Measurement results of cob length presented in Table 2 shows that the longest cob is 20.27 cm obtained in the treatment of fertilization of 135 kg N ha-1 + 66kg P2O5 ha-1 without the application of green manure (BOP2), but it is not significantly different from the length of the cob obtained in the application of green manure treatment with the same dose which produces the cob length of 18.30 cm, while the shortest cobs found in the interaction between no fertilizer of N and P with or without green manure (B0P0). In the cob diameter, it is parameter indicated in that the interaction between the application of green manure of crotalaria by fertilizing 135 kg N ha-1 + 66 kg P2O5 ha-1(B1P2) the largest cob diameter obtained is 4.44 cm and significantly different from other interactions, except with the interaction between without green manure with the same dose of fertilizer that is 135 kg N ha-1 + 66kg P2O5 ha-1
(B0P2).