A technique was developed for labeling the leguminous plant tissue with nitrogen (15N) to obtain labelled material for nitrogen dynamic studies. Sunnhemp (Crotalaria juncea L.) and velvet beans (Mucuna aterrima, sinonímia Stizolobium aterrimum Piper & Tracy) were grown in pots containing 10 kg of a Red Yellow Podzolic soil, under greenhouse conditions. The rate of 1.2 g of nitrogen (ammonium sulphate with 11.37 atom % 15N) per pot was applied three times. The labelled dried plant material showed 3.177 and 4.337 of atom % 15N, respectively for velvet beans and sunnhemp.
15N-fertilizer; labelled leguminous plant; green manure
