Competição entre adubos fosfatados em milho (Zea mays L)

Malavolta, E.; Coury, T.; Ranzani, G.; Catani, R. A.; Sobr., M.O. C. Brasil; Arruda, Hermano Vaz de

doi:10.1590/s0071-12761953000100009

Cited by 2 publications

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“…Studies in Brazil have shown that P from Araxa rock phosphate is much less available than P from superphosphate when equal amounts of P are applied (Malavolta et al, 1953;Viegas et al, 1960). This n:sult would be expected because of the low citric acid solubility of Araxa rock phosphate.…”

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confidence: 99%

Availability of Rock Phosphate as Measured by an Acid Tolerant Pasture Grass and Extractable Phosphorus¹

Yost¹,

Naderman²,

Kamprath³

et al. 1982

Agronomy Journal

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As agricultural development intensifies in tropical countries and as costs of superphosphate production increase, the need for further evaluation of rock phosphates has become apparent. An acid tolerant pasture grass (Brachiaria decumbens Stapf.) was used to evaluate the initial and residual (3 years) availability of P from several phosphate materials. A field study was conducted on a Typic Haplustox of the Cerrado of Central Brazil. Initial availability of P supplied as normal superphosphate, Hyperphosphate, Thermalphosphate, and North Carolina rock phosphate was similar when the soils were not limed (pH = 4.3, Al = 1.4 meq/100g). Where lime had been added and pH was increased to 5.4 the P in Hyperphosphate and N.C. rock phosphate was initially less available than P added as superphosphate and Thermalphosphate. After 10 months of contact, lime no longer significantly depressed P availability in these relatively soluble rock phosphates as measured by forage dry weight. The P in the other phosphate rock of low citric acid solubility, Araxá, was virtually unavailable during the 3 months after application. However, within 13 months, maximum forage yields were attained where this material had been applied to unlimed soil and at 25 months maximum yields were obtained on both limed and unlimed soil. Higher rates of Araxá material were required to obtain maximum yields than with normal superphosphate. Forage yields were 2 to 4 times greater where superphosphate was surface applied each year than where similar amounts were incorporated prior to planting. A comparison of extractant methods for soil P indicated that highly acidic extractants (e.g., 0.05 N HC1 + 0.025 N H2SO4) overestimated available P where rock phosphate had been applied. Where superphosphate or rock phosphate had been applied, P availability was better assessed by extractants such as 0.5 M NaHCO3 and Bray 1. The results emphasize the need to supplement laboratory and short‐term studies with long‐term evaluations of P materials with acid tolerant perennial crop species available in tropical countries.

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confidence: 99%

Availability of Rock Phosphate as Measured by an Acid Tolerant Pasture Grass and Extractable Phosphorus¹

Yost¹,

Naderman²,

Kamprath³

et al. 1982

Agronomy Journal

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Adubação do milho: XI - Efeito residual do fósforo

Viégas¹,

Freire

1958

Bragantia

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Como contribuição para o conhecimento do efeito residual do fósforo nos solos do Estado de São Paulo os autores apresentam os resultados de dois ensaios com milho, um conduzido em terra-roxa-misturada (Campinas) e o outro em solo arenoso claro (Ipanema). Em ambos o efeito em aprêço foi muito grande, sendo que em Campinas o do superfosfato se mostrou igual, e, em Ipanema, superior ao dos fosfatos menos solúveis. Mesmo examinando êsses resultados em conjunto com os de várias outras experiências que resumiram, acham os autores que ainda não se podem estabelecer, para cada tipo de solo, relações numéricas entre os efeitos residuais dos adubos estudados. Concluem, porém, que tanto nos solos claros como nos vermelhos ou na terra-roxa, geralmente é grande o efeito residual do fósforo, seja êle aplicado na forma de superfosfato ou na de outros fosfatos de uso corrente na agricultura paulista. Por fim, lembram a possibilidade de reduzirem-se substancialmente as doses de fósforo a serem aplicadas nos solos que já o receberam nas culturas anteriores, sugerindo que se estude experimentalmente a redução a ser feita em cada caso.

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Competição entre adubos fosfatados em milho (Zea mays L)

Cited by 2 publications

References 1 publication

Availability of Rock Phosphate as Measured by an Acid Tolerant Pasture Grass and Extractable Phosphorus¹

Availability of Rock Phosphate as Measured by an Acid Tolerant Pasture Grass and Extractable Phosphorus¹

Adubação do milho: XI - Efeito residual do fósforo

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Competição entre adubos fosfatados em milho (Zea mays L)

Cited by 2 publications

References 1 publication

Availability of Rock Phosphate as Measured by an Acid Tolerant Pasture Grass and Extractable Phosphorus1

Availability of Rock Phosphate as Measured by an Acid Tolerant Pasture Grass and Extractable Phosphorus1

Adubação do milho: XI - Efeito residual do fósforo

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Availability of Rock Phosphate as Measured by an Acid Tolerant Pasture Grass and Extractable Phosphorus¹

Availability of Rock Phosphate as Measured by an Acid Tolerant Pasture Grass and Extractable Phosphorus¹