Current fertiliser recommendations for nitrogen are limited in their accuracy and may be improved by the use of simple on-farm soil rapid tests. This paper investigates the potential for using nitrate (NO 3 ？) ion selective electrodes (ISEs) and dual wavelength UV spectroscopy as part of a rapid soil NO 3 ？ diagnostic test. Three soil types, representing the major soil types for agriculture in the western UK, were tested. For the three soils, the ISE rapid test procedure gave a near 1:1 response ( r 2 = 0.978, 0.968, 0.989) compared to the internationally-approved standard laboratory method. However, the accuracy of the ISE rapid test was reduced at low soil NO 3 ？ concentrations (<10 mg NO 3 ？ L ？1). We also show that NO 3 ？ analysis of H 2O soil extracts by dual wavelength UV spectroscopy was also highly correlated ( r 2 = 0.978, 0.983, 0.991) to the standard laboratory method. We conclude that both ISE and dual wavelength UV spectroscopy have clear potential to be used for the rapid on-farm determination of soil NO 3 ？ concentration. Barriers to use of these field-based assessment tools include, farmer perception of cost-benefit, general attitude to new technologies and the ability to generate useful fertiliser use strategies from soil NO 3 ？ measurements.
Iversen, T.; Grant, R.; Nielsen, K. Nitrogen enrichment of European inland and marine waters with special attention to Danish policy measures. Environ. Pollut. 1998, 102, 771–780, doi:10.1016/S0269-7491(98)80111-5.
Jemison, J.M.; Fox, R.H. A quick-test procedure for soil and plant-tissue nitrates using test strips and a hand-held reflectometer. Commun. Soil Sci. Plant Anal. 1988, 19, 1569–1582, doi:10.1080/00103628809368035.
Edwards, A.C.; Hooda, P.S.; Cook, Y. Determination of nitrate in water containing dissolved organic carbon by ultraviolet spectroscopy. Int. J. Environ. Anal. Chem. 2001, 80, 49–59, doi:10.1080/03067310108044385.