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| Alfaro,Marta; Salazar,Francisco. |
| Producto de los tratados de libre comercio firmados por Chile, que auguran la apertura de mercados para la exportación de productos lácteos y cárnicos, se espera que la actividad ganadera del Sur del país se incremente e intensifique. A pesar del conocimiento técnico disponible para el incremento de la productividad del rubro, poco se sabe con certeza sobre el impacto ambiental de esta actividad, en especial sobre cursos de agua, a pesar de que los ríos y lagos de la región son además la base de otras actividades económicas de importancia, como la acuicultura y el turismo. En países desarrollados se ha demostrado que existe una fuerte relación causa-efecto entre la actividad ganadera y la polución difusa de cursos de agua superficiales, en especial de su... |
| Tipo: Journal article |
Palavras-chave: Nitrógeno; Fósforo; Producción de leche; Producción de carne; Impacto ambiental. |
| Ano: 2005 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0365-28072005000300012 |
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| Alfaro,Marta; Bernier,René; Iraira,Sergio. |
| Two experiments were carried out to evaluate the effect of source and rate of sulphur (S) on yield and quality of a wheat (Triticum aestivum L.) crop and a permanent naturalized pasture in southern Chile. In the wheat trial, calcium sulphate (SCA) and magnesium sulphate (SMG) were tested (45 and 90 kg S ha-1). In the pasture trial, an additional potassium-magnesium sulphate (SKMG) treatment was considered. In both trials fertilizers were sprayed and a control treatment was included. In the wheat trial all aspects affecting yield components were evaluated: yield, nitrogen (N), phosphorus (P) and S concentration in plants and seed, and albumen quality were evaluated. In the pasture trial, the yield and nutritional quality (foliar concentration of N, P, S... |
| Tipo: Journal article |
Palavras-chave: Protein; Digestibility; Gluten; Nutrient budgets balances; Proteína; Digestibilidad; Gluten; Balances de nutrientes. |
| Ano: 2006 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0365-28072006000300007 |
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| Núñez,Pedro A.; Demanet,Rolando; Misselbrook,Tom H.; Alfaro,Marta; Mora,María de la Luz. |
| Chilean livestock production systems have intensified over the last years, with increasing amounts of N fertilizer inputs creating the potentiality for environmental damage through N pollution of water and air, so that alternative production strategies have been developed to reduce such environmental impacts. This study assesses N losses under different grazing frequencies and intensities on permanent pasture (Lolium perenne L., Festuca arundinacea Schreb., Dactylis glomerata L., and Trifolium repens L.) on an Andisol in Southern Chile. Four grazing strategies were evaluated: frequent-heavy (FH), frequent-light (FL), infrequent-heavy (IH), infrequent-light (IL), and a no grazing control (C) treatment, and each with three replicates in a randomized complete... |
| Tipo: Journal article |
Palavras-chave: Ammonium; Grazing; Leaching; Nitrate; NH3 volatilization. |
| Ano: 2010 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392010000200007 |
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| Alfaro,Marta; Salazar,Francisco; Iraira,Sergio; Teuber,Nolberto; Villarroel,Dagoberto; Ramírez,Luis. |
| In Chile there is little information on nutrient losses in livestock systems. The experiment was carried out between 2004 and 2006. Two stocking rates (3.5 and 5.0 steers ha-1) were tested under rotational grazing with Black and White Friesian steers on a permanent pasture (67.5 kg N and 40 kg P ha-1 yr-1). To quantify surface runoff losses (N, P, K), three surface lysimeters (5 x 5 m) per treatment were established. N and K leaching losses were estimated with ceramic cups. Runoff and leachate samples were individually analyzed for available and total N, reactive (RP) and total P, and K. Dissolved organic N (DON) and organic P (OP) were estimated as the difference between total and available forms. The stocking rate did not increase total N, P and K losses... |
| Tipo: Journal article |
Palavras-chave: Eutrofication; Water quality; Grazing; Andisol; Beef production. |
| Ano: 2008 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392008000200004 |
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| Alfaro,Marta; Salazar,Francisco. |
| In developed countries, intensive grazing has been related to water pollution. The results of several projects carried out on a volcanic soil of the Osorno soil series on beef grazing production systems have shown that grazing management did not increase total nitrogen (N) and phosphorus (P) transfer and losses. Due to the high water infiltration capacity of the soil, runoff was <1% of total drainage, therefore, N and P losses in runoff were small. Nitrogen leaching losses were high (3 up to 71 kg N ha-1 yr-1). Nitrogen loss in runoff was mainly lost as DON (c. 50%) while N leaching losses were mainly as nitrate (c. 70%). Total P losses ranged between 1 and 22 g P ha-1 yr-1 and they increased with increasing field slopes. Phosphorus was mainly lost as... |
| Tipo: Journal article |
Palavras-chave: Nitrogen; Phosphorus; Dairy production; Beef production; Environmental impact. |
| Ano: 2008 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-27912008000200002 |
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