Effect of water and citrate solubility on agronomic effectiveness of acidulated phosphates in three consecutive corn crops

Efeito da solubilidade em água e em citrato de fosfatos acidulados na eficiência agronômica para três cultivos sucessivos de milho

SEÇÃO VIII - FERTILIZANTES E CORRETIVOS

Effect of water and citrate solubility on agronomic effectiveness of acidulated phosphates in three consecutive corn crops(¹)

Efeito da solubilidade em água e em citrato de fosfatos acidulados na eficiência agronômica para três cultivos sucessivos de milho

L. I. Prochnow^I; B. van Raij^II; J. C. Kiehl^I

^IDoctor Professor of the Department of Soil and Plant Nutrition, University of São Paulo - USP, Escola Superior de Agricultura "Luiz de Queiroz" - ESALQ. Caixa Postal 9, CEP 13418-900 Piracicaba (SP). E-mail: [e-mail]

^IIPesquisador da Embrapa Meio Ambiente. Caixa Postal 69, CEP 13820-000 Jaguariúna (SP)

ABSTRACT

In the process of phosphate rock acidulation, several impure P compounds may be formed along with the desirable Ca and NH₄ phosphates. Such compounds normally reduce the content of water-soluble P and thus the agronomic effectiveness of commercial fertilizers. In order to study this problem, a greenhouse experiment consisting of three consecutive corn crops was conducted in samples of a Red-Yellow Latosol (Typical Hapludox) in a completely randomized design (6 x 2 x 2), with four replicates. Six commercial fertilizers were added to 2 kg of soil at a rate of 70 mg kg^-1 P, based on the content of soluble P in neutral ammonium citrate plus water (NAC + H₂O) of the fertilizers. Fertilizer application occurred either in the original form or leached to remove the water-soluble fraction, either by mixing the fertilizer with the whole soil in the pots or with only 1 % of its volume. The corn plants were harvested 40 days after emergence to determine the shoot dry matter and accumulated P. For the first crop and localized application, the elimination of water-soluble P from the original fertilizers resulted in less bioavailable P for the plants. For the second and third crops, the effects of P source, leaching and application methods were not as evident as for the first, suggesting that the tested P sources may have similar efficiencies when considering successive cropping. The conclusion was drawn that the water-insoluble but NAC-soluble fractions of commercial P fertilizers are not necessarily inert because they can provide P in the long run.

Index-terms: water-soluble P, water-insoluble P, acidulated P fertilizers, maize.

RESUMO

No processo de acidulação de fosfato de rocha, vários compostos classificados como impuros podem ser obtidos paralelamente aos fosfatos de cálcio e de amônio. Tais compostos normalmente reduzem o teor de P solúvel em água e a eficiência agronômica dos fertilizantes. Com o objetivo de estudar este problema, desenvolveu-se um experimento em casa de vegetação; três cultivos sucessivos de milho foram feitos em amostras de um Latossolo Vermelho-Amarelo em esquema fatorial completo (6 x 2 x 2), com quatro repetições. Seis fertilizantes fosfatados acidulados comerciais foram adicionados a 2 kg de solo na dose de 70 mg kg^-1 de P, a qual foi determinada de acordo com o teor de P solúvel em citrato neutro de amônio + água (CNA + H₂O) dos fertilizantes. Os fertilizantes foram aplicados na forma original ou lavados para remover a fração de fósforo solúvel em água e incorporados em volume total de terra ou com 1 % do volume. As plantas de milho foram colhidas após 40 dias da emergência e a matéria seca e P acumulado foram determinados. No primeiro cultivo, e aplicação localizada, a eliminação do P solúvel em água dos fertilizantes originais resultou em menor quantidade de P biodisponível às plantas. Nos demais cultivos, os efeitos de fonte de fósforo, lavagem e método de aplicação não foram tão evidentes como no primeiro cultivo, sugerindo que as fontes de P testadas podem ter eficiência semelhante quando se consideram vários cultivos. Concluiu-se que a fração insolúvel em água, porém solúvel em CNA, dos fertilizantes testados não deve ser vista como totalmente inerte, uma vez que pode disponibilizar fósforo a longo prazo.

Termos de indexação: P solúvel em água, P insolúvel em água, fertilizantes fosfatados acidulados, milho.

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ACKNOWLEDGMENTS

The authors wish to express their gratitude to Dr. Norman Chien, from the International Fertilizer Development Center, for the relevant opinions and review, which certainly improved the quality of this paper. The first author wishes also to express his gratitude to CNPq for his scholarship in research.

LITERATURE CITED

Received for publication in july of 2000

Approved in april of 2002

• ASSOCIATION OF OFFICIAL ANALYTICAL CHEMISTS - AOAC. Official methods of analysis. 14.ed. Arlington, 1984.
• BARTOS, J.M.; MULLINS, G.L; SIKORA, F.G. & COPELAND, J.P. Availability of phosphorus in the water-insoluble fraction of monoammonium phosphate fertilizers. Soil Sci. Soc. Am. J., 55:539-543, 1991.
• BARTOS, J.M.; MULLINS, G.L.; WILLIANS, J.C.; SIKORA, F.J. & COPELAND, J.P. Water-insoluble impurity effects on phosphorus availability in monoammonium phosphate fertilizers. Soil Sci. Soc. Am. J., 56:972-976, 1992.
• CATHCART, J.B. World phosphate reserves and resources. In: KHASAWNEH, F.E.; SAMPLE, E.C. & KAMPRATH, E.J., eds. The role of phosphorus in agriculture. Madison, American Society of Agronomy, 1980. p.1-18.
• DILLARD, E.F. & FRAZIER, A.E. Precipitated impurities in monoammonium phosphate and their effect on chemical and physical properties of suspension fertilizers. Muscle Shoals, Alabama, National Fertilizer Development Center, 1983. 57p.
• FRAZIER, A.W. & LEHR, J.R. Iron and aluminum compounds in commercial superphosphates. J. Agr. Food Chem., 15:348-349, 1967.
• GILKES, R.J. & LIM-NUNEZ, R. Poorly soluble phosphates in Australian superphosphate: their nature and availability to plants. Aust. J. Soil Res., 18:85-95, 1980.
• GILKES, R.J. & MANGANO, P. Poorly soluble, iron-aluminum phosphates in ammonium phosphate fertilizers: their nature and availability to plants. Aust J. Soil Res. 21:183-194, 1983.
• HAMMOND, L.L.; CHIEN, S.H.; ROY, A.H. & MOKWUNYE, A.U. Solubility and agronomic effectiveness of partially acidulated phosphate rocks as influenced by their iron and aluminum oxide contents. Fert. Res., 19:93-98, 1989.
• LEHR, J.R. Impact of phosphate rock quality on fertilizer market uses. Ind. Miner., 200:127-153, 1984.
• LEHR, J.R. Phosphate raw materials and fertilizers, Part I - a look ahead. In: KHASAWNEH, F.E.; SAMPLE, E.C. & KAMPRATH, E.J., eds. The role of phosphorus in agriculture. Madison, American Society of Agronomy, 1980. p.81-120.
• LEHR, J.R.; FRAZIER, A.W. & SMITH, J.P. Precipitated impurities in wet-process phosphoric acid. J. Agr. Food Chem., 14:27-33, 1966.
• MALAVOLTA, E.; VITTI, G.C. & OLIVEIRA, S.A. Avaliação do estado nutricional das plantas, princípios e aplicações. Piracicaba, Associação Brasileira da Pesquisa Potassa e Fosfato, 1989. 201p.
• MCCLELLAN, G.H. & GREMILLION, L.R. Evaluation of phosphatic raw materials. In: KHASAWNEH, F.E.; SAMPLE, E.C. & KAMPRATH, E.J., eds. The role of phosphorus in agriculture. Madison, American Society of Agronomy, 1980. p.43-80.
• MULLINS, G.L. Plant availability of P in commercial superphosphate fertilizers. Comm. Soil Sci. Plant Anal., 19:1509-1525, 1988.
• MULLINS, G.L. & SIKORA, F.J. Effect of soil pH on the requirement for water-soluble phosphorus in triple superphosphate fertilizers. Fert. Res., 40:207-214, 1995.
• MULLINS, G.L.; SIKORA, F.J. &. WILLIANS, J.C. Effect of water-soluble phosphorus on the effectiveness of triple superphosphate fertilizers. Soil Sci. Soc. Am. J., 59:256-260, 1995.
• PROCHNOW, L.I.; KIEHL, J.C. & RAIJ, B. van. Influence of cationic impurities in acidulated phosphates on the availability of phosphorus to two corn crops. Comm. Soil Sci. Plant Anal., 28:1375-1391, 1997.
• PROCHNOW, L.I.; KIEHL, J.C. & RAIJ, B. van. Plant availability of phosphorus in the neutral ammonium citrate fraction of Brazilian acidulated phosphates. Nutr. Cyc. Agric., 52:61-65, 1998.
• RAIJ, B. van & QUAGGIO, J.A. Métodos de análise de solo para fins de fertilidade. Campinas, Instituto Agronômico de Campinas, 1983. 31p.
• SINDEN, J. MFM-magnesium multiphosphate. Phosph. Potassium, 167:20-25, 1990.
• SIKORA, F.J.; DILLARD, E.J.; COPELAND, J.P. & MULLINS, G.L. Chemical characterization and bioavailability of phosphorus in water-insoluble fractions of three monoammonium phosphate fertilizers. J. Association Off. Anal. Chem., 72:852-856, 1989.
• SIKORA, F.J.; COPELAND, J.P. & MULLINS, G.L. Apparent solubility products of phosphorus impurity compounds in commercial monoammonium phosphate fertilizers. Soil Sci. Soc. Am. J., 56:402-407, 1992.

(1

) Part of the Ph.D. Thesis of the first author presented to the University of São Paulo - USP.

Publication Dates

• Publication in this collection
  30 Sept 2014
• Date of issue
  Sept 2002

History

• Received
  July 2000
• Accepted
  Apr 2002