Effects of year season (SEAS), organic fertilization (N) and harvest frequency (FREQ) on forage yield and composition were evaluated in a high density mulberry forage bank, established under low input tropical farming conditions. The experiment, replicated 2 consecutive years, was arranged in 18 treatments resulting from a 3 × 3 × 2 factorial design combining 3 FREQ (60, 90 and 120 d), 3 N rates (100, 300 and 500 kg N/ha/year) and the 2 seasons (RAIN and DRY). Forage yield, leaf to stem ratio, the edible fraction (EDIB, %), nutrient content by plant fraction (PFR; i.e., leaves, tender and ligneous stems) and the maturity indexes were monitored. Either forage yield or nutrient content was strongly affected by SEAS, FREQ, PFR, N rate and, in some cases, by their interactions. Total forage yield increased (P < 0.0001) with FREQ (26.5, 31.2 and 40.6 t for 60, 90 and 120 d, respectively), irrespective of the SEAS (44.7 and 21.1 t for RAIN and DRY, respectively), PFR (19.2, 3.0 and 10.7 t for LEAF, TST and LST, respectively) or N (28.1, 32.0 and 38.5 t for 100, 300 and 500 kg N/ha/year, respectively). The EDIB yield was higher in RAIN (25.3 vs. 13.2 t; RAIN vs. DRY) and diminished while increasing FREQ, irrespective of SEAS or N. This decrease in EDIB yield was directly related to the decrease in the LEAF proportion and the concomitant increase of the LST fraction with FREQ. Harvesting at 60 and 90 d in RAIN and DRY, respectively, with a N rate of 300 kg N/ha/year seems the best agronomic choice as a most optimal condition between forage yield and nutritive value.