Fósforo e potássio associados a enxofre, boro e zinco na adubação de manutenção de capim-marandu
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2019-02-28
Autores
Vieira, Maycon Amim
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Universidade Estadual Paulista (Unesp)
Resumo
Os principais problemas das pastagens brasileiras são a deficiência de fósforo, acidez alta, pouca utilização de fertilizantes, além de pouca adubação de manutenção. Com o objetivo de avaliar fósforo e potássio associados a enxofre, boro e zinco na adubação de manutenção de pastagem de Urochloa brizantha cultivar Marandu, foi conduzido um experimento em Argissolo Vermelho Amarelo distrófico, na área experimental da Faculdade de Ciências Agrárias e Tecnológicas, UNESP, Campus de Dracena. O delineamento experimental foi em bloco casualizados, com quatro repetições. Em todos os tratamentos foram aplicados 120 kg ha-1 de N, na forma de nitrato de amônio, a qual foi dividida em quatro doses iguais, na semeadura e após os três cortes subsequentes. Os tratamentos foram os seguintes: T1) Controle - sem adubação, exceto N; T2) PK via fosfato monoamônio (MAP) e cloreto de potássio (KCl); T3) PKS via superfosfato simples (SS) e KCl; T4) PKS via S15 e KCl; T5) PKSB via S15 e KB; T6) PKSZn via SZ e KCl; T7) PKSBZn via SZ e KB; T8) PKSBZn via SZ, KB e Oxisulfato Zn. Nos tratamentos com PK foi aplicada a dose de 80 kg ha-1 de P2O5 e 50 kg ha-1 de K2O, respectivamente. As doses de enxofre, boro e zinco foram proporcionais a concentração na formulação de cada fertilizante, exceto o tratamento oito no qual foi acrescido o oxisulfato de Zn para fornecer o dobro do micronutriente em relação ao tratamento sete. MAP: (11%N, 52%P2O5); KCl: (60%K2O); SS (21%P2O5, 12%S); S15: (13% N, 33%P2O5, 15%S); KB: (58%K2O, 0,5%B); SZ: (12%N, 32%P2O5, 15%S, 1%Zn). Os resultados evidenciaram que a ausência de potássio reduziu a produção de massa verde, assim como a aplicação de fósforo, potássio, enxofre, boro e zinco na manutenção, não interferiu na produção de massa seca do capim Marandu. A aplicação de fósforo, potássio, enxofre, boro e zinco não influenciaram na porcentagem de lâminas foliares e na composição bromatológica do capim Marandu. Na camada de 0-0,2 m do solo, foi possível constatar o incremento na disponibilidade de fósforo, potássio, enxofre e zinco. Após dois anos de adubação aumentou a disponibilidade de potássio, enxofre, boro e zinco, na camada 0,2 – 0,4 m em relação a análise de solo inicial. No período das águas, a maior concentração de fósforo, potássio, enxofre e zinco na parte aérea do capim-marandu foi observado nos tratamentos que receberam a aplicação dos nutrientes via fertilizante mineral. De acordo com os resultados deste trabalho, para uma boa produção de massa verde, basta ter a presença do fósforo e potássio na adubação de manutenção. A produção de massa seca, porcentagem de lâminas foliares e qualidade bromatológica não foi afetada pela presença ou ausência, de fósforo, potássio, enxofre, boro e zinco. o tratamento que contém fósforo, potássio, enxofre, boro e zinco simultaneamente apresentou melhores resultados nos atributos químicos do solo e na concentração de nutrientes na parte aérea, contribuindo para a melhoria da fertilidade do solo e do desenvolvimento da planta.
The main problems of the Brazilian pastures are the deficiency of phosphorus, high acidity, little use of fertilizers, and little maintenance fertilization. With the objective of evaluating phosphorus and potassium associated to sulfur, boron and zinc in the pasture maintenance fertilization of Urochloa brizantha cultivar Marandu, an experiment was carried out in a dystrophic Ultisol in the experimental area of the Faculty of Agrarian and Technological Sciences, UNESP, Campus of Dracena. The experimental design was randomized block, with four replicates. In all treatments, 120 kg ha-1 of N, as ammonium nitrate, was applied, which was divided into four equal doses at sowing and after three subsequent cuts. The treatments were as follows: T1) Control - without fertilization, except N; T2) PK via monoammonium phosphate (MAP) and potassium chloride (KCl); T3) PKS via single superphosphate (SS) and KCl; T4) PKS via S15 and KCl; T5) PKSB via S15 and KB; T6) PKSZn via SZ and KCl; T7) PKSBZn via SZ and KB; T8) PKSBZn via SZ, KB and Oxisulfate Zn. In the treatments with PK the dose of 80 kg ha-1 of P2O5 and 50 kg ha-1 of K2O was applied, respectively. The sulfur, boron and zinc doses were proportional to the concentration in the formulation of each fertilizer, except treatment eight in which Zn oxysulphate was added to provide twice the micronutrient over treatment seven. MAP: (11% N, 52% P2O5); KCl: (60% K2O); SS (21%P2O5, 12%S); S15: (13%N, 33%P2O5, 15%S); KB: (58%K2O, 0.5%B); SZ: (12%N, 32%P2O5, 15%S, 1%Zn). The results evidenced that the absence of potassium reduced the green mass production, as well as the application of phosphorus, potassium, sulfur, boron and zinc in the maintenance, did not interfere in the production of dry mass of the Marandu grass. The application of phosphorus, potassium, sulfur, boron and zinc did not influence the percentage of leaf blades and the bromatological composition of Marandu grass. In the 0-0.2 m layer of the soil, it was possible to verify the increase in the availability of phosphorus, potassium, sulfur and zinc. After two years of fertilization increased the availability of potassium, sulfur, boron and zinc in the layer 0.2 - 0.4 m in relation to the initial soil analysis. In the period of the waters, the highest concentration of phosphorus, potassium, sulfur and zinc in the aerial part of the marandu grass was observed in the treatments that received the application of the nutrients via mineral fertilizer. According to the results of this work, for a good production of green mass, it is sufficient to have the presence of phosphorus and potassium in maintenance fertilization. The production of dry mass, percentage of leaf blades and bromatological quality was not affected by the presence or absence of phosphorus, potassium, sulfur, boron and zinc. the treatments containing phosphorus, potassium, sulfur, boron and zinc simultaneously showed better results in soil chemical attributes and nutrient concentration in the aerial part, contributing to the improvement of soil fertility and plant development.
The main problems of the Brazilian pastures are the deficiency of phosphorus, high acidity, little use of fertilizers, and little maintenance fertilization. With the objective of evaluating phosphorus and potassium associated to sulfur, boron and zinc in the pasture maintenance fertilization of Urochloa brizantha cultivar Marandu, an experiment was carried out in a dystrophic Ultisol in the experimental area of the Faculty of Agrarian and Technological Sciences, UNESP, Campus of Dracena. The experimental design was randomized block, with four replicates. In all treatments, 120 kg ha-1 of N, as ammonium nitrate, was applied, which was divided into four equal doses at sowing and after three subsequent cuts. The treatments were as follows: T1) Control - without fertilization, except N; T2) PK via monoammonium phosphate (MAP) and potassium chloride (KCl); T3) PKS via single superphosphate (SS) and KCl; T4) PKS via S15 and KCl; T5) PKSB via S15 and KB; T6) PKSZn via SZ and KCl; T7) PKSBZn via SZ and KB; T8) PKSBZn via SZ, KB and Oxisulfate Zn. In the treatments with PK the dose of 80 kg ha-1 of P2O5 and 50 kg ha-1 of K2O was applied, respectively. The sulfur, boron and zinc doses were proportional to the concentration in the formulation of each fertilizer, except treatment eight in which Zn oxysulphate was added to provide twice the micronutrient over treatment seven. MAP: (11% N, 52% P2O5); KCl: (60% K2O); SS (21%P2O5, 12%S); S15: (13%N, 33%P2O5, 15%S); KB: (58%K2O, 0.5%B); SZ: (12%N, 32%P2O5, 15%S, 1%Zn). The results evidenced that the absence of potassium reduced the green mass production, as well as the application of phosphorus, potassium, sulfur, boron and zinc in the maintenance, did not interfere in the production of dry mass of the Marandu grass. The application of phosphorus, potassium, sulfur, boron and zinc did not influence the percentage of leaf blades and the bromatological composition of Marandu grass. In the 0-0.2 m layer of the soil, it was possible to verify the increase in the availability of phosphorus, potassium, sulfur and zinc. After two years of fertilization increased the availability of potassium, sulfur, boron and zinc in the layer 0.2 - 0.4 m in relation to the initial soil analysis. In the period of the waters, the highest concentration of phosphorus, potassium, sulfur and zinc in the aerial part of the marandu grass was observed in the treatments that received the application of the nutrients via mineral fertilizer. According to the results of this work, for a good production of green mass, it is sufficient to have the presence of phosphorus and potassium in maintenance fertilization. The production of dry mass, percentage of leaf blades and bromatological quality was not affected by the presence or absence of phosphorus, potassium, sulfur, boron and zinc. the treatments containing phosphorus, potassium, sulfur, boron and zinc simultaneously showed better results in soil chemical attributes and nutrient concentration in the aerial part, contributing to the improvement of soil fertility and plant development.
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Palavras-chave
Macronutrientes, Matéria seca, Micronutrientes, Pastagem, Urochloa brizantha, Macronutrients, Dry matter, Micronutrients, Pasture, Urochloa brizantha