Study on a Method for Determining Fertilizer Type and Concentration Based on Fertilizer Dielectric Constant and Electrical Conductivity

The rapid detection of fertilizer solutions plays a crucial role in automated mixing or precise variable-rate fertilization. This paper proposes a method for detecting the type and concentration of single-element fertilizers. The experiment focuses on three types of single-element fertilizers: urea, calcium superphosphate, and potassium sulfate. For each type of fertilizer solution, 20 test samples are prepared within a concentration range of 0.1% to 2%, with increments of 0.1%. The dielectric constant (ε) and electrical conductivity (σ) of the fertilizer solutions are measured using a liquid composite dielectric constant measurement system. The experimental results indicate that the maximum relative error in the stability test of single-element fertilizer solutions is 0.32%, while the maximum relative error in concentration testing is 6.25%. The method proposed in this paper enables the rapid and accurate identification of different types of single-element fertilizer solutions and their concentrations, effectively minimizing errors during the fertilization process and holding significant implications for achieving fully automated irrigation fertilization.