Abstract
A pot experiment was performed in a greenhouse in 2003 and 2004 years about the effect of the applied position of the bamboo powder (B) and the nitrogen fertilizer (N) on yield and N, P, K accumulation of soybean cv. Fukuyutaka. Experimental plots were control, B/N-surface, N/B-surface, B-mixed/N-mixed and B-surface/N-mixed plot with three replicates. The difference of each plot was to change the applied position of B and N. Plastic pots with drain (1/5000 a) were filled with Futsukaichi soil. In 2004 years, an effect of applied position of bamboo powder on the utility of applied nitrogen by soybean was investigated by using ammonium sulfate labeled with ^<15>N (20.7 atom%). High SPAD value and N content in leaf was maintained in N/B-surface and B-surface/N-mixed plot in the filling period, and the seed number and yield increased compared to control. On the other hand, the decline of SPAD value at vegetative stage and the seed number in B-mixed/N-mixed plot suggested the large immobilization of applied nitrogen by the mixing of bamboo powder in soil. Therefore, the decrease of seed yield was thought to be the temporary shortage of nitrogen before flowering. Nitrogen absorption from N-fertilizer was depressed by the incorporation of bamboo powder in the ^<15>N experiment. Also, accumulation of K was promoted by application of bamboo powder except of B-mixed/N-mixed plot. Therefore, bamboo powder might be useful for K-fertilizer. From these results, the mulch of bamboo powder increased the seed yield more than the mixed application. And, the mixed application of bamboo powder decreased the seed yield less than no application, this was though that the initial growth of mixed application was depress and the growth rate after flowering stage was recovered equally to that for surface application after flowering, however it didn't reflect on the actual seed production.
