Effect of Song Gianh micro-biological organic fertilizer dose on D140 and DT20 soybean varieties in summer-autumn season at Gialam-Hanoi in order to determine the most suitable dose of Song Gianh microbiological organic fertilizer for soybean on Red river non-deposited alluvial soil. The field experiment was carried out by split-plot design with 4 treatments, 3 replications P1: (30 kg N + 90 kg P2O5 + 60 kg K2O)/ha (control)
P2: (30 kg N + 90 kg P2O5 + 60 kg K2O + 0.5 ton Song Gianh micro-biological organic fertilizer)/ha
P3: (30 kg N + 90 kg P2O5 + 60 kg K2O + 1.0 ton Song Gianh micro-biological organic fertilizer)/ha va P4: (30 kg N + 90 kg P2O5 + 60 kg K2O + 1.5 tons Song Gianh micro-biological organic fertilizer)/ha. Research results showed that 1 ton of Song Gianh micro-biological organic fertilizer combined with 30 kg N + 90 kg P2O5 + 60 kg K2O per ha (P3) to apply for D140 and DT20 soybean varieties given high grain yield (D140 and DT20 crop yields of 23.55 - 24.35 and 25.36 - 26.82 quintal/ha, respectively)
and the highest economic effectiveness (D140 and DT20 net proceeds by VND millions 11.081- 11.406 and 13.886 - 15.358 per crop/ha, respectively).