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Abstract(s)
O nitrogênio é o nutriente mais determinante na produtividade das culturas e aquele que é utilizado em maior quantidade na cultura do milho. Contudo, fenômenos como volatilização de amônia e lixiviação e desnitrificação de nitratos podem causar perdas de 30 a 50% do nitrogênio utilizado como fertilizante, o que impulsiona pesquisas por novos fertilizantes que liberem os nutrientes de forma gradual, tentando assegurar um fornecimento mais regular dos nutrientes às plantas durante o seu ciclo vegetativo e reduzir o número de aplicações. O objetivo deste estudo é avaliar o efeito de fertilizantes que liberam os nutrientes de forma gradual para as plantas no crescimento e produtividade da cultura do milho e na dinâmica do nitrogênio e em algumas propriedades do solo. Foram conduzidos ensaios na área experimental do Instituto Politécnico de Bragança, com delineamento experimental completamente causalizado. Os tratamentos fertilizantes utilizados foram: um fertilizante mineral (nitrato de amónio, 27 %N) em três doses (50, 100 e 200 kg N ha-1); um fertilizante composto NPK de liberação controlada e um fertilizante estabilizado com um inibidor da nitrificação, ambos nas doses de 100 e 200 kg N ha-1; um corretivo orgânico (estrume de vaca) em uma dose correspondente à aplicação de 100 kg N ha-1; e uma modalidade testemunha sem fertilização. De cada tratamento foram incluídas três repetições. Foi avaliado o estado nutricional das plantas através de análise foliar e o teor de nitrogênio mineral no solo em pré-cobertura (PSNT, Pre-sidedress Soil Nitrate Test). Na colheita foi avaliada a produtividade de forragem, o teor de nitratos nos caules (Stalk Nitrate Test) e a exportação de nutrientes. Após a colheita foi avaliado o nitrogênio mineral residual e o nitrogênio potencialmente mineralizável e demais propriedades do solo. O pH do solo se mostrou baixo em todos os tratamentos e houve uma diminuição no valor com a elevada aplicação de nitrogênio e para os adubos de liberação gradual. A relação dos valores do teste aos nitratos no solo em pré-cobertura e do nitrogênio mineral residual no fim da estação de crescimento mostrou que o corretivo orgânico e os tratamentos com doses elevadas de nitrogênio apresentam maiores riscos de perdas de nitrogênio com a chegada das chuvas de outono. Este resultado foi corroborado com o teor de nitratos nos caules. Na produtividade registaram-se aumentos significativos nas modalidades fertilizadas em comparação com a modalidade testemunha. Os fertilizantes com mecanismos de liberação gradual não mostraram benefícios significativos em comparação com o fertilizante mineral convencional.
Nitrogen is the most determinant nutrient in crop productivity and the one that is used in greater amounts in maize crop. However, phenomena such as ammonia volatilization, nitrate leaching and denitrification can cause losses of 30 to 50% of the nitrogen applied as a fertilizer, which drives researches for new fertilizers that release nutrients gradually, trying to ensure a more regular supply of nutrients to the plants during the growing season and the reduction of the number of fertilizer applications. The objective of this study was to evaluate the effect of fertilizers that release nutrients gradually to the plants on the growth and yield of maize and on soil nitrogen dynamic and several other soil properties. A field trial was conducted in an experimental plot of the Polytechnic Institute of Bragança, arranged in a completely randomized design. The fertilizer treatments used were: mineral fertilizer (ammonium nitrate, 27% N) in three rates (50, 100 and 200 kg N ha-1); a controlled-release NPK fertilizer and a stabilized fertilizer with a nitrification inhibitor, both in the rates of 100 and 200 kg N ha-1; an organic amendment (cow manure) at a rate corresponding to the application of 100 kg N ha-1; and a control treatment without nitrogen application. Three replicates were included of each treatment. The nutritional status of the plants was evaluated through leaf analysis and soil mineral nitrogen content using the pre-sidedress soil nitrate test (PSNT). At the harvest, forage yield, stalk nitrate concentration (Stalk Nitrate Test) and nutrients removal in the aboveground biomass were assessed. After the harvest, the residual mineral nitrogen, potentially mineralizable nitrogen and other soil properties were also determined. Soil pH decreased as the rate of nitrogen applied increased, the same result was observed with gradual-release mechanism fertilizers. The results of PSNT and residual mineral nitrogen at the end of the growing season suggest that the use of organic amendments and high nitrogen rates present a higher risk of nitrogen losses following the autumn rains. This result was corroborated by the stalk nitrate test. Dry matter yield significantly increased in all fertilized treatment in comparison to control. Controlled-release and stabilized fertilizers did not show benefits compared to the conventional mineral fertilizer.
Nitrogen is the most determinant nutrient in crop productivity and the one that is used in greater amounts in maize crop. However, phenomena such as ammonia volatilization, nitrate leaching and denitrification can cause losses of 30 to 50% of the nitrogen applied as a fertilizer, which drives researches for new fertilizers that release nutrients gradually, trying to ensure a more regular supply of nutrients to the plants during the growing season and the reduction of the number of fertilizer applications. The objective of this study was to evaluate the effect of fertilizers that release nutrients gradually to the plants on the growth and yield of maize and on soil nitrogen dynamic and several other soil properties. A field trial was conducted in an experimental plot of the Polytechnic Institute of Bragança, arranged in a completely randomized design. The fertilizer treatments used were: mineral fertilizer (ammonium nitrate, 27% N) in three rates (50, 100 and 200 kg N ha-1); a controlled-release NPK fertilizer and a stabilized fertilizer with a nitrification inhibitor, both in the rates of 100 and 200 kg N ha-1; an organic amendment (cow manure) at a rate corresponding to the application of 100 kg N ha-1; and a control treatment without nitrogen application. Three replicates were included of each treatment. The nutritional status of the plants was evaluated through leaf analysis and soil mineral nitrogen content using the pre-sidedress soil nitrate test (PSNT). At the harvest, forage yield, stalk nitrate concentration (Stalk Nitrate Test) and nutrients removal in the aboveground biomass were assessed. After the harvest, the residual mineral nitrogen, potentially mineralizable nitrogen and other soil properties were also determined. Soil pH decreased as the rate of nitrogen applied increased, the same result was observed with gradual-release mechanism fertilizers. The results of PSNT and residual mineral nitrogen at the end of the growing season suggest that the use of organic amendments and high nitrogen rates present a higher risk of nitrogen losses following the autumn rains. This result was corroborated by the stalk nitrate test. Dry matter yield significantly increased in all fertilized treatment in comparison to control. Controlled-release and stabilized fertilizers did not show benefits compared to the conventional mineral fertilizer.
Description
Dupla diplomação com a UTFPR - Universidade Tecnológica Federal do Paraná
Keywords
Zea Mays Fertilizantes de liberação lenta Fertilizantes de liberação controlada Fertilizantes estabilizados Corretivos orgânicos Presidedress soil nitrate test