DETERMINATION OF THE INORGANIC NITROGEN IN THE CORN PLANT BY THE EXPRESSED SAP METHOD

Abstract

Total inorganic N was determined on the sap or juice at a pressure of 5000 lbs. per sq. in. from various parts of the plant. The Sessions and Shive cold aspiration method after slight modification gave results as good as the Kjel-dahl method applied to hot alcoholic extracts of the green plant material. There was close agreement between successive portions of sap obtained at increasing pressure, indicating that the amount of inorganic N obtained in the sap is proportional to any fraction of the total moisture expressed. Sap samples were satisfactorily preserved by freezing in stoppered bottles for long periods of time. Toluene preservation appears satisfactory for shorter periods. The corn stalk contained 76% and the portion of the stalk below the ear contained 57% of the total inorganic N in the plant, indicating the requirement of careful technique in preparation of the sample for sap expression.