Efeitos de esterco bovino em atributos químicos e físicos do solo, produtividade de milho e créditos de nitrogênio
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2018-05-28
Autores
Silva, Marcio Silveira da
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Universidade Estadual Paulista (Unesp)
Resumo
O esterco bovino, além de fornecer nutrientes, quando utilizado repetidamente e/ou em grandes quantidades, pode melhorar outros atributos químicos e físicos do solo. Porém, um dos grandes desafios na sua utilização é estimar a quantidade de N que é fornecida durante o ciclo das culturas. Os objetivos com este trabalho foram determinar as alterações nos atributos químicos e físicos do solo, a produtividade de milho e os créditos de nitrogênio derivados da aplicação de esterco bovino e de seu efeito residual. Para alcançá-los foram conduzidos, simultaneamente, dois experimentos, no município de Jaboticabal-SP, em Latossolo Vermelho eutroférrico muito argiloso, durante os anos agrícolas 2011/12; 2012/13; 2013/14 e 2014/15. Ambos os experimentos foram conduzidos em blocos casualizados com quatro repetições. Um dos experimentos foi conduzido para determinar a curva de resposta da cultura do milho ao N, e por meio desta calcular os créditos de nitrogênio provenientes da aplicação do esterco. Para isso, foram aplicadas as doses 0, 60, 90, 120, 180 e 240 kg ha-1 de N-ureia. No outro experimento foram avaliados os efeitos no solo e na planta da aplicação de 0, 5, 10, 15, 30, 45 e 60 Mg ha-1 de esterco bovino e de seu efeito residual, sendo a aplicação do adubo realizada apenas nos dois primeiros anos. Houve melhoria nos atributos químicos do solo pela aplicação de esterco bovino, e a duração dos efeitos foi variável, de modo que para os nutrientes (P, Ca2+, Mg2+ e K+) houve efeito residual e para as variáveis relativas à acidez do solo (pH e H+Al) o efeito não persistiu após a interrupção da aplicação. O teor de carbono orgânico do solo aumentou linearmente com o aumento das doses de esterco, o que levou ao aumento no diâmetro médio dos agregados e na macroporosidade, e diminuição na densidade, mesmo após a interrupção da aplicação do esterco por dois anos e em solo manejado de forma mecânica anualmente. A aplicação de até 60 Mg ha-1 de esterco bovino durante dois anos consecutivos propiciou aumentos na produtividade de grãos de milho nos dois anos de aplicação e nos dois anos de avaliação do efeito residual, sendo que a produtividade média nos anos de aplicação de esterco foi 59% maior. Os créditos de N devidos à aplicação de esterco bovino variaram de 5 a 122 kg ha-1 de N considerando aplicação e efeito residual do adubo e os maiores créditos foram obtidos com a aplicação de 30, 45, 60 e 60 Mg ha-1, respectivamente no primeiro, segundo, terceiro e quarto anos de avaliações.
The use of cattle manure, in addition to providing nutrients, when used repeatedly and/or in large quantities, can improve other chemical and physical attributes of the soil. However, one of the major challenges in its use is to estimate the amount of N that is supplied during the crop cycle. The aims of the trials were to evaluate the changes in soil chemical and physical attributes, corn yield and nitrogen credits from the application of cattle manure and its residual effect. In this perspective, two experiments were conducted, simultaneously, in the municipality of Jaboticabal-SP, in an Typic Eutrudox, during the crop seasons 2011/12; 2012/13; 2013/14 and 2014/15. Both trials were conducted in a randomized block with four replicates. One of the trials was conducted to determine the response curve of the corn crop to the N, and through this calculate the nitrogen credits from the application of manure. Rates of 0; 60; 90; 120; 180 and 240 kg ha-1 N-urea. In the other trial, the effects on the soil and on plant of the application of 0, 5, 10, 15, 30, 45 and 60 Mg ha1 of cattle manure and its residual effect were evaluated, applying the fertilizer only in the two first years. There was an enhancement in the chemical attributes of the soil by the application of cattle manure, and the continuance of the effects was variable, so that nutrients (P, Ca2+, Mg2+ and K+ ) had a residual effect and for the variables related to soil acidity (pH and H+ Al) the effect did not persist after the application interruption. The organic carbon content of the soil increased linearly as the rates of manure were increased, which led to the increase in the mean weight diameter of the aggregates and the macroporosity, and decrease in the bulk density, even after the interruption of the application of manure for two years and in a soil plowed annually. The application of up to 60 Mg ha-1 of cattle manure during two consecutive years resulted in increases in grain yield of corn in the two years of application and in the two years of evaluation of the residual effect, and the average yield in the period of application of manure was 59% higher. The N credits due to the application of cattle manure ranged from 5 to 122 kg ha-1 of N considering the application and residual effect of the fertilizer and the highest credits were obtained with the application of 30, 45, 60 and 60 Mg ha-1 , respectively in the first, second, third and fourth years of evaluations.
The use of cattle manure, in addition to providing nutrients, when used repeatedly and/or in large quantities, can improve other chemical and physical attributes of the soil. However, one of the major challenges in its use is to estimate the amount of N that is supplied during the crop cycle. The aims of the trials were to evaluate the changes in soil chemical and physical attributes, corn yield and nitrogen credits from the application of cattle manure and its residual effect. In this perspective, two experiments were conducted, simultaneously, in the municipality of Jaboticabal-SP, in an Typic Eutrudox, during the crop seasons 2011/12; 2012/13; 2013/14 and 2014/15. Both trials were conducted in a randomized block with four replicates. One of the trials was conducted to determine the response curve of the corn crop to the N, and through this calculate the nitrogen credits from the application of manure. Rates of 0; 60; 90; 120; 180 and 240 kg ha-1 N-urea. In the other trial, the effects on the soil and on plant of the application of 0, 5, 10, 15, 30, 45 and 60 Mg ha1 of cattle manure and its residual effect were evaluated, applying the fertilizer only in the two first years. There was an enhancement in the chemical attributes of the soil by the application of cattle manure, and the continuance of the effects was variable, so that nutrients (P, Ca2+, Mg2+ and K+ ) had a residual effect and for the variables related to soil acidity (pH and H+ Al) the effect did not persist after the application interruption. The organic carbon content of the soil increased linearly as the rates of manure were increased, which led to the increase in the mean weight diameter of the aggregates and the macroporosity, and decrease in the bulk density, even after the interruption of the application of manure for two years and in a soil plowed annually. The application of up to 60 Mg ha-1 of cattle manure during two consecutive years resulted in increases in grain yield of corn in the two years of application and in the two years of evaluation of the residual effect, and the average yield in the period of application of manure was 59% higher. The N credits due to the application of cattle manure ranged from 5 to 122 kg ha-1 of N considering the application and residual effect of the fertilizer and the highest credits were obtained with the application of 30, 45, 60 and 60 Mg ha-1 , respectively in the first, second, third and fourth years of evaluations.
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Palavras-chave
Adubação nitrogenada, Adubo orgânico, Carbono orgânico do solo, Zea mays (L.), Valor de substituição do nitrogênio, Nitrogen fertilization, Organic fertilizer, Soil organic carbon, Nitrogen fertilizer replacement value