A Quantitative Analysis of Nutrient Loss in Surface Runoff Using a Novel Molecularly-Imprinted-Polymer-Based Electrochemical Sensor

Surface runoff poses a significant threat to crop production and the environment. However, most studies on soil properties have not quantified soil nutrient loss as a consequence of soil erosion. This study measures the magnitude of nutrient loss through the development of a novel electrochemical sensor designed for direct and selective detection of nitrates and phosphates in soil runoff. The sensor fabrication process utilizes molecularly imprinted polymer techniques which involve the electrodeposition of polypyrrole with the analyte onto a carbon electrode. Cyclic voltammetry (CV) analysis was performed to evaluate the sensor performance in quantifying nitrates and phosphates across three distinct sets of soil samples collected for analysis. The sensor response was linear to the nitrate concentration in the range of 0.01 M to 100 μM (R2 = 0.9906). The phosphate MIP sensor also displayed a linear response for concentrations ranging from 10 µM to 200 µM (R2 = 0.9901). The sensor exhibited high sensitivity towards nitrates and phosphates and effectively detected nutrient levels in the soil solution with a detection limit of 25 μM and 53 μM, respectively. The sensor was then evaluated for degradation and repeatability, which produced a relative standard deviation of 13.5% and 8.2% for nitrate and phosphate, respectively. Further, the loss of nutrients in different soil types indicated the need for soil characterization before the application of fertilizer to reduce the nutrient loss in the event of surface runoff.