Adubação nitrogenada com inibidor de urease e nitrificação em capim-tifton 85
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2017-04-28
Autores
Soares, Edimar Rodrigues [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O nitrogênio é um nutriente altamente móvel e dinâmico no solo, passível de perdas por diferentes processos, como volatilização, lixiviação e desnitrificação. Inibidores de urease ou de nitrificação são tecnologias que podem aumentar a eficiência da adubação nitrogenada, porém, a utilização destes produtos é pouco estudada em regiões tropicais. Foram realizados dois experimentos com o objetivo de avaliar (I): em condições de campo, o crescimento e a produção de capimtifton 85 em função de doses de nitrogênio com ureia contendo inibidor de urease e de nitrificação conduzido por dois anos agrícolas (2013/14 e 2014/15), no período de novembro a março, com quatro ciclos de crescimentos em cada ano; (II): a nitrificação do nitrogênio com ureia recoberta com doses de folha ou torta de nim, utilizando o DMPP para comparação. Os tratamentos do experimento I foram constituídos por um esquema fatorial 3 x 5, com ureia; ureia + inibidor de urease (NBPT - N-butil tiamida fosfórico) e ureia + inibidor de nitrificação (DMPP - Fosfato de 3,4-dimetilpirazol) e doses de N (0, 40, 80, 120 e 160 kg ha-1, em cada crescimento). No segundo ano agrícola, foram feitas avaliações de crescimento aos 10, 20 e 30 dias após a aplicação dos adubos. No experimento II, os tratamentos foram constituídos de um esquema fatorial 2 x 4 + 2, com o primeiro fator representado por fontes de nim (folha e torta de nim), utilizadas para recobrir a ureia e o segundo fator de doses de nim, sendo estas doses de 0, 10, 20 e 40% do total de N aplicado (200 mg kg-1, utilizando como fonte de N a ureia) e dois tratamentos adicionais: testemunha (solo sem fertilizante nitrogenado) e ureia + DMPP. As doses de N aumentaram a área foliar, índice de área foliar e altura da planta, todavia não houve efeito do tipo de adubo nestas características. No décimo dia do primeiro crescimento, verificou-se que a adubação nitrogenada aumentou linearmente o perfilhamento. No 20o dia ocorreram morte de perfilhos em função das maiores doses de N aplicadas, havendo no trigésimo dia redução linear do perfilhamento em função das doses de N. A utilização de ureia + NBPT e ureia + DMPP não aumentou significativamente a produção do capim-tifton 85 nos dois anos agrícolas, comparada a ureia comum. No primeiro ano agrícola não foi observado efeito das doses de N, tão pouco do tipo de adubo na recuperação aparente de N. A utilização de ureia com inibidor de urease ou de nitrificação não interfere no crescimento e na produção do capim-tifton 85. No experimento II, o recobrimento da ureia com folha e torta de nim foi eficiente em reduzir os teores de nitrato no solo até os 15 dias de incubação. Isso resultou em maiores teores de amônio no solo até 15 dias. Todavia, o DMPP mostrou-se mais eficiente em reduzir a nitrificação, promovendo inibição até os 60 dias de incubação.
Nitrogen is a highly dynamic and mobile nutrient that may undergo losses through different processes, such as volatilization, leaching and denitrification. Urease or nitrification inhibitors are technologies that may improve nitrogen fertilization efficiency; however, usage of these products is little studied in tropical regions. Two experiments were conducted aiming to evaluate: (I) growth and production of tifton 85 grass on field conditions according to nitrogen doses with urea containing urease and nitrification inhibitor for two agricultural years (2013/14 and 2014/15), from November through March, each year with four cycles of growth; (II) nitrogen nitrification with urea covered with doses of powdered neem leaves or neem seed cakes, using DMPP for comparison. Treatments in experiment I were build up on a 3 x 5 factorial scheme with urea; urea + urease inhibitor [NBPT: N-(N-Butyl) thiophosphoric triamide] and urea + nitrification inhibitor (DMPP: 3,4-dimethyl pyrazole phosphate) and doses of N (0, 40, 80, 120 and 160 kg ha-1, in each growth). On the second agricultural year, growth evaluations were performed on the 10th, 20th and 30th days after the application of fertilizers. In the experiment II, the treatments consisted of a 2 x 4 + 2 factorial scheme, with the first factor represented neem leaves or neem seed cakes sources, used to cover urea and the second neem dose factor, being these doses of 0, 10, 20 and 40% of the total N applied (200 mg kg-1, using urea N as the source) and two additional treatments: control (soil without nitrogen fertilizer) and urea + DMPP. N doses increased leaf area, leaf area indexes and height, but there was no effect due to the type of fertilizer in this scenario. On the tenth day of the first growth, it was verified that nitrogen fertilization increased tillers linearly. On the 20th day, there was tiller death due to greater doses of N applied, with linear reduction of tiller on the 30th day. The usage of urea + NBPT and urea + DMPP did not influence the production of tifton 85 grass in the two agricultural years. On the first year, an actual effect from doses of N was not observed, neither from the type of fertilizer on the apparent N recovering. The usage of urea with urease or nitrification inhibitor does not interfere in the production and growth of tifton 85 grass. In experiment II, the covering of urea with powdered neem leaves and neem seed cakes was efficient in reducing the proportions of nitrate within the soil up to 15 days of incubation. This resulted in greater proportions of ammonium within the soil up to 15 days. However, DMPP revealed to be more efficient in reducing nitrification, promoting inhibition through the 60 days of incubation.
Nitrogen is a highly dynamic and mobile nutrient that may undergo losses through different processes, such as volatilization, leaching and denitrification. Urease or nitrification inhibitors are technologies that may improve nitrogen fertilization efficiency; however, usage of these products is little studied in tropical regions. Two experiments were conducted aiming to evaluate: (I) growth and production of tifton 85 grass on field conditions according to nitrogen doses with urea containing urease and nitrification inhibitor for two agricultural years (2013/14 and 2014/15), from November through March, each year with four cycles of growth; (II) nitrogen nitrification with urea covered with doses of powdered neem leaves or neem seed cakes, using DMPP for comparison. Treatments in experiment I were build up on a 3 x 5 factorial scheme with urea; urea + urease inhibitor [NBPT: N-(N-Butyl) thiophosphoric triamide] and urea + nitrification inhibitor (DMPP: 3,4-dimethyl pyrazole phosphate) and doses of N (0, 40, 80, 120 and 160 kg ha-1, in each growth). On the second agricultural year, growth evaluations were performed on the 10th, 20th and 30th days after the application of fertilizers. In the experiment II, the treatments consisted of a 2 x 4 + 2 factorial scheme, with the first factor represented neem leaves or neem seed cakes sources, used to cover urea and the second neem dose factor, being these doses of 0, 10, 20 and 40% of the total N applied (200 mg kg-1, using urea N as the source) and two additional treatments: control (soil without nitrogen fertilizer) and urea + DMPP. N doses increased leaf area, leaf area indexes and height, but there was no effect due to the type of fertilizer in this scenario. On the tenth day of the first growth, it was verified that nitrogen fertilization increased tillers linearly. On the 20th day, there was tiller death due to greater doses of N applied, with linear reduction of tiller on the 30th day. The usage of urea + NBPT and urea + DMPP did not influence the production of tifton 85 grass in the two agricultural years. On the first year, an actual effect from doses of N was not observed, neither from the type of fertilizer on the apparent N recovering. The usage of urea with urease or nitrification inhibitor does not interfere in the production and growth of tifton 85 grass. In experiment II, the covering of urea with powdered neem leaves and neem seed cakes was efficient in reducing the proportions of nitrate within the soil up to 15 days of incubation. This resulted in greater proportions of ammonium within the soil up to 15 days. However, DMPP revealed to be more efficient in reducing nitrification, promoting inhibition through the 60 days of incubation.
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Palavras-chave
Ureia, Fertilizantes estabilizados, Cynodon spp.