Growth and Yield Characteristics of Sunflower (Helianthus annuus) Grown with Sewage Sludge and Domestic Sewage Reuse in Dschang – Cameroon

Sewage sludge and sewage from primary treatment of domestic sewage are increasingly being used as alternatives to solve the problems of regressive soil fertility and improve crop yields. Sunflower (Helianthus annuus L.) is an oilseed with high nutritional and economic values. This study aimed at improving the growth and achenes yield of sunflower using sewage sludge and sewage from primary treatment of domestic sewage treatment plant. The treatments used were a negative control T0 (no fertilizer), three doses of granulated sewage sludge: 15 t ha-1 (T1), 30 t ha-1 (T2), 45 t ha-1 (T3), three doses of treated sewage: 300 m3 ha-1 (T4), 450 m3 ha-1 (T5), 600 m3 ha-1 (T6) and a positive control T7 (0.6 t ha-1 of NPK (7-18-30) synthetic fertilizer). Results indicated that the growth and productivity characteristics of plants of the different treatments with sewage, sewage sludge, were statistically higher than those of the negative control, but similar with the positive control. The sewage sludge at the dose of 45 t.ha-1 expressed higher growth characteristics. The best achenes yield characteristics were obtained from the treatment with 30 t.ha-1 of granulated sewage sludge (6.82 t ha-1) seconded with those treated with 15 t ha-1 sludge and 600 m3 ha-1 of treated sewage having achenes yield of 6.73 and 6.33 t ha-1, respectively. The yield values of 15 t ha-1, 30 t ha-1 and 600 m3 ha-1 were statistically higher than that of the positive control (5.76 t ha-1), while the rest were similar with positive control. The evolution of plant productivity was proportional to the quantity of treated sewage used, whereas it was inversely proportional to the quantity of sewage sludge used. This reveals a potential harmful effect at high concentrations of sludge. The results of this study confirm that granulated sewage sludge and treated domestic sewage from primary treatment positively influenced sunflower growth and achenes yield and can be used as alternative ecological fertilizers for the production of sunflower in Dschang – Cameroon. Economically, these two biofertilizers are often discharged as waste and their recovery as fertilizers in agriculture is an added value.