NITROGEN TRANSFER FROM NODULATING SOYBEAN (GLYCINE-MAX (L) MERR) TO CORN (ZEA-MAYS L) AND NONNODULATING SOYBEAN IN INTERCROPS - DIRECT N-15 LABELING METHODS

In order to test for N transfer to corn (Zea mays L.) or to non-nodulating soybean (Glycine max [L.] Merr.), nitrogen enriched in N-15 was directly applied to a petiole or to secondary roots of adjacent nodulating soybean. In the field in 1988, N-15 applied directly to a petiole of nodulating soybean was detected at significantly higher levels in adjacent corn plants than when unenriched N was similarly applied. Applications of enriched N and unenriched N to nodulating soybean roots did not result in significant differences in % N-15 an adjacent corn plants. However, in greenhouse experiments, enriched N applied in split-root systems to secondary roots of nodulating soybean, was detected at higher levels in associated corn and non-nodulating soybean than when unenriched N was similarly applied.