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Disponibilidade do potássio do sienito nefelínico de Poços de Caldas, avaliada em cultivos sucessivos com milho

1985; Embrapa Informação Tecnológica; Volume: 20; Issue: 3 Linguagem: Inglês

1678-3921

J. O. Siqueira, G. A. A. Guedes, Marco Aurélio Vitorino Ribeiro,

Growth and nutrition in plants

The availability of K of the potassium rock (nepheline sienite) from Pocos de Caldas was studied under greenhouse conditions through successive croppings using corn plants grown Dark Red Latossol (DRL) and Terra Roxa Estruturada (TRE) presence and absence of liming. Addition of KCl showed significant effects on dry matter yields, regardless of liming. This response was linear and higher LVE than TRE. KCl doses greater than 200 ppm of K reduced dry matter production TRE. After the first cropping, dry matter yields were drastically reduced and this seems to be due to the depletion of available K the soil. The potassium rock had little effect on corn growth, but when it was applied at rate of 300 ppm of K, significant positive response dry matter accumulation was found for DRL with liming. The reduced effect of this rock is due to its low K-supplying capacity even by the third cropping, as shown by the total K absorption by the plant. These data support earlier studies using chemical extractors the laboratory and show the low availability of the K from this rock to corn plants. It is suggested that potassium rock in natura can not be used as potassium source for corn.