| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 795.98 KB | Adobe PDF |
Authors
Advisor(s)
Abstract(s)
O trabalho experimental foi realizado na Quinta do Poulão, em Bragança, NE Portugal, no decorrer dos anos 2018 e 2019, com o objetivo de verificar a influência da adubação nitrogenada da cultura do milho na aveia, cultivada em sequência, e avaliar a capacidade da aveia na captura de nitrogênio (N) do solo, a fim de reduzir as perdas de nitratos para os cursos de água e óxidos de N para a atmosfera. A aveia, em si, não foi fertilizada. O ensaio com a aveia foi conduzido em dois delineamentos experimentais independentes. Um dos experimentos foi conduzido em delineamento experimental completamente casualizado, constituído por um fertilizante nitrogenado convencional, nitrato de amônio (27% N), usado em três doses, repartidas em aplicações de fundo e cobertura, 50 (25+25), 100 (50+50) e 200 (100+100) kg N ha-1, um fertilizante composto NPK de liberação controlada (12-10-18) e um fertilizante estabilizado com um inibidor da nitrificação (26% N), ambos usados nas doses de 100 e 200 kg N ha-1, um corretivo orgânico (estrume de vaca) usado em uma dose correspondente à aplicação de 100 kg N ha-1, com (100 kg N ha-1) e sem aplicação de N em cobertura e uma testemunha não fertilizada. O segundo experimento foi organizado em um fatorial completo usando condicionadores de solo, biochar, correspondente à aplicação de 10 t ha-1, e zeólitos, utilizado a uma taxa de 5 t ha-1, e o fator doses de N, que incluiu quatro doses do fertilizante mineral convencional (27% N) aplicadas metade em fundo e metade em cobertura na forma 0 (0 + 0), 50 (25 + 25), 100 (50 + 50) e 200 (100 + 100) kg N ha-1. Os resultados encontrados no primeiro experimento mostram que as maiores doses de N (200 kg ha-1) aplicadas à cultura do milho correspondem ao maior teor de N mineral residual no solo após a colheita, o que se refletiu nos indicadores de estado nutricional da aveia, SPAD e NDVI. E também, na produtividade da aveia, que foi mais elevada em N200 e Org100. À medida que houve incremento na produção de massa seca aumentou também a quantidade de N recuperado pela aveia. Devido ao cultivo da aveia ocorreu redução de até 87% do teor de N mineral residual no solo. No segundo experimento observou-se que os condicionadores aplicados antes da sementeira do milho influenciaram o teor de N mineral no solo em outubro após a colheita, sendo o fertilizante mineral o que apresentou menor teor de N mineral residual. No entanto, à medida que houve aumento nas doses de N aplicadas ocorreu também aumento do teor de N residual no solo. Com relação ao indicador de estado nutricional SPAD, os condicionadores não apresentaram efeito significativo. Já para o NDVI, o condicionador biochar mostrou os menores valores. Os condicionadores aplicados antes da semeadura do milho não apresentaram efeito significativo na produtividade e na quantidade de N recuperado pela aveia, sendo o biochar o que apresentou os menores valores e o fertilizante mineral os maiores. No entanto, é possível observar que com o aumento das doses de N houve aumento de N recuperado pela cultura, sem diferença significativa para a concentração de N no tecido. Da mesma maneira, pode se atribuir à aveia uma elevada capacidade em recuperar o N disponível no solo e eficiência na sua utilização para produção de biomassa, e aos condicionadores a capacidade de retenção do N e disponibilização para as culturas, uma vez ocorreu redução média de 82% do teor de N mineral residual no solo após a cultura da aveia. O aveia foi eficiente como cultura de captura de N residual do solo.
The experimental work was carried out in Quinta do Poulão, Bragança, NE Portugal, during the years 2018 and 2019, in order to assess the influence of the nitrogen (N) fertilization of the maize crop in the oat cultivated in sequence, and to evaluate the performance of oat in recovering residual N, avoiding the leaching of nitrates to the watercourses and the emission of N oxides to the atmosphere. Oat itself was not fertilized. The study was conducted in two independent experimental designs. One of the experiments was conducted in a completely randomized design, consisting of a conventional N fertilizer, ammonium nitrate (27% N), used in three rates, distributed as basal and topdressing applications 50 (25 + 25), 100 (50 + 50) and 200 (100 + 100) kg N ha-1, a controlled release NPK compound fertilizer (12-10-18) and a fertilizer stabilized with a nitrification inhibitor (26% N), both used in rates of 100 and 200 kg N ha-1, an organic manure (cow manure) used at a rate corresponding to the application of 100 kg N ha-1, with (100 kg N ha-1) or without N application as topdressing and an unfertilized control. The second experiment was organized in a complete factorial using soil conditioners, biochar, corresponding to the application of 10 t ha-1, and zeolites, used at a rate of 5 t ha-1, and the factor rate of N, which included 0 (0 + 0), 50 (25 + 25), 100 (50 + 50) and 200 (100 + 100) kg N ha-1 to be applied as basal and topdressing applications as ammonium nitrate (27% N). The results of the first experiment showed that the highest N rates (200 kg ha-1) applied to maize were related to the higher mineral N content in the soil after maize harvest. The result influenced the N nutritional status indices, SPAD and NDVI, of oat. Consequently, oat productivity was higher in N200 and Org100N in comparison to the less fertilized treatments. Since an increase in dry matter production occurred, the amount of N recovered by oats also increased. Due to the cultivation of oat, there was a reduction of up to 87% in the content of soil mineral N. In the second experiment, it was observed that the soil conditioners applied before maize sowing influenced the mineral N content in the soil in October after harvesting, and the mineral fertilizer treatments had the lowest results. However, as the rates of N increased, an increase in the residual N content also occurred. SPAD readings did not significantly vary among the soil conditioners. The NDVI values, however, were significantly lower in the plots that received the biochar. The conditioners applied to maize did not have a significant effect on the productivity and amount of N recovered by oats, with biochar presenting the lowest average values and the mineral fertilizer the highest. However, it was observed that with increasing rates of N there was an increase of N recovered by the catch crop, even though no significant difference were found on the concentration of N in the plant tissues. Oat showed high ability to recover residual N available in the soil using it efficiently in biomass production. Soil conditioners showed ability to immobilize temporarily N and releasing it to the crop, since there was a mean reduction of 82% of the mineral N content in the soil after oat cultivation. Oat seemed to be an efficient N catch crop.
The experimental work was carried out in Quinta do Poulão, Bragança, NE Portugal, during the years 2018 and 2019, in order to assess the influence of the nitrogen (N) fertilization of the maize crop in the oat cultivated in sequence, and to evaluate the performance of oat in recovering residual N, avoiding the leaching of nitrates to the watercourses and the emission of N oxides to the atmosphere. Oat itself was not fertilized. The study was conducted in two independent experimental designs. One of the experiments was conducted in a completely randomized design, consisting of a conventional N fertilizer, ammonium nitrate (27% N), used in three rates, distributed as basal and topdressing applications 50 (25 + 25), 100 (50 + 50) and 200 (100 + 100) kg N ha-1, a controlled release NPK compound fertilizer (12-10-18) and a fertilizer stabilized with a nitrification inhibitor (26% N), both used in rates of 100 and 200 kg N ha-1, an organic manure (cow manure) used at a rate corresponding to the application of 100 kg N ha-1, with (100 kg N ha-1) or without N application as topdressing and an unfertilized control. The second experiment was organized in a complete factorial using soil conditioners, biochar, corresponding to the application of 10 t ha-1, and zeolites, used at a rate of 5 t ha-1, and the factor rate of N, which included 0 (0 + 0), 50 (25 + 25), 100 (50 + 50) and 200 (100 + 100) kg N ha-1 to be applied as basal and topdressing applications as ammonium nitrate (27% N). The results of the first experiment showed that the highest N rates (200 kg ha-1) applied to maize were related to the higher mineral N content in the soil after maize harvest. The result influenced the N nutritional status indices, SPAD and NDVI, of oat. Consequently, oat productivity was higher in N200 and Org100N in comparison to the less fertilized treatments. Since an increase in dry matter production occurred, the amount of N recovered by oats also increased. Due to the cultivation of oat, there was a reduction of up to 87% in the content of soil mineral N. In the second experiment, it was observed that the soil conditioners applied before maize sowing influenced the mineral N content in the soil in October after harvesting, and the mineral fertilizer treatments had the lowest results. However, as the rates of N increased, an increase in the residual N content also occurred. SPAD readings did not significantly vary among the soil conditioners. The NDVI values, however, were significantly lower in the plots that received the biochar. The conditioners applied to maize did not have a significant effect on the productivity and amount of N recovered by oats, with biochar presenting the lowest average values and the mineral fertilizer the highest. However, it was observed that with increasing rates of N there was an increase of N recovered by the catch crop, even though no significant difference were found on the concentration of N in the plant tissues. Oat showed high ability to recover residual N available in the soil using it efficiently in biomass production. Soil conditioners showed ability to immobilize temporarily N and releasing it to the crop, since there was a mean reduction of 82% of the mineral N content in the soil after oat cultivation. Oat seemed to be an efficient N catch crop.
Description
Keywords
Avena sativa Cultura de captura Fertilizantes de liberação controlada Fertilizantes estabilizados Corretivos orgânicos Condicionadores de solo