Effet fertilisant et phytosanitaire du compost des dechets ménagers et de la fumure à base des parches de café dans l’amélioration de la culture du maïs (Zea mays L.) en zone forestière du Cameroun

Abstract

Maize is widely cultivated and consumed in Cameroon, its cultivation requires a high fertilizer supply. However, existing inorganic fertilizers on the market are often not affordable, especially for small farmers, which results in lower maize yields in the country. On the other hand, Cameroonian cities are languishing in solid waste with an abundance of biodegradable organic waste which, once transformed into compost, can be used to increase the yield of corn. This study evaluated the fertilizing and phytosanitary effect of manure based on compost from household waste and coffee grounds in the cultivation of the three varieties of corn. An experiment was conducted in the Megana sites for two years (2014 and 2015), followed by a verification test of the results obtained in Megana with a view to their generalization in the Nkolfon site for two years also (2016 and 2017) . Each experiment was carried out according to a factorial “split-plot” factor randomized to 4 blocks with in the main plot the varieties (V1: local variety, V2: improved variety CMS 8501, V3: improved variety CMS 8704) and in sub-plot the treatments fertilizers (T0: unfertilized control, T1: manure based on coffee grounds, T2: household waste compost, T3: NPK mineral fertilizer (20-10- 10). There is a positive linear correlation between the treatments with a coefficient positive correlation which shows that the absence of addition of a basic fertilizer does not have an impact on the different treatments. The diameter at the collar, the number of leaves, the leaf area, and the height of the plant, the ears and grain yield were used to assess the performance of different fertilizer treatments. The incidence and severity of fungal diseases were used for the phytosanitary aspect. Economic evaluation of the four treatments was also carried out to determine the economic viability of applying these fertilizers to the corn. The effect of the types of manure on the growth parameters showed that T1, T2, and T3 presented diameters at the collar, the number of leaves, the leaf area and the height of the plant significantly different compared to T0 in the Megana site during the two years of experimentation (2014 and 2015). Also, the varietal effect shows that V1 presented the diameter at the collar higher and a larger size than V2 and V3.The effect of the treatments on grain yield shows that T0 was the least productive than T1, T2, and T3. In 2014 and 2015 in Megana, the grain yield was lower at T0 (1.5 ± 0.7 t.ha-1 in 2014 and 0.9 ± 0.7 t.ha-1in 2015) than in T3 (3.6 ± 2 t.ha-1 in 2014 and 3.9 ± 2 t.ha-1 in 2015) which is statistically similar to T2 (3.4 ± 2 t.ha-1 in 2014 and 3.8 ± 2 t.ha-1 in 2015). T1 presented the intermediate rate (2.1 ± 1.1 t.ha-1 in 2014 and 1.9 ± 2.1 t.ha-1 2015). In the Megana site, the effect of fertilizer treatments on coal cob, Fusarium head blight and helminthosporiasis showed significant differences in the incidence and severity of the diseases. For example, with regard to coal cob, only T1 and T2 have been attacked by the disease. Regarding Fusarium head blight and helminthosporiasis, T0 had the highest incidence and severity rates compared to the three fertilizer treatments, and T2 had the lowest rates. The phytosanitary effect of the types of manure on parasitic diseases of fungal origin has revealed that compost has phytosanitary virtues capable of reducing the attack and the spread of Helminthosporim turcicum detected in fields. On the other hand, treatments based on coffee grounds and NPK mineral fertilizer (20-10-10) have an ephemeral effect on these diseases. The positive effect of compost would result in the presence within it of active microorganisms which would act either by entering into competition (living space, water, nutrients) with the pathogenic agent, or by secreting harmful substances (toxins) for their survival which would have contributed to decrease the activity of the pathogen.The in vitro study showed that the aqueous extract (sterilized or unsterilized) of the compost inhibited the radial growth of Helminthosporim turcicum and significantly delayed its development in culture medium. This aqueous compost extract is said to contain microorganisms responsible for the production of suppressants capable of inhibiting the mycelial growth mechanisms of Helminthosporium turcicum.In view of the results obtained, household waste compost is the most economically viable treatment due to the low operating costs and higher returns on investment and, therefore, it can be recommended to farmers as bio-fertilization with virtues phytosanitary capable of increasing the yield of corn with the assurance of economic profitability.