Development of a Biomimetic Root Oxygen Bioavailability Sensor

Abstract

Low oxygen availability in soil can impair root function, thereby decreasing agronomic productivity. Without oxygen to support mitochondrial respiration, energy levels in roots may limit mineral nutrient (N, P, K) transport. Traditional methods for measuring soil oxygenation include the use of redox electrodes and polarographic oxygen sensors. These approaches are limited to measuring oxygen concentrations at specific locations and cannot determine the bio-availability of that oxygen to a growing root. An innovative approach has been developed for direct measurement of oxygen bioavailability. Instead of building the sensor to measure oxygen concentrations, it is possible to construct an electrochemical system in a manner that makes it sensitive to changes in oxygen transport and availability in the soil. Furthermore, it is even possible to construct the sensor to match the oxygen consumption characteristics of a specific root tip, which is important because most metabolism and nutrient uptake occurs here. This is accomplished by using a conductive-gel membrane system that allows sensor profiles to be engineered to match the metabolic profiles of specific species. If constructed to these standards, the sensor will biomimetically replicate biophysical oxygen depletion profiles that are analogous to those found in the rhizosphere of a growing root tip. The biomimetic root oxygen bio-availability (ROB) sensor integrates all biotic and abiotic factors in the soil that limit oxygen transport to the root, while providing real-time sensing. This new sensor technology could be used as a research tool or as a closed-loop control system for field and greenhouse irrigation.