Côte d’Ivoire is the leading coconut plantation in Africa [1] , with several industrial plantations and numerous small private farms, mainly located on the tertiary to quaternary sands along the coast, on which more than 20,000 families depend [2] . Coconut plays a key role in people’s lives in terms of social and economic uses [3] .

However, the majority of this coconut field is planted with the local variety, Grand Ouest Africain (GOA), which has a low yield and low density (143 trees/ha) [4] . In addition to the biotic difficulties (pests, diseases), this coconut plantation is under ever-increasing land pressure, which is considerably reducing the area available for cultivation. This situation is leading to a drop in yields and, consequently, in people’s incomes [3] . To remedy the situation, research is proposing to renew the coconut plantations with improved, resistant varieties at high planting densities, and to grow alternative crops such as plantain in the coconut inter-rows.

Indeed, sold on the market, plantain contributes to the GDP of countries in Central and West Africa, helps to diversify people’s incomes and thus helps to reduce poverty [5] . Plantain is one of the main sources of carbohydrates [6] and feeds many people around the world, particularly in tropical countries [7] . In Côte d’Ivoire, plantain is the third most important food crop, after yam and cassava, with average annual production estimated at around 1.7 million tonnes [8] . However, plantain is one of the staple foods of the Ivorian population [9] , and despite its socio-economic importance, large-scale plantain cultivation is confined to the East, Centre-West and West zones, where soil conditions are favourable [10] . As a result, this commodity is often irregular on local markets.

In the coastal zone, plantain cultivation techniques remain rudimentary, using very few inputs. In addition, farmers who grow plantain mainly use the Corne 1 variety, which has limited intrinsic capacity [11] . This variety has poor resistance to disease and is mainly grown in areas where there is a lot of humidity at all times, such as low-lying areas, rubbish dumps and around houses [11] .

It is therefore necessary to test other, better-performing varieties in order to meet the ever-increasing market demand for plantain. The aim of this study is therefore to find an ideal technical itinerary for growing and intercropping the high-yielding PITA 3 plantain, popularised by the CNRA under coconut base, on the tertiary sands of Côte d’Ivoire.

The study was carried out at the Marc DELORME research station, on the coast in south-eastern Côte d’Ivoire. The station is located on littoral, in Abidjan district southern Côte d’Ivoire, between 3˚82' - 3˚87' West longitude and 5˚26' - 5˚29' North latitude (Figure 1).

The soil pH is acid, around 5, in depths 0 - 20 and 20 - 40 cm. it is consists

mainly of fine sand (over 80%) with very little silt and clay (less than 10% each).

The soil composition in chemical of elements and exchangeable bases at the beginning of the trial, analysed at the Laboratory of the National Soil Bureau of Burkina Faso (BUNASOLS), are shown in Table 1.

The climate is characterized by four seasons: two dry seasons and two rainy

1 ppm = 1 mg/kg, O.M.: Organic matter, CEC: Exchangeable bases.

seasons. For the dry seasons, the longest covers the months of December to March and the shortest goes from August to September. For the rainy seasons, the longest covers April to July and the shortest goes from October to November. Over the decade from 2012 to 2021, average monthly rainfall ranged from 33.4 mm (January) to 464.1 mm (June) and temperatures from 25.3˚C (September) to 28.3˚C (April) (Figure 2). The sunshine was around 2000 hours a year⁻¹ and relative humidity fluctuated between 80% and 90%.

Fertilised PITA 3 plantains showed better agromorphological performance than unfertilised ones (D6). This lack of improvement in the performance of unfertilised plants indicates the positive effect of fertilisers on plantain [12] , and the usefulness of fertilisers in sandy soil cultivation [13] . The number of leaves, height and circumference of D3 plants (9 kg of chicken droppings per banana plant) were highest at the tenth month with values of 12 cm; 264.08 cm and 57.68 cm respectively. These performances were immediately followed by those of the D1 banana plants (6 kg of droppings per plant). Chicken droppings are therefore an essential mineral reserve for plantain growth and ripening. According to [14] , the application of hen droppings provides additional quantities of nitrogen, phosphorus, potassium and magnesium to the pool of mineral elements in the soil, thereby increasing the nutrient content [15] . The plants would integrate the mineral elements supplied, in particular nitrogen, into their metabolism more efficiently and more slowly. For D3 plantains, the quantity of nitrogen required for development would be better conserved, unlike that available

for D1, D2, D5 and D4 plantains. This is despite the high infiltration capacity of sandy soils. According to [16] , organic matter contributes to the fixation of mineral elements and limits soil leaching. In this sense, leaching and the low nitrogen content of the soil, as indicated by [17] , would be overcome.

For the reference chemical treatment (D4), the height, circumference and number of living leaves at the tenth month of cultivation were statistically lower than for the plants in D1, D5 and particularly D3. The weakness of these parameters could be linked to three factors:

- firstly, the low presence of litter or organic matter [18] . The low natural content of organic matter and clay in the first 20 to 30 centimetres of sandy soils reduces the formation of colloidal matter and clay-humus complex. As a result, cation exchange is reduced, leading to low soil fertility (Koull and Halilat, 2016) [16] ;

- then to the rapid lateral and deep infiltration of rainwater and irrigation water, which leaches out the mineral elements. According to [17] , farmers cultivating sandy soils in Côte d’Ivoire use organic matter as a fertiliser and soil improver to counter the leaching phenomenon;

- lastly, the high heat stored by sandy soils during the day (rapid heating), which would cause mineral fertilisers to react more quickly, particularly urea, which is highly susceptible to evaporation under the effect of heat. This rapid warming of the soil [17] would also reduce the humidity around the plantain. This reduction in humidity would be more pronounced for unfertilised plants and those that have received chemical fertiliser. This would be a major limitation to root development.

Irrigation was therefore very important in maintaining humidity around the plantain. It was an essential condition for their development. The addition of organic fertiliser also improved soil structure and reduced water infiltration deep into the soil. The combination of organic matter and water promotes good humidity, adequate biological activity and better availability of mineral elements [19] , for the plantains needs. This result corroborates those of [20] , during his work on tomatoes in tertiary sandy soils. According to this author, this condition is essential for good vegetative growth and higher yields. However, the absence of fertiliser in D6 plants resulted in stunted growth and death.

The plantains in treatment D3 got interval Planting-Flowering (IPF) and Planting-Cutting (IPC) of 264 and 347 days respectively. These plantains flowered and were harvested 14 and 16 days before those of D1. This difference in cycle would be due to the cumulative effect of the height, circumference and number of leaves of the banana plants [12] , which were greater for the plantain of D3 than for the others. The plantain in D3, reached the flowering and fruiting stage more quickly. In the case of D4 plantain, the high leaching capacity of tertiary sandy soils led to a reduction in the mineral elements required by the plantain, which would have delayed its production cycle. The average weight of plantains bunches receiving fertiliser varied from 5.05 kg to 9.32 kg. Unfertilized plantain did not produce any bunch. In fact, the ability of plantains to produce bunches is strongly linked to the treatment applied and to good vegetative development (Géraldine, 2012) [21] . This would explain the good performance observed in D3, D1 and D5 banana plants, both in terms of parameters relating to vegetative growth (height, girth, number of living leaves) and those relating to production (short cycle, greater mass of bunches).

The study was carried out in order to highlight the effects of two types of fertilization on plantain associated with coconut. It was found that plantain of the PITA 3 variety fertilised with hen droppings performed better agromorphologically than those fertilised with chemical fertiliser and those not fertilised. Banana plants of D3 (9 kg of droppings), D1 (6 kg of droppings), D2 (3 kg of droppings) and D5 (mixture of droppings and chemical fertiliser) all achieved production. However, D3 gave the best values in terms of agromorphological parameters (height, circumference, number of leaves and production). In addition, a shorter production cycle was observed in these banana plants (D3) compared with the other treatments (D1, D2, D4 and D5).

The authors declare no conflicts of interest regarding the publication of this paper.

Coffi, P.-M.J., Ama, J.T., Lekadou, T.T., Traore, S., Agoh, C.F. and Yao, D.M.S. (2023) Evaluation of the Productivity of Intercropping Plantain Cultivar (PITA 3) Fertilized with Two Types of Manure, under Coconut Tree Based (Cocos nucifera L.), on the Tertiary Sands of Côte d’Ivoire. Agricultural Sciences, 14, 1405-1419. https://doi.org/10.4236/as.2023.1410092