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| Registros recuperados: 38 | |
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| Oliveira Filho,Jair da C.; Oliveira,Rubens A. de; Oliveira,Ednaldo M. de; Cecon,Paulo R.; Martins,Carlos E.. |
| The objective of this study was to evaluate the effects of the application of different water depths and nitrogen and potassium doses in the quality of Tanzania grass, in the southern of the state of Tocantins. The experiment was conducted on strips of traditional sprinklers, and used, as treatments, a mixture of fertilizer combinations of N and K2O always in the ratio of 1 N:0.8 K2O. This study determined throughout the experiment: plant height (PH), the crude protein (CP) and neutral detergent fiber (NDF). The highest plant height obtained was 132.4 cm, with a fertilizer dose of 691.71 kg ha-1 in the proportion of N:0.8 K2O, in other words, 384.28 kg ha-1 of N and 307.43 kg ha-1 of K2O, and water depth of 80% of the ETc. The highest crude protein content... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Nitrogen fertilizer; Irrigated pasture; Panicum maximum. |
| Ano: 2012 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-69162012000400007 |
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| Flores,Rilner A.; Urquiaga,Segundo; Alves,Bruno J. R.; Collier,Leonardo S.; Boddey,Robert M.. |
| The objective of this study was to evaluate the performance of two genotypes of elephant grass, fertilized with and without N, for biomass production for energy use under the edaphoclimatic conditions of the Cerrado. The genotypes Roxo and Paraíso, grown in a field experiment in a Latosol in the Cerrado region were evaluated for biomass yield, nitrogen accumulation, C:N and stem:leaf ratios, fibre, ash and P and K contents and calorific value. The accumulated dry biomass ranged from 30 to 42 Mg ha-1 and showed no response to nitrogen fertilization with the lowest biomass obtained by the genotype Paraíso and the highest by Roxo. The total N accumulation followed the same pattern as for dry matter, ranging from 347 to 539 kg N ha-1. C:N and stem:leaf ratio... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Pennisetum purpureum; Bioenergy; Nitrogen fertilizer. |
| Ano: 2012 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-69162012000500003 |
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| Luz,José MQ; Queiroz,Angélica A; Oliveira,Roberta C. |
| A alta resposta da batateira à adição de nutrientes ao solo requer atenção especial aos aspectos relacionados à fertilidade, especialmente o nitrogênio (N), por ser o nutriente que ocasiona maior impacto na produtividade. Com o objetivo de identificar o teor crítico de N na cultura da batata em função das suas doses, realizou-se um experimento em Perdizes-MG, entre os meses de julho e novembro de 2010 com a cultivar Asterix. O delineamento experimental foi de blocos ao acaso, com cinco doses de N (0, 70, 140, 210 e 280 kg ha-1) e quatro repetições. As mesmas foram parceladas, sendo 20% da dose aplicada no momento do plantio e 80% em cobertura, juntamente com a operação da amontoa, 30 dias após o plantio. O restante da adubação foi composta por 400 kg ha-1... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Solanum tuberosum; Adubação nitrogenada; Produtividade; Teor de nitrogênio foliar; Solanum tuberosum; Nitrogen fertilizer; Productivity; Nitrogen leaf level. |
| Ano: 2014 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-05362014000200225 |
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| ELHAKEM,A.H.; ABD EL-SALAM,M.M.. |
| ABSTRACT: This study evaluates the effect of urea on growth of herbicide-treated maize and its accumulation in the soil. When the seedlings were 15 days old, the plots were divided into five groups. One group served as control, two received treatments with metolachlor and isoproturon at the dose of 1.5 kg ha-1 and 2.5 L ha-1, respectively. The two remaining groups received the same dose of herbicide along with urea added at a rate of 129 kg ha-1. The application of the two herbicides appeared to cause a significant decrease in shoot dry weight, photosynthetic pigments, d-aminolevulinate dehydratase enzyme [ALA-D, EC 4.2.1.24] and total soluble carbohydrates of the maize plants. The application of urea appeared to alleviate the effects of both herbicides on... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Maize; Soil accumulation; Nitrogen fertilizer. |
| Ano: 2018 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582018000100308 |
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| Roberts, Roland K.; Walters, Jeremy T.; Larson, James A.; English, Burton C.; Howard, Donald D.. |
| Interactions among the nitrogen (N) fertilization rate, N source, and disease severity can affect mean yield and yield in conservation tillage wheat production. A Just-Pope model was used to evaluate the effects of N rate, N source, and disease on the spring N fertilization decision. Ammonium nitrate (AN) was the utility-maximizing N source, regardless of risk preferences. The net-return-maximizing AN rate was 92 lb N/acre, providing $0.52/acre higher net returns than the best alternative N source (urea). If a farmer could anticipate a higher-than-average Take-All Root Rot infection, the difference in optimal net returns between AN and urea would increase to $35.11/acre. |
| Tipo: Journal Article |
Palavras-chave: Certainty equivalent; Blume-Blotch; Nitrogen fertilizer; Nitrogen source; Risk; Take-All; Winter wheat; D21; D81; Q12. |
| Ano: 2004 |
URL: http://purl.umn.edu/43444 |
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| Paulson, Nicholas D.; Babcock, Bruce A.. |
| The production literature has shown that inputs such as fertilizer can be defined as risk-increasing. However, farmers also consistently overapply nitrogen. A model of optimal input use under uncertainty is used to address this paradox. Using experimental data, a stochastic production relationship between yield and soil nitrate is estimated. Numerical results show that input uncertainty may cause farmers to overapply nitrogen. Survey data suggest that farmers are risk averse, but prefer small chances of high yields compared to small chances of crop failures when expected yields are equivalent. Furthermore, yield risk and yield variability are not equivalent. |
| Tipo: Journal Article |
Palavras-chave: Corn; Nitrogen fertilizer; Risk-increasing; Yield risk; Crop Production/Industries. |
| Ano: 2010 |
URL: http://purl.umn.edu/97853 |
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| Kering, Maru K.; Biermacher, Jon T.; Reuter, Ryan; Butler, Twain; Springer, Job D.; Rogers, James K.; Blanton, John, Jr.; Bouton, Joe H.; Guretzky, John A.. |
| Stocker cattle grazing warm season perennial grasses is an important economic activity in the southern Great Plains. Substantial increases in the price of nitrogen fertilizer is negatively affecting forage producers’ profitability. Two alternative nitrogen management systems that use annual and perennial legumes have been developed for bermudagrass pastures. The goal of the study is to determine if the legumes systems are more profitable than the conventional practice of applying synthetic sources of nitrogen. Results of the two-year grazing study show that the legume systems could not compete economically with the common practice. |
| Tipo: Conference Paper or Presentation |
Palavras-chave: Economics; Grazing; Legumes; Bermudagrass; Nitrogen fertilizer; Stocker cattle; Crop Production/Industries; Farm Management; Production Economics. |
| Ano: 2010 |
URL: http://purl.umn.edu/56525 |
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| Kim, C.S.; Hallahan, Charles B.; Taylor, Harold; Schluter, Gerald E.. |
| This article examines the effects of increasing market concentration level in the U.S. nitrogen fertilizer industry. Results indicate that the costs of market power are greater than the benefits of market concentration, in terms of manufacturing cost efficiency. To provide a stable nitrogen fertilizer supply at a relatively low price, it may be necessary to control natural gas price and/or reduce new import barriers from Middle East and former member states of the Soviet Union, where low cost gas is produced as a byproduct. Keywords: Nitrogen fertilizer, oligopoly, economies of size, market power, cost-efficiency. |
| Tipo: Conference Paper or Presentation |
Palavras-chave: Nitrogen fertilizer; Oligopoly; Economies of size; Market power; Cost-efficiency.; Marketing. |
| Ano: 2002 |
URL: http://purl.umn.edu/19674 |
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| Graybeal, Dale K.. |
| A logistic growth equation with time and location varying parameters was used to model corn response to applied nitrogen. A nonlinear dummy-variable regression model provided a parsimonious representation of site and time effects on parameter values. The model was used to test for the equality of the mean marginal product of nitrogen fertilizer between locations on the coastal plain of North Carolina. Monte Carlo simulation and bootstrap simulation were used to construct finite sample covariance estimates. Results support rejection of the hypothesis that mean marginal products are equal when nitrogen is applied at 168 kg/ac. A comparison of bootstrapped errors and asymptotic errors suggests that results based on asymptotic theory are fairly reliable in... |
| Tipo: Journal Article |
Palavras-chave: Bootstrap; Corn yield; Marginal product; Nitrogen fertilizer; Nonlinear regression; Crop Production/Industries; C200; C150; Q100. |
| Ano: 2000 |
URL: http://purl.umn.edu/15502 |
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| Huang, Wen-Yuan. |
| Nitrogen applied before planting is more vulnerable to loss to the environment than nitrogen applied during the growing season, but the growing season application can increase the risk of lower yields caused by adverse weather that prohibits farmers to complete N application. An expected utility framework is used to illustrate the potential economic benefit of insurance for a farmer to reduce this risk of cost. An expected-value variance analysis is used to illustrate the potential benefit of insurance to Iowa corn growers who apply N fertilizer only during the growing season. |
| Tipo: Journal Article |
Palavras-chave: Insurance; Nitrogen fertilizer; Application timings; Risk and Uncertainty. |
| Ano: 2002 |
URL: http://purl.umn.edu/15520 |
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| Fontoura,Sandra Mara Vieira; Bayer,Cimélio. |
| Ammonia (NH3) volatilization can reduce the efficiency of urea applied to the surface of no-till (NT) soils. Thus, the objectives of this study were to evaluate the magnitude of NH3 losses from surface-applied urea and to determine if this loss justifies the urea incorporation in soil or its substitution for other N sources under the subtropical climatic conditions of South-Central region of Paraná State, Brazil. The experiment, performed over four harvesting seasons in a clayey Hapludox followed a randomized block design with four replicates. A single dose of N (150 kg ha-1) to V5 growth stage of corn cultivated under NT system was applied and seven treatments were evaluated, including surface-applied urea, ammonium sulfate, ammonium nitrate, urea with... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Nitrogen fertilizer; Urea; Corn; Urease. |
| Ano: 2010 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832010000500020 |
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| Registros recuperados: 38 | |
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