Sôbre o efeito de dois fosfatos naturais
On the effect of two rock phosphates
G. P. Viégas; O. S. Neves; E. S. Freire * * Contratado pelo Conselho Nacional de Pesquisas, para colaborar com técnicos do Instituto Agronômico.
SUMMARY
The authors present the results obtained in a long-term experiment located at Campinas, State of São Paulo, on "terra-roxa-misturada" soil, in which two ground rock phosphates (apatite from Ipanema, São Paulo, and an Algerian phosphate) were compared with superphosphate in the presence of nitrogen and potash. The plots were successively cropped with various dops and received 60 kilograms of total P205 to the hectare per crop, except in the first and second applications of the natural phosphates, when only their contents of phosphoric soluble in 2% citric acid solution were considered. Accordingly, the doses of total P205 for each of those applications of Algerian phosphate and apatite were respectively of about 200 and 300 kilograms per hectare.
The response to phosphorus was generally very high. In the average of three crops-of corn and four of cotton, Algerian phosphate was equivalent to superphosphate, whereas the effect of apatite was about 60% of that of superphosphate. But the action of the phosphates changed appreciably in the course of the experiment. While superphosphate increased considerably the yields since the first year, Algerian phosphate was a little slower and apatite started showing its full effect only 3-4 years after the first application.
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Recebida para publicação em 15 de janeiro de 1960.
Datas de Publicação
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Publicação nesta coleção
14 Abr 2010 -
Data do Fascículo
1960
