The determination of mineral nitrogen in soils has been successively done by Conway's diffusion method.Owing to the high content of amraonical nitrogen present in most manures,and also to the turbidity of their extracts,this method fails to give good duplicates in ammonia determination from separated aliquots.The present article gives a modified technique of Conway's procedure for the extraction and determination of ammonical nitrogen in manures with percentage recovery ranging 97.2-104%.5 drams of sample are extracted by a 10% KCl-0.1N HCl solution with sample-extractant ratio from 1:10 to 1:20 or even wider in case of manures with exceedingly high content of ammonical nitrogen.A 2 ml aliquot,containing NH4-N-100γ is used for analysis.The distillation of NH4-N can be completed in 24 hrs by MgO displacement in Conway's dish at room temperature.
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莫淑勛,俞金洲.有机肥料中氨态氮的測定——微量扩散法[J].土壤学报,1962,10(3):305-307. S. H. Mo, T. C. Y. DETERMINATION OF AMMONIA IN ORGANIC MANURES BY THE MICRODIFFUSION METHOD[J]. Acta Pedologica Sinica,1962,10(3):305-307.