University of Arkansas, Fayetteville Division of Agriculture


Microdialysis, Rhizosphere, Nitrogen, Phytoremediation, Flux, Soil Nutrients


Microdialysis, a diffusion-based sampling technique commonly used in biomedical research, has recently been recognized as a candidate for monitoring chemical changes in the rhizosphere. The information it provides about nutrient diffusion may improve nitrogen use efficiency, leading to enhanced management and success of restoration projects. The objective of this study was to determine the efficacy of microdialysis sampling to quantify the relative recoveries (RR%) of nitrate-N and ammonium-N, the two inorganic nitrogen compounds typically found in soil. The effects of microdialysis flow rate, sample medium concentration, and the presence of both analytes in solution on the relative recoveries obtained from dialysate samples were investigated. In comparison to 3.75 and 5.0 μL/min, a flow rate of 2.0 μL/min resulted in an increased relative recovery for both nitrate-N and ammonium-N solutions, at 42.7% and 51.0%, respectively, and was determined to be an optimum rate for subsequent experiments using CMA 20 microdialysis probes. The RR% for both nitrate-N and ammonium-N did not display a statistically significant dependence on the concentration of analyte present in the sample medium. The analytes also did not exhibit interferences, and the presence of both nitrate-N and ammonium-N in the same solution did not influence the RR% of either analyte. The results obtained from this study will assist in validating a novel approach to measuring in situ nitrogen availability in soil with minimal disturbance.