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Anais da Escola Superior de Agricultura Luiz de Queiroz

Print version ISSN 0071-1276

An. Esc. Super. Agric. Luiz de Queiroz vol.18  Piracicaba  1961 

A disponibilidade do fósforo de oiversos fosfatos estudada por meio do método de Neubauer"



R. A. Catani; N. A. da Glória

E. S A. "Luiz de Queiroz"




In order to study the phosphorus availability from various phosphates fertilizers an experiment was performed according to the biological seedling method of Neubauer. The physico-chemical properties of the soil "terra roxa-misturada", a red soil derived from basaltic rocks are given in the Portuguese text. Rice (Oryza sativa, L.) instead of rye (Secale cereale, L.) was used.
Five replications of each of the following treatments were made:
1 - check, with 350 g of sand
2 - 350 g of sand plus 100 g of soil
3 - 350 g of sand and plus 100 g of soil plus 40 mg of P2O5, from superphosphate.
4 - 350 g of sand plus 100 g of soil plus 40 mg of P2O5. from Olinda (Brazil) phosphorite.
5 - 350 g of sand plus 100 g of soil plus 40 mg of P2O5 from Florida (U. S. A.) phosphorite.
6 - 350 g os sand plus 100 g of soil plus 40 mg of P2O5 from Hyperphosphate, a commertial name of a North African (Gafsa) phosphorite.
7 - 350 g of sand plus 100 g of soil plus 40 mg of P2O5 from Araxá (Brazil) apatite.
After 18 days of growth, the roots and tops of rice seedlings were harvested and analysed for phosphorus, and the results are summarized in table 1.

Table 1 - Milligrams of P2O5 determined in rice seedlings.

Treatments             Mean of 5 replications mg of P2O5

1 .....................                       24.196

2 .....................                      23.850

3 .....................                      30.724

4 .....................                      27.620

5 .....................                      27.480

6.....................                      30.210

7 .....................                      26.032

The least significant difference at the 5% level by Tukey's procedure for comparisons among the treatments means is 1.365 mg of P20.
It is interesting to observe that rice plants did not take any phosphorus from the soil according to he data of the treatments n.° 1 and n.° 2. This can be explained by the high phosphorus fixing capacity of the soil "terra roxa misturada".



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CATANI, R. A. & J. E. PAIVA NETTO, 1950 - O método Neubauer aplicado ao estudo do potássio nos solos do Estado de São Paulo. Bragantia, 10: 27-32.         [ Links ]

CATANI, R. A. & H. GARGANTINI, 1954 - Extração do fósforo do solo pelo método de Neubauer e por métodos químicos. Bra-gantia, 13: 55 - 62.         [ Links ]

CATANI, R. A. & H.BERGGAMIN FILHO, 1960 - A fixação do fósforo pela terra roxa misturada estudada pelo método Neubauer e com o auxílio do fósforo radioativo P...,. Revista tia Agricultura, 35: 161 - 172.         [ Links ]

NEUBAUER, H. & W. SCHNEIDER, 1923 - Die Náhrstoffaufnahme der Keimpflanzen und ihre Anwendung auf die Bestimmung des Nãhrstoffgehalts der Bõden. Zeitsch. f. Pflazenernàhrung und Düngung. 2A: 329 - 362.         [ Links ]

PELLEGRINO, D. 1960 - A determinação do fósforo pelo método do ácido fosfovanadomolíbdico. Escola Superior de Agricultura "Luiz de Queiroz". Piracicaba. 58 pp. (Tese),         [ Links ]

PIMENTEL GOMES, F., 1960 -- Curso de Estatística Experimental Editora Gráfica Supertipo Ltda. São Paulo. 229 pp.         [ Links ]

STEEL, R. D. & J. H. TORRIE, 1960 - Principles and Procedures of Statistics. McGraw - Hill Book Co. N. York. 481 pp.         [ Links ]

VANDECAVEYE, S- C, 1948 - Biological methods of determining nutrients in soil. Em Kitchen, H. B., ed. Diagnostic techniques for soils and crops. Washington, American Potash Institute, pp. 199 - 230.         [ Links ]



Recebido para publicação em 24/7/1961.

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