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Abstract(s)
Com vista a reduzir a contaminação ambiental associada ao uso de fertilizantes
convencionais foram desenvolvidos os adubos que libertam os nutrientes de forma
gradual, tentando assegurar um fornecimento mais regular de azoto às plantas durante o
seu ciclo vegetativo, reduzindo o número de aplicações e restringindo as perdas de
azoto.
Os objectivos gerais do trabalho passaram por avaliar os efeitos dos fertilizantes
de libertação gradual na produção de biomassa de um relvado municipal.
Simultaneamente foram monitorizados os teores de azoto nítrico no solo ao longo da
estação de crescimento, bem como as modificações ocorridas na composição florística
do relvado.
Este trabalho decorreu num relvado do Município de Valpaços no ano de 2008.
Foram implementados os seguintes tratamentos: Floranid permanent 16:7:15 (adubo de
libertação lenta, IBDU/Isodur); Basacote plus 9M 16:8:12 (adubo de libertação
controlada, copolímero etlileno acrílico); Nitroteck 20:8:10 (fertilizante estabilizado,
DCD como inibidor da nitrificação + revestimento de politerpeno); Nitrolusal (20,5%
N); e uma modalidade testemunha sem azoto. Os fertilizantes foram aplicados em dose
equivalente a 120 kg N ha-1 em 11 de Março de 2008. O Nitrolusal foi fraccionado em
duas aplicações, sendo a segunda metade aplicada em 10 de Julho. Atendendo às
diferentes composições dos adubos em macronutrientes, as doses de fósforo e potássio
foram ajustadas com superfosfato 18% e cloreto de potássio, tornando-as equivalentes
em todos os tratamentos. Para avaliar o desenvolvimento do relvado foram feitos cortes
sequenciais desde Abril a Setembro. Com base na biomassa obtida foi determinado o
azoto exportado. O teor de nitratos no solo foi monitorizado usando membranas de troca
aniónica enterradas directamente no solo. Em Outubro foi avaliada a dinâmica da
vegetação por comparação da matéria seca das componentes gramíneas e trifoliadas.
A matéria seca produzida foi significativamente superior no Floranid, Nitroteck
e Nitrolusal em relação a Basacote, tendo este fertilizante produzido matéria seca
significativamente superior à testemunha. Contudo, o azoto exportado no Basacote não
foi inferior aos restantes fertilizantes. Através do teor de nitratos nos extractos confirmou-se que o Basacote disponibilizou mais azoto nas fases mais avançadas do
ciclo. O azoto libertado em fase avançada do ciclo teve menor influência na matéria
seca produzida, mas aumentou a concentração de azoto nas plantas nos últimos cortes.
A maior disponibilidade de azoto no talhão do Basacote na fase avançada da estação de
crescimento favoreceu a componente gramínea em detrimento da leguminosa. Resultado
semelhante ocorreu com Nitrolusal devido ao seu fraccionamento. Os índices de
eficiência económica foram favoráveis a Nitroteck e desfavoráveis a Basacote, devido à grande diferença nos preços.
In order to reduce environmental contamination from the use of fertilizers, it has appeared on the market a range of fertilizers that release nutrients gradually, trying to ensure a more regular supply of nitrogen to the plants during the growing season and, at the same time, reduce the number of applications and limit nitrogen losses. The general objectives of this study were the evaluation of the effects of slowrelease fertilizer in the production of biomass of a municipal turf grass. In addition soil nitrate nitrogen content was monitored during the growing season, being also the changes in floristic composition of the turf recorded. The field experiment was carried out in the growing season of 2008, in the gardens of the city of Valpaços. Five fertilizer treatments were established: Floranid permanent 16-7-15 (slow-release, IBDU/Isodur fertiliser); Basacote plus 9M 16-8-12 (controlled-release fertiliser, copolymer ethylene acrylic); Nitroteck 20-8-10 (stabilized fertiliser, DCD as nitrification inhibitor + coating with polyterpene); Nitrolusal (ammonium nitrate, 20.5% N); and a zero N control. The fertilizers were applied in doses equivalent to 120 kg N ha-1 on March 11th. Nitrolusal rate was split into two applications. The levels of phosphorus and potassium were adjusted with 18% superphosphate and potassium chloride. Sequential cuts were made to determine the production of dry matter and nitrogen recovered. The soil nitrates levels were checked by using anionic exchange membranes, buried in the soil. In October, the vegetation’s status was evaluated by comparing the dry matter of the trifoliate and grass components. Dry matter yield was significantly higher with Floranid, Nitroteck and Nitrolusal than with Basacote, having this fertilizer produced significantly greater dry matter than the control treatment. However, nitrogen recovered in Basacote was not lower than that in the other fertilized plots. Through the level of nitrate in the extracts, it has been confirmed that the Basacote released more nitrogen in the advanced stages of the growing season. The nitrogen released later had less influence on dry matter yield, but increased the concentration of nitrogen in plants in latest cuts. The increased availability of nitrogen in the plot of the Basacote as the growing season progressed favored the grass component. Similar result was obtained with Nitrolusal due to its fractionation. The economic efficiency index was favorable to Nitroteck and unfavorable to Basacote due to the large differences in their prices.
In order to reduce environmental contamination from the use of fertilizers, it has appeared on the market a range of fertilizers that release nutrients gradually, trying to ensure a more regular supply of nitrogen to the plants during the growing season and, at the same time, reduce the number of applications and limit nitrogen losses. The general objectives of this study were the evaluation of the effects of slowrelease fertilizer in the production of biomass of a municipal turf grass. In addition soil nitrate nitrogen content was monitored during the growing season, being also the changes in floristic composition of the turf recorded. The field experiment was carried out in the growing season of 2008, in the gardens of the city of Valpaços. Five fertilizer treatments were established: Floranid permanent 16-7-15 (slow-release, IBDU/Isodur fertiliser); Basacote plus 9M 16-8-12 (controlled-release fertiliser, copolymer ethylene acrylic); Nitroteck 20-8-10 (stabilized fertiliser, DCD as nitrification inhibitor + coating with polyterpene); Nitrolusal (ammonium nitrate, 20.5% N); and a zero N control. The fertilizers were applied in doses equivalent to 120 kg N ha-1 on March 11th. Nitrolusal rate was split into two applications. The levels of phosphorus and potassium were adjusted with 18% superphosphate and potassium chloride. Sequential cuts were made to determine the production of dry matter and nitrogen recovered. The soil nitrates levels were checked by using anionic exchange membranes, buried in the soil. In October, the vegetation’s status was evaluated by comparing the dry matter of the trifoliate and grass components. Dry matter yield was significantly higher with Floranid, Nitroteck and Nitrolusal than with Basacote, having this fertilizer produced significantly greater dry matter than the control treatment. However, nitrogen recovered in Basacote was not lower than that in the other fertilized plots. Through the level of nitrate in the extracts, it has been confirmed that the Basacote released more nitrogen in the advanced stages of the growing season. The nitrogen released later had less influence on dry matter yield, but increased the concentration of nitrogen in plants in latest cuts. The increased availability of nitrogen in the plot of the Basacote as the growing season progressed favored the grass component. Similar result was obtained with Nitrolusal due to its fractionation. The economic efficiency index was favorable to Nitroteck and unfavorable to Basacote due to the large differences in their prices.
Description
Keywords
Azoto Fertilização azotada Eficiência de utilização do azoto Relvados
Citation
Magalhães, Paula Cristina da Rosa - Gestão de fertilizantes de libertação gradual de nutrientes em relvados municipais. Bragança: Instituto Politécnico, Escola Superior Agrária, 2009. Dissertação de Mestrado em Agroecologia
Publisher
Instituto Politécnico de Bragança, Escola Superior Agrária