The study of organic manure should not only be limited to the analysis of its effects on crop development and yield, but should also extend to the examination of its impact on maintaining or increasing soil fertility. A trial was conducted in Ngandajika on the residual effects or nutrient dynamics of two organic materials, cow dung and Tithonia diversifolia. At the end of this trial, the following results were recorded, the T2 treatment or the dung nutrient dynamics gave the yield of 2.87 T/ha and 3.16 T/ha respectively in maize monoculture and in maize-cowpea association, which are significantly higher than that achieved with T1 or Tithonia diversifolia nutrient dynamics 2.27 T/ha and 2.55 T/ha and the latter more than the control (1.41 T/ha and 1.63 T/ha). Thus, we can therefore remember that the nutrient dynamics of cow dung are stronger than those of Tithonia diversifolia on the maize crop more than on the control. Both organic manures with their element dynamics not only increase the yield of maize cultivation, they also increase soil fertility.

The objective of this trial was to evaluate the impact of the combination of manure (cow dung + DAP) and (Tithonia + DAP) on the growth and yield of the maize crop in monoculture and in association with cowpea compared to that of DAP + Urea. To assess this impact (the effects), measurements were made on the crop’s growth parameters including emergence rate, crown diameter, plant height and number of leaves. As far as production is concerned, measurements were made on the following parameters: the number of ears per plant, the number of rows per ear, the number of grains per row, the weight of a thousand grains and the yield. At the end of this study, the following results were recorded. Compared to the two cropping systems, there is no significant difference between maize monoculture and maize-cowpea combination. As for production parameters, the monoculture has a yield of 2.30 T/ha higher than the maize-cowpea combination with 1.39 T In terms of manure, it is the Tithonia + DAP combination that gives a higher yield than all the other monoculture treatments, while in the maize-cowpea combination, all the treatments show the same higher yield than the control.