Residual Effect of Organic Fertilisation on Some Agronomic and Physico - Chemical Properties of Three Varieties of Cassava (Manihot esculenta C.)

Cassava (Manihot esculenta C.) is the second food crop produced after yam in C?te d'Ivoire with many products derived widely consumed. Faced with the impoverishment of the soil, organic fertilization is increasingly used by farmers. The study proposes is to assess the residual impact of organic fertilization with cowpea plants (Vigna unguiculata L.) at planting densities of 62, 500; 125, 000 and 250, 000 plants / haand poultry manure at rates 5; 10 and 15 t/ha, on certain agronomic andphysico - chemical properties of varieties of cassavaYavo, BoCou 1 and Yac?. To do this, an experimental plot was installed. After 15 months of cassava cultivation in a first cycle where fertilizers were used, a second cycle of 15 months was conducted instead of the first without adding fertilizers. The parameters of cassava roots studied were determined for the second cycle. The resultsshow that the residual effect of these organics fertilizers increasedtuberized roots yield. These increases go up to 159.58% withpoultry manure. In addition, the residual effect of these fertilizers resulted in abeneficial increase, respectively, in dry matter and ash contents of up to 61.12% and 470.30%.