Availability of the potassium of nephéline sienite from Poços de Caldas, evaluated through successive croppings with corn

• Autor(a) principal: Siqueira, J. O.
• Data de Publicação: 2014
• Outros Autores: Guedes, Geraldo A.A., Ribeiro, Marco A.V.
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Pesquisa Agropecuária Brasileira (Online)
• Texto Completo: https://seer.sct.embrapa.br/index.php/pab/article/view/15124
• topic: potassium rock; dry matter; potassium fertilizer; rocha potássica; matéria seca; fertilizante potássico

The availability of K of the potassium rock (nepheline sienite) from Poços de Caldas was studied under greenhouse conditions through successive croppings using corn plants grown in Dark Red Latossol (DRL) and "Terra Roxa Estruturada" (TRE) in presence and absence of liming. Addition of KCl showed significant effects on dry matter yields, regardless of liming. This response was linear and higher in LVE than in TRE. KCl doses greater than 200 ppm of K reduced dry matter production in TRE. After the first cropping, dry matter yields were drastically reduced and this seems to be due to the depletion of available K in 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 in 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 in 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.