Measurement of electrical conductivity and PH in NPK fertilizer and potassium chloride (kcl) solutions in agricultural soil analysis

The measuring electrical conductivity and soil pH is essential in determining the optimal amounts of fertilizer to be applied to a soil so as not to affect its structure and fertility, since excessive application of fertilizers is counterproductive to soil quality. Therefore, the research being developed to address this issue applies a methodology through the preparation of calibration solutions that allow the study and analysis of the behavior of NPK fertilizer (Nitrogen, Phosphorus and Potassium) in the soil. This fertilizer is widely used in Colombian agriculture, which is affected by variables such as temperature.

Through the development of this project, a replicable methodology was generated for the measurement of electrical conductivity and pH. This is achieved by initially preparing aqueous solutions of potassium chloride according to the NTC 5596 standard, through which an increase in electrical conductivity is observed with the increase of this compound. In a second phase, solutions with NPK fertilizer (Nitrogen, phosphorus and potassium) were prepared in different concentrations (from 4 to 20 mg/mL, in increments of 1 mg/mL), and each sample was subjected to temperature variations (from less than 10 °C to 40 °C) to analyze its effect on the measurements.

Preliminary results show that electrical conductivity increases with the amount of NPK, while pH remains relatively constant with the change of fertilizer and only shows a slight decrease with increasing temperature. On the other hand, electrical conductivity decreases significantly with increasing temperature.

Preliminary, it is concluded in the progress of the project that one of the key aspects is the methodological standardization in the preparation of the solutions to be measured, since an adequate measurement of electrical conductivity and pH required to predictively determine the characteristics of the fertilizers to be applied in agricultural soil depends on this.