Response from Glycine max (L.) Merrill)

The soil used for our investigations is an extremely acidic ferralsol to which we applied organic matter based on Tithonia diversifolia proposed as a possible solution for restoring the fertility of this type of soil. The general aim was to evaluate its impact on soybean crops sown in pots on two soils from 0-20 cm and 20-40 cm in a bifactorial experimental set-up. Three doses equivalent to 0 kg (D0) 3 kg (D1) and 6 kg MO.m-2 (D2) were tested. The 3 kg MO.m-2 treatment was the best in all cases particularly in terms of yield which was equivalent to 3.72 Mg.ha-1 on the surface soil and 3.48 Mg.ha-1 on the deep soil. The 0 kg MO.m-2 treatment which had borne only a few nodules (8) had only given a yield of 0.486 Mg.ha-1. Proof of Rhizobium inactivity in this type of soil. With the 6 kg MO.m-2 dose a drop in yield was observed (1.642 Mg.ha-1 on average) probably due to excess nitrogen. Nevertheless the results obtained were comparable for the two soil levels studied (0-20cm and 20-40cm).