Application Effects of Legumes On Growth, Yield of Vegetables and Nitrogen Dynamics by Using 15N Tracer.

Pot experiments were performed with 2 kinds of vegetables, komatsuna (Brassica rapa var. perviridis) and radish (Raphanus sativus var. sativus). The pot soil was amended with fresh hairy vetch (HV, 19.0 gN/m²), white clover (WC, 17.6 gN/m²) or chemical fertilizer (CF, 20.0 gN/m²) labeled with ¹⁵N tracer as a basal fertilizer, mixed with the soil thoroughly and set for 2 weeks before seeding.

No inhibition on the germination of the vegetables was observed in the all treatments. In HV and WC, initial growth of both of the vegetables was higher than that in CF. Fresh weight of komatsuna in HV was significantly  (P < 0.05) higher than that in WC and CF. However fresh weight of radish root (5.52 g plant^-1) was significantly (P < 0.05) higher than that of HV (3.57 g plant^-1) and WC (2.49 g plant^-1). Komatsuna and radish seemed to have different characteristics on preferable N sources.

Nitrogen recovery of komatsuna was higher in HV (60.1% of applied N) than that in WC (36.4%) and CF (32.5%). On the other hand, that of radish was lower, 32.9% in HV, 25.1% in CF and 21.4% in WC. It may be due to a shorter cultivation period than komatsuna. These results show that HV and WC are useful organic materials as basal fertilizer for the vegetables.