineralized to inorganic P for subsequent plant use. This study was conducted to determine if feed additives affect P$ sb{ rm o}$ mineralization, manure decomposition, and plant growth. Feed additives in aqueous systems affected the P mineralization of inositol hexaphosphate by phytase and of adenosine monophosphate by alkaline phosphatase. Pronounced effects were produced by bacitracin and both enzymes and by neomycin on phytase. Feed additives in dairy cattle (Bos taurus L.) manure produced effects on microbial activity as measured by gas production that differed from those produced on fecal phosphatase activity. Additives applied directly or with manure to Ste. Rosalie clay, Greensboro loam, or silica sand had no effect on barley (Hordeum vulgare L.) yield but did produce additive, rate, growth medium, and manure dependent effects on plant P concentration and soil phosphatase activity. Therefore, each feed additive must be independently evaluated to determine its effect on biological systems.

Incubation mixtures of liquid hog manure (LHM), with and without monocalcium phosphate (MCP) were added to an Ormstown silty clay loam and a Ste. Rosalie clay. Ryegrass (Lolium multiflorum Lam.) was cultivated in a pot study in order to determine yield, total P uptake and soil P content as affected by various P and manure treatments. / Aeration of LHM with MCP was successful in reducing ammonia volatilization by 62.4%. However, for both soils, neither of the treatments; LHM amended and aerated with MCP and applied at 32 t ha$ sp{-1}$ LHM containing 513 kg $ rm P sb2O sb5 ha sp{-1}$ from MCP nor LHM aerated without MCP applied at 32 t ha$ sp{-1}$ LHM, plus 513 kg $ rm P sb2O sb5 ha sp{-1}$ from MCP, significantly affected ryegrass yields compared to the lone addition of MCP fertilizer (513 kg $ rm P sb2O sb5 ha sp{-1}).$ Total P uptake in ryegrass was significantly higher for the incubated treatments in the Ste. Rosalie soil alone. / Although additions of LHM or MCP and LHM-MCP combinations affected Mehlich-III and Hedley P fractions, the incubation of MCP with LHM did not significantly increase either inorganic- or organic-P fractions when compared to MCP alone. Therefore, premixing MCP with the LHM had no effect on improving P availability in either the Ormstown or Ste. Rosalie soils.

Crop-available zinc is affected by P-Zn interactions in soils. Orthophosphate (OP) additions may decrease or have no effect, while pyrophosphate (PP) may increase or have no effect on Zn solubility. Mechanisms involved in the interactions are not well understood and need to be quantified on agricultural soils subjected to P fertilization. / Top and sub-samples from three Quebec agricultural soils were equilibrated with OP or PP solutions, then with Zn solutions, and finally with solutions containing neither P nor Zn. The first equilibration evaluated P sorption effects on soil cation exchange capacity (CEC), the second equilibration evaluated Zn sorption (Zn$ sb{ rm s}$) after P sorption, and the third Zn desorption (Zn$ sb{ rm D}$) as related to added P. Subsequently, Zn fractions were extracted sequentially with KNO$ sb3$ (Zn$ sb{ rm KNO3}$), NaOH (Zn$ sb{ rm NaOH}$) solutions and concentrated HNO$ sb3$ + H$ sb2$O$ sb2$ (Zn$ sb{ rm HNO3}$). Autoclaved soils were used for OP and PP comparisons, and non-autoclaved soils were used for OP determinations. / Autoclaving reduced dithionite-citrate extractable Fe and Al materials. In both autoclaved and non-autoclaved soils, one mmole sorbed P as PP or OP resulted in increases in CEC from 0.52-1.24 mmole (+). Comparison between OP and PP in the autoclaved soils indicated that the increased CEC per mmole sorbed was greater with sorbed OP than with PP, while at the same rate of P addition, the absolute increased CEC was more with sorbed PP than with OP due to greater P sorption as PP compared to OP. Both sorbed OP or PP in autoclaved soils and sorbed OP in non-autoclaved soils increased specific Zn sorption in association with oxide materials. The effect was more significant with PP than with OP, as indicated by the observations: (1) P sorption increased Zn sorption but reduced Zn desorption, (2) P sorption reduced KNO$ sb3$- but increased NaOH- and HNO$ sb3$-extractable Zn, and (3) P sorption increased the difference between Zn sorbed and Zn extracted with KNO$ sb3$. These effects were more significant in coarser than finer textured soils. Results suggested that Zn fertilizers should be separated from P fertilizers to avoid enhanced Zn sorption and reduced Zn desorption.

Hydrolysis and adsorption-desorption reaction of pyrophosphate (PP) and orthophosphate (OP) were studied in two Quebec soils (St. Bernard and Dalhousie) and three minerals (goethite, kaolinite, and montmorillonite). Soil and soil mineral samples were fractionated by size into two separates. / Soil and goethite samples adsorbed more OP than PP whereas kaolinite and montmorillonite adsorbed similar amounts of OP and PP. Pyrophosphate and orthophosphate adsorption was found to be related significantly to extractable Fe. Furthermore, kaolinite and montmorillonite desorbed similar amounts of OP and PP whereas more OP than PP was desorbed from soil and goethite samples. Moreover, adsorption of OP and PP was found to be mainly chemical adsorption. Smaller particle size induced higher P adsorption and desorption from both P sources compared with the coarse particle size. / Goethite samples had slower rates of hydrolysis compared to soil and clay mineral samples. Furthermore, kalolinite and montmorillonite did not increase the rate of PP hydrolysis even with reduced adsorption of PP compared to soil and goethite samples. Chemical hydrolysis was found to be a significant portion of the total hydrolysis. Smaller particle size and high PP adsorption induced smaller PP hydrolysis than with coarse particles. Moreover, added OP reduced the amount of PP remaining nonhydrolyzed. First-order rates of PP hydrolysis were faster in nonautoclaved than autoclaved samples. Rate of PP hydrolysis increased with increased temperature and the effect of temperature was more obvious in the autoclaved than nonautoclaved samples.

Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1974. / Bibliography: leaves 191-204. / xvii, 204 leaves ill

Thesis (M.S.)--Auburn University, 2007. / Abstract. Includes bibliographic references (ℓ. 54-62)