Resumen

CHAVES, Lúcia H.G. et al. Use and management in the quantity/intensity ratio and adsorption of potassium in a Vertisol. Rev. de Ciências Agrárias [online]. 2019, vol.42, n.3, pp.41-50. ISSN 0871-018X.  https://doi.org/10.19084/rca.17516.

The availability of K for plants depends on the amount of exchangeable potassium (Q) and potassium in solution (I), and the Q/I ratio. The objective of this study was to evaluate the availability of K for crops using the Q / I curves and to adjust the Langmuir and Freundlich isotherms to K adsorption data in Vertisols. Samples of Vertisol were collected with natural tree vegetation (“forest”) and annual crops (“crop”) in two locations. K adsorption data on the samples were used to construct adsorption isotherms, obtaining the coefficients of the Freundlich and Langmuir equations. The Q/I curve was obtained by plotting QAK (I) versus ΔK (Q), and indicated the presence of low labile K values. The Vertisol samples from the Galante district showed higher availability of K in the solution of these soils. The adsorption isotherms demonstrated that the adsorbed K amounts increased with the concentration of the equilibrium solution. The Langmuir and Freundlich models are well adjusted to soil samples. The soil sample collected in Galante in the "forest" use and management system had a higher maximum adsorption capacity of K. In Queimadas, the retention of potassium in the "crop" was higher than in the "forest". The soil use and management system and the climate influence the maximum potassium adsorption capacity of Vertisol.

Palabras clave : potassium available in soil; Langmuir and Freundlich isotherms; soil management and soil use.

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