Thesis (Ph. D.)--University of Hawaii at Manoa, 1995. / Includes bibliographical references (leaves 130-136). / Microfiche. / xi, 136 leaves, bound 29 cm

Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1974. / Bibliography: leaves 160-167. / xiv, 167 leaves ill

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 78-89).

Thesis (M.S.) University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (June 26, 2007) Includes bibliographical references.

CAPES / A adubação nitrogenada é freqüentemente observada como um eficiente fator nutricional fornecido a planta visando melhorar a produção de espécies forrageiras, necessitando ser entendido o comportamento do nitrogênio (N) no sistema. O experimento foi conduzido na área do Instituto Agronômico do Paraná (IAPAR) na estação experimental de Pato Branco, com objetivo de avaliar a dinâmica do N no sistema solo-planta em pastagem de Brachiaria plantaginea. O delineamento experimental foi o de blocos ao acaso com duas repetições. Os tratamentos foram arranjados em parcelas subdivididas. Nas parcelas foram alocados os períodos e nas sub-parcelas a combinação das três doses de N e duas intensidades de pastejo (Massa Alta e Massa Baixa), perfazendo seis tratamentos em esquema fatorial. As doses de N foram compostas de 0, 200 e 400 kg.ha-1 de N e as intensidades de pastejo preconizadas em massa baixa (MB), com 1.500 kg de MS.ha-1, e massa alta (MA) com 3.000 kg de MS.ha-1 em pastejo com lotação contínua e taxa de lotação variável. Utilizaram-se caprinos, meio sangue Bôer, com cinco meses de idade e peso médio de 21 Kg de peso vivo (PV), para definir as massas de forragem (MF) preconizadas. Avaliou-se a produção acumulada e total de biomassa aérea de papuã nos períodos experimentais, os índices nutricionais de nitrogênio, fósforo e potássio, também a curva de diluição, eficiência e recuperação do nitrogênio e o comportamento do nitrogênio no solo. A produção de forragem de B. plantaginea foi maior na dose intermediaria de N (200 kg de N.ha-1), atingindo uma produção de 19.834 kg de MS.ha-1, 31% a mais que no tratamento que não recebeu adubação nitrogenada. Os teores de N encontrados nas plantas que receberam adubação nitrogenada apresentaram valores superiores aos preconizados como críticos, resultando em conteúdos adequados deste elemento na planta, e, ao contrário, as plantas cultivadas sem adubação nitrogenadas apresentaram teores inferiores ao crítico, apontando desta forma que a curva de diluição de N é uma ferramenta adequada para diagnose de nutrição nitrogenada em pastagens. A máxima produtividade foi limitada pela falta de fósforo indicada pelo baixo índice de fósforo obtido conforme os teores do elemento na pastagem e a absorção de K aumentou com a adubação nitrogenada apresentando índices satisfatórios do elemento. A dose de 200 kg de N.ha-1 demonstrou-se a mais eficiente com taxas de recuperação de N superiores em 63% em relação a dose de 400 kg de N.ha-1. Não foi observada lixiviação das formas de nitrogênio inorgânicas estudas (nitrato e amônio) no perfil do solo e observou-se maior quantidade de nitrato e N-Mineral na menor massa de forragem após completada a quantidade de N proposta. / Nitrogen fertilization is usually noticed as an efficient nutritional factor offered to the plant with the aim to improve its production, being necessary to understand the nitrogen behave (N) in the system. The experiment was carried out at the Agronomist institute of Paraná (IAPAR), experimental unit of Pato Branco with the aim to evaluate the dynamic of N in the soil-plant system of a Brachiaria plantaginea. The experiment was laid out as random block design with two replications. The treatments were arranged in a split-plot model. At the plots were allocated the periods and at the sub-plots the combination of three levels of nitrogen and two grazing intensities (High mass and Low Mass), making six treatments in a factorial scheme. The levels of nitrogen used were composed of 0, 200 and 400 kg of N.ha-1 and the grazing intensities characterized by the low forage mass (LM) with 1.500 kg of DM.ha-1 and high forage mass (HM) with 3000 kg of DM.ha-1 in a continuous stocking rate. Were used goats half blood Boer with five months old and average life weight of 21 kg of live weight (LW) at the beginning of the experiment with the aim to adjust the forage mass (FM) wanted. Was evaluated the accumulate and total forage production of the papuã aerial biomass at the experimental periods, the nutritional indices of nitrogen, phosphorous and potassium and also the dilution curve, efficiency of N recovery and behave of nitrogen in the soil. The Brachiaria plantaginea forage production was higher at the nitrogen intermediate level (200 kg of N.ha-1), reaching an production of 19.834 kg of DM.ha-1, 31% more then treatment without nitrogen. The N levels found in the plants that received nitrogen fertilization showed higher values than the ones recognized as deficient, resulting in adequate contents of this element in the plant and, in the other hand, the plants cultivated without nitrogen showed levels below the one recognized as sufficient, showing with that the dilution curve of N is an adequate tool to diagnose the forage nitrogen nutrition. The highest production was limited by the lack of phosphorous showed by the phosphorous indices obtained according to the pasture element levels and the absorption of K increased with the nitrogen application, showing satisfactory level of the element. The 200 level of N.ha-1 showed to be the most efficient with recovery N levels 63% higher than the 400 kg.N.ha-1. There was no inorganic (NO3 - e NH4 +) N leaching found in the soil profile and was noticed higher quantities of NO3 - and mineral-N at the lower forage mass after finishing the total N applied.

CAPES / A adubação nitrogenada é freqüentemente observada como um eficiente fator nutricional fornecido a planta visando melhorar a produção de espécies forrageiras, necessitando ser entendido o comportamento do nitrogênio (N) no sistema. O experimento foi conduzido na área do Instituto Agronômico do Paraná (IAPAR) na estação experimental de Pato Branco, com objetivo de avaliar a dinâmica do N no sistema solo-planta em pastagem de Brachiaria plantaginea. O delineamento experimental foi o de blocos ao acaso com duas repetições. Os tratamentos foram arranjados em parcelas subdivididas. Nas parcelas foram alocados os períodos e nas sub-parcelas a combinação das três doses de N e duas intensidades de pastejo (Massa Alta e Massa Baixa), perfazendo seis tratamentos em esquema fatorial. As doses de N foram compostas de 0, 200 e 400 kg.ha-1 de N e as intensidades de pastejo preconizadas em massa baixa (MB), com 1.500 kg de MS.ha-1, e massa alta (MA) com 3.000 kg de MS.ha-1 em pastejo com lotação contínua e taxa de lotação variável. Utilizaram-se caprinos, meio sangue Bôer, com cinco meses de idade e peso médio de 21 Kg de peso vivo (PV), para definir as massas de forragem (MF) preconizadas. Avaliou-se a produção acumulada e total de biomassa aérea de papuã nos períodos experimentais, os índices nutricionais de nitrogênio, fósforo e potássio, também a curva de diluição, eficiência e recuperação do nitrogênio e o comportamento do nitrogênio no solo. A produção de forragem de B. plantaginea foi maior na dose intermediaria de N (200 kg de N.ha-1), atingindo uma produção de 19.834 kg de MS.ha-1, 31% a mais que no tratamento que não recebeu adubação nitrogenada. Os teores de N encontrados nas plantas que receberam adubação nitrogenada apresentaram valores superiores aos preconizados como críticos, resultando em conteúdos adequados deste elemento na planta, e, ao contrário, as plantas cultivadas sem adubação nitrogenadas apresentaram teores inferiores ao crítico, apontando desta forma que a curva de diluição de N é uma ferramenta adequada para diagnose de nutrição nitrogenada em pastagens. A máxima produtividade foi limitada pela falta de fósforo indicada pelo baixo índice de fósforo obtido conforme os teores do elemento na pastagem e a absorção de K aumentou com a adubação nitrogenada apresentando índices satisfatórios do elemento. A dose de 200 kg de N.ha-1 demonstrou-se a mais eficiente com taxas de recuperação de N superiores em 63% em relação a dose de 400 kg de N.ha-1. Não foi observada lixiviação das formas de nitrogênio inorgânicas estudas (nitrato e amônio) no perfil do solo e observou-se maior quantidade de nitrato e N-Mineral na menor massa de forragem após completada a quantidade de N proposta. / Nitrogen fertilization is usually noticed as an efficient nutritional factor offered to the plant with the aim to improve its production, being necessary to understand the nitrogen behave (N) in the system. The experiment was carried out at the Agronomist institute of Paraná (IAPAR), experimental unit of Pato Branco with the aim to evaluate the dynamic of N in the soil-plant system of a Brachiaria plantaginea. The experiment was laid out as random block design with two replications. The treatments were arranged in a split-plot model. At the plots were allocated the periods and at the sub-plots the combination of three levels of nitrogen and two grazing intensities (High mass and Low Mass), making six treatments in a factorial scheme. The levels of nitrogen used were composed of 0, 200 and 400 kg of N.ha-1 and the grazing intensities characterized by the low forage mass (LM) with 1.500 kg of DM.ha-1 and high forage mass (HM) with 3000 kg of DM.ha-1 in a continuous stocking rate. Were used goats half blood Boer with five months old and average life weight of 21 kg of live weight (LW) at the beginning of the experiment with the aim to adjust the forage mass (FM) wanted. Was evaluated the accumulate and total forage production of the papuã aerial biomass at the experimental periods, the nutritional indices of nitrogen, phosphorous and potassium and also the dilution curve, efficiency of N recovery and behave of nitrogen in the soil. The Brachiaria plantaginea forage production was higher at the nitrogen intermediate level (200 kg of N.ha-1), reaching an production of 19.834 kg of DM.ha-1, 31% more then treatment without nitrogen. The N levels found in the plants that received nitrogen fertilization showed higher values than the ones recognized as deficient, resulting in adequate contents of this element in the plant and, in the other hand, the plants cultivated without nitrogen showed levels below the one recognized as sufficient, showing with that the dilution curve of N is an adequate tool to diagnose the forage nitrogen nutrition. The highest production was limited by the lack of phosphorous showed by the phosphorous indices obtained according to the pasture element levels and the absorption of K increased with the nitrogen application, showing satisfactory level of the element. The 200 level of N.ha-1 showed to be the most efficient with recovery N levels 63% higher than the 400 kg.N.ha-1. There was no inorganic (NO3 - e NH4 +) N leaching found in the soil profile and was noticed higher quantities of NO3 - and mineral-N at the lower forage mass after finishing the total N applied.

An incubation technique was used to examine carbon mineralization and inorganic nitrogen accumulation in samples of Douglas-fir and alder forest floors developed over soils derived from granitic, ultrabasic and limestone parent materials in western British Columbia and Washington. Samples included L, F, and H or Hi horizons of Douglas-fir mor, raw moder, mull-like moder and mull forest floors and alder typical moder forest floors. Carbon dioxide production by the forest floor materials provided an estimate of gross carbon mineralization and an approximate indication of gross nitrogen mineralization. Comparison of inorganic nitrogen accumulated and gross carbon mineralized indicated that a large fraction of the mineralized inorganic nitrogen is immobilized by the microbial population and (or) lost to denitrification. The Hi horizons (organic horizons containing considerable incorporated mineral matter) accumulated more inorganic nitrogen than did the L and F horizons. Alder forest floors accumulated more inorganic nitrogen than did Douglas-fir forest floor materials. Alder L horizons tended to accumulate ammonium nitrogen while the F and Hi horizons accumulated nitrate nitrogen. Douglas-fir mor forest floors were distinguished from their mull and moder counterparts by slower decomposition and less inorganic nitrogen accumulation, and by largely accumulating ammonium nitrogen in all horizons. Irregular nitrogen accumulation curves, for some samples of Douglas-fir L and F horizons were probably due to denitrification losses. Incubation conditions favoring nitrification, with no plant sinks to remove accumulated inorganic nitrogen, may have favored denitrification losses. / Land and Food Systems, Faculty of / Graduate

Understanding the redistribution and fate of N is essential for justification of Best Management Practices (BMP). This project was conducted on a Hecla fine sandy loam (sandy, mixed, Aquic Haploboroll) soil at the BMP field site near Oakes, North Dakota. One objective of this investigation was to evaluate the residence times of N03- -N in 20 undisturbed lysimeters and its infiltration time through the soil profile to tile drains. Corn (Zea mays L.) was fertilized with 135 kg N ha -1 as ¹⁵N-enriched urea plus 13.5 and 48.1 kg N ha -1 preplant for 1993 and 1994, respectively. Urea-N was band applied to 20 and 10 undisturbed lysimeters at 2.0 and 5.93 atom percent (at %) ¹⁵N in 1993 and 1994, respectively. Average resident times of N03- -N in the lysimeters was 11.7 months. Lysimeter and tile drainage indicate the presence of preferential pathways. Residence times of N03- -N depend on frequency and intensity of precipitation events. Another objective was to determine what portion of the total N in the crop was from applied urea-N and what portion was from the native soil-N. Nitrogen plots received ¹⁵N enrichments of 4.25 and 5.93 at % ¹⁵N in 1993 and 1994, respectively. At the end of the 1993 and 1994 growing season, 41.5% and 35.7% of the labeled fertilizer N remained in the soil profile, while the total recovery of applied ¹⁵N in the soil-plant system was 86.2% and 75.4%, respectively. Low recoveries of applied N may have been the result of soil or aboveground plant biomass volatilization, or denitrification or preferential flow processes. Further research needs to be conducted with strict accountability of gaseous loss and the mechanism(s) responsible. / U.S. Bureau of Reclamation

No description available.

No description available.