Abstract

SANTANA, Gessionei da S.; COELHO, Eugênio F.; SILVA, Tibério S. M. da  and  RAMOS, Márcio M.. Relationship between potassium in the soil solution, soil water content and bulk electrical conductivity. Rev. bras. eng. agríc. ambient. [online]. 2007, vol.11, n.2, pp. 142-151. ISSN 1807-1929.  http://dx.doi.org/10.1590/S1415-43662007000200003.

The objective of this work was to evaluate the feasibility of estimating the potassium (K) concentration in the soil solution, under laboratory conditions, for loamy (CT_f) and sandy loam (CT_fa ) soils, through models that relate soil water content (q), bulk electrical conductivity (CEa) and soil solution electrical conductivity (CEw). Five potassium chloride solutions with electrical conductivities of 1.0, 2.5, 4.0, 5.5 and 7.0 dS m^-1, were applied in a soil packed in PVC columns in order to obtain five soil water contents (17.0 ± 1.4, 19.0 ± 1.8, 21.4 ± 2.2, 23.4 ± 2.2 and 26.0 ± 3.0%, on volume basis). Readings of q and CEa were obtained by using time domain reflectometry (TDR) equipment and soil solution was extracted by a water sampler to determine CEw and K. Three models were fitted to the data by an electronic sheet. It is possible to estimate potassium concentration in the soil solution fromqand CEa under laboratory conditions by the models of Rhoades et al. (1976), Vogeler et al. (1996) and Mualen & Friedman (1991) using a potential relationship between CEw and K in the range of 0 to 60 and 0 to 120 mg L^-1, for soils of CT_f and CT_fa, respectively.

Keywords : ionic concentration; TDR; fertirrigation management.