adubos fosfatados na cultura da batata

1 - As experiências relatadas no presente trabalho se referem ao emprêgo de diferentes adubos fosfatados na cultura da batata (S. tuberosum L.) e conduzidas em Campinas, Taubaté e Joanópolis, em 1940 e 1944. 2 - As análises sumárias das terras indicaram variações do fósforo, desde muito fraco (Joanópolis), regular (Campinas) até ótimo (Taubaté) . 3 - As menores produções foram obtidas dos canteiros sem adubo. 4 - O emprêgo ùnicamente de adubos azotados mais potássicos, pràticamente, não determinou aumento de produção sôbre os "sem adubo". 5 - O acréscimo de adubos fosfatados aos azotados e potássicos causou um aumento altamente significativo de produção. 6 - Os canteiros em que além dos adubos azotados e potássicos, incluímos o Superfosfato apresentaram em todos os ensaios as melhores colheitas. 7 - Quanto aos demais adubos, pequenas foram as diferenças existentes.
The experiments herein reported deal mainly with the comparative effect of five sources of phosphate on the yield of the potato plant. The trials were carried out at three localities in the State of São Paulo, viz. : Campinas, Taubaté and Joanópolis. Soil analyses from the test plots showed variation in phosphorus content. This was low at Joanópolis, medium at Campinas, and high at Taubaté. Nitrogen was added as ammonium sulphate, nitrate of soda, and potassium nitrate ; potash, as potassium sulphate or potassium carbonate (ashes). Phosphorus was suplied by superphosphates (trade names of Dawco and Granulated, of American origin) by "Cibraphosphate", "Serranaphosphate" and "Serranaphosphatepotassico" from local manufacturers and by bone meal. All forms of nitrogen or potash tried were about equally effective for potatoes when applied with any of the phosphates. Phosphorus was found to be the most important element to increase production. Applications of only nitrogen plus potash, brought no significant increase in yield. The greatest yields were obtained with superphosphates in complete formulae. The other forms of phosphate fertilizers were better than the controls and the nitrogen plus potash treatments, but inferior to the superphosphates. The superiority of the superphosphates is ascribed to their greater solubility, which renders the phosphorus readily available to the potato plant.