Point-of-use soil nitrogen sensor
Measurement of soil nitrogen is important for optimizing use of nitrogen fertilization and variable-rate fertilization, but is not performed regularly. Rather, farmers often rely on advice from governments, suppliers and peers when deciding the economically optimal amount of fertilizer to use for crop yields. Ensuing overuse of nitrogen fertilizer has negative environmental impacts, including chemically degraded arable land, eutrophication of surface water and apparent shifts in the make-up of microbial communities in soil. An electrical point-of-use sensor to determine soil NH4 + with a large dynamic range, costing less than US$0.10 per module, has been developed. Using data on soil dynamics from soil pot experiments conducted under eight sets of environmental conditions, a machine learning model was developed to predict the level of NO3 – in soil instantaneously, and future levels of both NH4 + and NO3 –. This work has the potential to inform growers of immediate soil nutrient needs and facilitate, with greater precision, future fertilization plans.
See Grell et al.