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Abstract(s)
O nitrogênio (N) é o nutriente que maior impacta a produtividade das culturas e aquele que é utilizado em maior quantidade na cultura do milho. Contudo, o mesmo está suscetível a perdas por diversos fenômenos, como volatilização de amônia, lixiviação de nitratos e desnitrificação. Estas perdas podem ascender a mais de 30 a 50% do N aplicado como fertilizante. O presente estudo tem por objetivo avaliar o efeito de fertilizantes que liberam os nutrientes de forma gradual para as plantas nas propriedades do solo, em particular na dinâmica do N, no crescimento e produtividade da cultura do milho e na eficiência do uso de N. O experimento foi conduzido na Quinta do Poulão em Bragança, com delineamento experimental completamente casualizado. Os tratamentos fertilizantes utilizados foram: um fertilizante mineral (nitrato de amônio, 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 ha1; um corretivo orgânico (estrume de vaca) em uma dose correspondente à aplicação de 100 kg N ha-1; e uma modalidade testemunha sem fertilização. Para cada tratamento foram incluidas 3 repetições. Foram realizadas avaliações sobre o estado nutricional das plantas através dos indicadores NDVI e SPAD, bem como da concentração de nutrientes nas folhas. No final do ciclo vegetativo foi avaliada a produtividade de forragem, o teor de nitrato nos caules (Stalk Nitrate Test) e a exportação de nutrientes. Foi avaliado ainda o teor de N mineral no solo em précobertura (PSNT, Pre-sidedress Soil Nitrate Test). Os resultados encontrados no teste de nitratos no solo e do nitrogênio mineral mostraram que quanto maior a dose de N aplicada, maior o risco de perdas de N através de lixiviação, desnitrificação e erosão. A produtividade apresentou efeito positivo ao aumento das doses de N aplicado comparado à modalidade testemunha. A maior produtividade foi encontrada no tratamento com fertilizante estabilizado, na dose de 200 kg ha-1, porém, os fertilizantes de liberação gradual não apresentaram diferença significativa para o fertilizante mineral convencional. A fertilização com corretivo orgânico não apresentou benefício significativo nos parâmetros avaliados.
Nitrogen (N) is the nutrient that has the greatest impact on crops growth and the one used in larger amounts in maize crop. However, it is susceptible to cause several environmental impacts, through ammonia volatilization, nitrate leaching and denitrification. These phenomena can be responsible for the loss of more than 30 to 50% of the N applied as a fertilizer. The present study aims to evaluate the effect of fertilizers that gradually release nutrients to plants on soil properties, in particular those related to N availability, and on maize growth and N use efficiency. The experiment was conducted at Quinta do Poulão in Bragança, as a completely randomized design. The fertilizer treatments were: a mineral fertilizer (ammonium nitrate, 27% N) in three doses (50, 100 and 200 kg N ha-1); a NPK controlled-release compound fertilizer and a stabilized fertilizer with a nitrification inhibitor, both at doses of 100 and 200 kg N ha-1; an organic amendment (cow manure) in a dose corresponding to the application of 100 kg N ha-1; and a control treatment without fertilization. For each treatment, 3 replications were used. Assessments of the nutritional status of plants were carried out using NDVI and SPAD indicators, as well as leaf nutrient concentration. At the end of the growing season, the forage yield, the nitrate content in the stems (Stalk Nitrate Test) and the removal of nutrients were evaluated. The mineral N content in the soil at pre-sidedress (PSNT, Pre-sidedress Soil Nitrate Test) was also evaluated. The results found in the test of nitrates in the soil and of the mineral N, showed that the higher the doses of N applied, the greater the risk of losses of N through leaching, denitrification and erosion. The productivity showed a positive effect to the increase in the doses of N applied compared to the control treatment. The highest productivity was found in the treatment with stabilized fertilizers, at a dose of 200 kg ha-1, however, the gradual release fertilizers did not show any significant difference for the conventional mineral fertilizer. Organic fertilization did not show significant benefits in the evaluated parameters.
Nitrogen (N) is the nutrient that has the greatest impact on crops growth and the one used in larger amounts in maize crop. However, it is susceptible to cause several environmental impacts, through ammonia volatilization, nitrate leaching and denitrification. These phenomena can be responsible for the loss of more than 30 to 50% of the N applied as a fertilizer. The present study aims to evaluate the effect of fertilizers that gradually release nutrients to plants on soil properties, in particular those related to N availability, and on maize growth and N use efficiency. The experiment was conducted at Quinta do Poulão in Bragança, as a completely randomized design. The fertilizer treatments were: a mineral fertilizer (ammonium nitrate, 27% N) in three doses (50, 100 and 200 kg N ha-1); a NPK controlled-release compound fertilizer and a stabilized fertilizer with a nitrification inhibitor, both at doses of 100 and 200 kg N ha-1; an organic amendment (cow manure) in a dose corresponding to the application of 100 kg N ha-1; and a control treatment without fertilization. For each treatment, 3 replications were used. Assessments of the nutritional status of plants were carried out using NDVI and SPAD indicators, as well as leaf nutrient concentration. At the end of the growing season, the forage yield, the nitrate content in the stems (Stalk Nitrate Test) and the removal of nutrients were evaluated. The mineral N content in the soil at pre-sidedress (PSNT, Pre-sidedress Soil Nitrate Test) was also evaluated. The results found in the test of nitrates in the soil and of the mineral N, showed that the higher the doses of N applied, the greater the risk of losses of N through leaching, denitrification and erosion. The productivity showed a positive effect to the increase in the doses of N applied compared to the control treatment. The highest productivity was found in the treatment with stabilized fertilizers, at a dose of 200 kg ha-1, however, the gradual release fertilizers did not show any significant difference for the conventional mineral fertilizer. Organic fertilization did not show significant benefits in the evaluated parameters.
Description
Mestrado de dupla diplomação com a UTFPR - Universidade Tecnológica Federal do Paraná
Keywords
Zea mays Fertilizantes de liberação lenta Fertilizantes estabilizados Fertilizantes de liberação controlada Corretivo orgânico Nitratos no solo em pré-cobertura Nitratos no caule