Stems of barley and wheat plants of wide range innutritional status were analysed for sap ΝΟ 3 concentration at the tillering stage using both "Merckoquant" nitrate test strips and a specific-ion nitrate electrode. Even though the "Merckoquanf'test strips used in this study did not give precise NO 3 readings they were found to be a satisfactory method for determining the NO 3 content of stems of cereals, and can be used in situ by farmers to predict the necessity of Ν fertilization for maximum grain yield.If the NO 3 sensitive area on the test strip is coloured to match the standard 500 ppm NO 3 colour in less than 30 seconds, after the application of sap, this is an indication of adequate Ν nutrition. If the 500 ppm NO 3 colour standard is reached between 30 to 60 seconds, then this is an indication of intermediate Ν nutrition and fertilization is recommended only under favorable weather conditions. If colour development of the test strip for the 500 ppm N0 3 standard takes more than 60 seconds, or the colour developed does not reach this standard, this