Adubação nitrogenada e perdas de N-NH3 de fontes convencionais e de eficiência aumentada na cultura do milho
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Data
2018-10-19
Autores
Souza, Juscelio Ramos
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Universidade Estadual Paulista (Unesp)
Resumo
Os fertilizantes nitrogenados são essenciais para as culturas sob condições tropicais expressarem seus potenciais produtivos. Dentre esses fertilizantes a ureia é o mais utilizado na agricultura e devido à necessidade de redução de suas perdas por volatilização quando aplicada na superfície do solo, a ureia tornou-se o fertilizante convencional mais utilizado para o desenvolvimento de fertilizantes de eficiência aumentada. Atualmente substâncias inibidoras da enzima urease e mecanismos de revestimento de fertilizantes que alterem o fluxo de liberação de N para solução do solo, podem reduzir as perdas de N por volatilização da NH3. O trabalho foi dividido em dois estudos, com os seguintes objetivos: avaliar em condições controladas de laboratório fontes de nitrogênio convencionais e de eficiência aumentada, quanto ao controle de perdas de N por volatilização de NH3 e em um segundo estudo avaliar a eficiência de fontes e doses de nitrogênio convencionais e de eficiência aumentada em cobertura no desempenho agronômico da cultura do milho, cultivado na primeira e segunda safras 2015/2016. No experimento de laboratório, os fertilizantes utilizados foram aplicados na superfície de um latossolo vermelho argiloso, previamente umedecido a 60% da capacidade de retenção de água. Conduzido em delineamento inteiramente ao acaso com seis repetições, os tratamentos foram quatro fontes de N (ureia, ureia + NBPT, nitrato de amônio e Haya® - ureia compactada com aditivos e polímeros), além de controles adicionais (solo sem fertilizante e câmara vazia) em dose equivalente a 100 kg ha-1 de N. Foram avaliadas as perdas de N-NH3 por volatilização por um período de 20 dias com o auxílio de câmaras hermeticamente fechadas. Ao final do experimento, após 20 dias da aplicação dos fertilizantes, o tratamento com ureia perdeu 43% do N aplicado, em quanto a ureia + NBPT e o Haya® reduziram as perdas de amônia em 81 e 77% respectivamente quando comparadas com a ureia comercial, surgindo como fontes promissoras para aumentar a eficiência da aplicação de nitrogênio sob condições tropicais. Os experimentos de campo foram conduzidos em um latossolo vermelho eutrófico, no delineamento em blocos casualizados com quatro repetições. Os tratamentos foram distribuídos em esquema fatorial 3x3+1, utilizando-se três fontes de N (ureia, nitrato de amônio e Haya® - ureia compactada com aditivos e polímeros) e três doses de N (70, 140 e 210 kg ha-1) e um tratamento adicional, sem adubação nitrogenada aplicadas em cobertura. O aumento das doses de N aplicadas em cobertura promoveu acréscimos no desempenho agronômico da cultura do milho em ambas safras. As produtividades máximas de grãos obtidas na primeira safra foram de 12.297, 12.088 e 9.473 kg ha-1, quando utilizado as fontes Haya®, nitrato de amônio e a ureia, nas doses de 161, 168 e 195 kg ha-1 de N, respectivamente. Na primeira e segunda safras, a ureia compactada com aditivos e polímeros e o nitrato de amônio proporcionaram maior eficiência agronômica, contudo, as maiores eficiências ocorreram na dose de 70 kg ha-1, independentemente da fonte de N e das safras.
Nitrogen fertilizers are essential for crops under tropical conditions express their productive potential. Among these fertilizers urea is the most widely used in agriculture and due to the need to reduce their losses by volatilization when applied on the soil surface, the urea has become the conventional fertilizer most used for the development of enhanced efficiency fertilizers. Currently urease enzyme inhibitory substances and coating mechanisms of fertilizers that alter the flow of release of N to the soil solution, can reduce N losses by volatilization of NH3. The work was divided in two studies, with the following objectives: to evaluate under controlled conditions of laboratory conventional nitrogen sources and increased efficiency, how to control N losses by volatilization of NH3 and a second study evaluate the efficiency of sources and doses of conventional nitrogen and increased efficiency in coverage on agronomic performance of the culture of corn, cultivated in the first and second harvests 2015/2016. In the laboratory experiment, fertilizers used were applied on the surface of a red loamy latosol, previously moistened the 60% water holding capacity. Conducted in entirely random design with six repetitions, the treatments were four sources of N (urea, urea + ammonium nitrate and NBPT Haya® urea compressed with additives and polymers), plus additional controls (without soil and fertilizer Chamber empty) in dose equivalent to 100 kg ha-1 of N losses were evaluated-NH3 volatilization for a period of 20 days with the aid of hermetically sealed Chambers. At the end of the experiment, after 20 days the application of fertilizers, urea treatment lost 43% of the N applied, in how much urea + NBPT and Haya® reduced ammonia losses in 81 and 77% respectively when compared with the commercial urea, emerging as promising sources to increase the efficiency of nitrogen application under tropical conditions. The field experiments were conducted in a Eutrophic red latosol, in randomized block design with four replications. The treatments were distributed in 3 x 3 factorial scheme +1, using three sources of N (urea, ammonium nitrate and Haya®-urea packed with additives and polymers) and three doses of N (70, 140 and 210 kg ha-1) and an additional treatment, no nitrogen fertilization applied in coverage. Increasing the doses of N applied in agronomic performance Extras promoted coverage of culture of corn in both crops. The maximum grain yields obtained in the first crop were 12,297, 12,088 and 9,473 kg ha-1 when used the Haya® sources, ammonium nitrate and urea, in doses of 161, 168 and 195 kg ha-1 N, respectively. In the first and second crops, urea packed with additives and polymers and the ammonium nitrate provide greater efficacy, however, the greatest efficiencies occurred at a dose of 70 kg ha-1, regardless of the source of N and of harvests.
Nitrogen fertilizers are essential for crops under tropical conditions express their productive potential. Among these fertilizers urea is the most widely used in agriculture and due to the need to reduce their losses by volatilization when applied on the soil surface, the urea has become the conventional fertilizer most used for the development of enhanced efficiency fertilizers. Currently urease enzyme inhibitory substances and coating mechanisms of fertilizers that alter the flow of release of N to the soil solution, can reduce N losses by volatilization of NH3. The work was divided in two studies, with the following objectives: to evaluate under controlled conditions of laboratory conventional nitrogen sources and increased efficiency, how to control N losses by volatilization of NH3 and a second study evaluate the efficiency of sources and doses of conventional nitrogen and increased efficiency in coverage on agronomic performance of the culture of corn, cultivated in the first and second harvests 2015/2016. In the laboratory experiment, fertilizers used were applied on the surface of a red loamy latosol, previously moistened the 60% water holding capacity. Conducted in entirely random design with six repetitions, the treatments were four sources of N (urea, urea + ammonium nitrate and NBPT Haya® urea compressed with additives and polymers), plus additional controls (without soil and fertilizer Chamber empty) in dose equivalent to 100 kg ha-1 of N losses were evaluated-NH3 volatilization for a period of 20 days with the aid of hermetically sealed Chambers. At the end of the experiment, after 20 days the application of fertilizers, urea treatment lost 43% of the N applied, in how much urea + NBPT and Haya® reduced ammonia losses in 81 and 77% respectively when compared with the commercial urea, emerging as promising sources to increase the efficiency of nitrogen application under tropical conditions. The field experiments were conducted in a Eutrophic red latosol, in randomized block design with four replications. The treatments were distributed in 3 x 3 factorial scheme +1, using three sources of N (urea, ammonium nitrate and Haya®-urea packed with additives and polymers) and three doses of N (70, 140 and 210 kg ha-1) and an additional treatment, no nitrogen fertilization applied in coverage. Increasing the doses of N applied in agronomic performance Extras promoted coverage of culture of corn in both crops. The maximum grain yields obtained in the first crop were 12,297, 12,088 and 9,473 kg ha-1 when used the Haya® sources, ammonium nitrate and urea, in doses of 161, 168 and 195 kg ha-1 N, respectively. In the first and second crops, urea packed with additives and polymers and the ammonium nitrate provide greater efficacy, however, the greatest efficiencies occurred at a dose of 70 kg ha-1, regardless of the source of N and of harvests.
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Palavras-chave
Manejo da adubação nitrogenada, Produtividade de grãos, Urease, Nitrogen fertilizer management, Grain productivity