Dynamics of rubber cultivation in production systems in mountain zone of Côte d’Ivoire

— In Côte d'Ivoire, rubber cultivation is experiencing spectacular development. With land saturation in its traditional growing zones, rubber trees increasingly occupies new regions, including the west of the country. The objective of this study is to assess the place of rubber trees in the dynamics of production systems in the semi-mountainous region of western Côte d'Ivoire. This study was carried out through a survey carried out among nearly 402 rubber planters from the Tonkpi region and part of the Guemon region. A semi-open questionnaire was used to collect data, particularly those relating to the profile of the farmer and the relationships that prevail between rubber trees and other crops. Data analyzes have shown that the total area of production systems is 2758.12 ha, or 6.86 ha per farmer, and that of rubber trees is 1268.69 ha, or 2.41 ha per farmer. The average age of rubber fields is 8 years in 2019. Rubber plots were established between 1990 and 2019, of which 84 pc between 2007 and 2015. Planters use perennial polyculture in 76.87 pc of cases. Rubber cultivation occupies 46 p.c. of cultivated areas with coffee (45.63 p.c.) as the dominant previous crop. The rubber tree is grown in combination in 67.87 p.c. of cultural situations. Food crops are mostly (86.83 p.c.) used in associations. Rubber cultivation occupies half of the production system in western Côte d'Ivoire and the relations which prevail between rubber trees and the other components of this system are, on the one part, relations of substitution of rubber for perennial cultures (Coffee) and on the other part relations of association with food crops.


I. INTRODUCTION
Since the independence of the Côte d'Ivoire in 1960, its agriculture has been dominated by the coffee-cocoa duo. The fluctuation in world prices of these two crops, coffee and cocoa, observed since the 1980s, has imposed on the State of Côte d'Ivoire a policy of diversification of export crops through the introduction of oil palm, coconut tree, cotton tree, cashew tree, sugar cane and rubber tree (Kéli, 2003). This latter speculation, initially developed by the large-scale farming sector, is now mainly carried out by small peasant farms (Ruf, 2009). First (1st) African producer of natural rubber since 1997, Côte d'Ivoire is now 6th in the world, with an estimated area of over 534,000 hectares for a production of 603,000 tons of dry rubber in 2017 (Kouassi, 2018).
Thanks to the improvement in the prices of natural rubber, the Côte d'Ivoire has defined a vast program of intensification and extension of rubber cultivation. This program, in support of smallholders, provided for the creation of 30,000 ha per year, with the objective of reaching a production of 600,000 tonnes of rubber by 2020 (Wahounou et al., 2013). But very quickly, the Côte The objective of this study is to determine the place of rubber trees in the dynamics of production systems in western Côte d'Ivoire.

II. RESEARCH PROCEDURE
The site of study The study was carried out in four (04)

Preliminary investigation
A preliminary survey was carried out with resource persons from research and supervisory structures, in order to constitute a database necessary for sampling rubber farms. This database includes the number of rubber planters, the areas of the plots, and the years of creation of rubber fields in the Tonkpi region.

Sampling
The sample was obtained following a random selection carried out among rubber growers in each department so that it is representative. The formula below, which is the one recommended for calculating the size of a finite population sample, allowed us to determine the sample size for a confidence level s = 95 pc (very often used level), t = 1.96 and the "p" proportion to be estimated is nearly 50 p.c.
• N: Size of parent population • n: Sample size for a parent population • e: Margin of error that we give ourselves for the size that we want to estimate (for example we want to know the real proportion to within 5 p.c.)

Data collect
Data collection consisted of individual interviews with rubber growers and observations made in the fields. The data collected focused on the areas and the installation dynamics of rubber trees.

Data analysis
The data were entered on Excel 2010 software which was also used to determine the averages, frequencies and to produce the graphs. Descriptive statistics and crossover tables were performed on Stata SE 14 software.

III. RESULTS
The surveys focused on 402 rubber farmers, with 526 rubber farms, spread over 49 villages including 13 in the department of Biankouma, 11 in the department of Danané, 2 in Kouibly and 25 in the department of Man.
The villages visited are grouped into 12 different subprefectures.  (Table II). The most important production systems per farmer are those of Danané (8.61 ha) and the weakest are those of Man (6.02 ha).

Place of rubber in production systems
The total area of rubber tree plantations in this production system is 1268.69 ha (Table I) Rubber cultivation thus occupies 46 p.c. of the farmland in the semi-mountainous region of Côte d'Ivoire ( Figure 3). This rubber tree occupancy rate is higher in Man (52.51 p.c.) and lower in Kouibly (23.49 p.c.).

Dynamics of the establishment of rubber plots
The

Crop associations involving rubber
The cultivation systems practiced relate, in 67.87 p.c. of cases, to associated cultures ( Figure 5). The duration of associations with rubber varies from two (02) to ten (10)

Place of rubber in production systems
Surveys show that the orientation towards rubber cultivation does not exclude the presence of other perennial crops, notably coffee, cocoa, oil palm, cashew and cola. The total surface area of the rubber growers surveyed is 2758.12 ha, or 6.86 ha per farmer. This area is greater than that of Akiés planters (Attiés) which is 3.4 ha (Ruf, 2018). Farms with only rubber as an export crop represent 23.13 p.c. of cases. According to Ruf (2018), young planters are more interested in rubber cultivation as they easily overcome six years of unproductivity. This could justify the fact that some growers only engage in rubber cultivation. Also, the first two fields were established in 1990 in Man and Biankouma. These creations were followed by two other plots set up in 1997 in Danané. According to Ruf (2009), the Ivory Coast owes the doubling of its production in 8 years to the village sector whose performance is approaching each year the production threshold of industrial plantations. Thus, the big wave of establishment is between 2007 and 2015 with 84 p.c. of fields created. According to Koulibaly (2016), rubber cultivation has increased dramatically with an increase of 479.38 p.c. in its recorded areas. This would be due to the price of the kilogram of rubber which increased from 2001 to 2010. It went from three hundred and seventy-five (375) FCFA to one thousand (1,000) FCFA. According to Akmel (2018), this state policy aimed to encourage actors, so that they become more involved in rubber production. This is corroborated by the increase in production to 603,000 tonnes in 2017 (Kouassi, 2018). Furthermore, the rationalization of income created by rubber cultivation due to the monthly payment of production could justify the massive investment of young people in rubber. Also, rubber farmers participate in the restoration of the green fabric.

Previous crops of rubber
The previous dominant crop is coffee with a proportion of 45.63 p.c. This shows that rubber trees are in the process of replacing coffee. The substitution of rubber for other export crops has also been revealed by surveys in the Dabou region in Côte d'Ivoire (Akmel, 2016). The phenomenon of substitution of rubber tree plantations for old cocoa or coffee trees is not new (Ruf, 2009

Crop associations involving rubber
The cultivation systems used relate, in 67.87 p.c. of cases, to associated cultures. This rate is lower than that of the Songon sub-prefecture which is 85.43 p.c. of farmers surveyed (Kouamé 2014). Cultural association could allow diversification of production and sources of income. However, according to the farmers surveyed, the cropping association in the semi-mountainous region of Côte d'Ivoire is motivated by the simultaneous maintenance of associated crops (48.61 pc) and the lack of land (44.44 pc). Benefits of this practice of combining annual crops with trees may include food security for households, income generated from the sale of both products, weed control and better use of cultivated resources (Balogoun et al., 2014). According to Kouamé (2014), To fill the land shortage, the populations practice the association of cultures. The duration of associations with rubber varies from two (02) to ten (10) years, depending on speculation. In fact, during the immaturity period of the rubber tree (6 years), producers form associations to ensure food security during this period, create sources of income and implement cultivation techniques likely to help the growth. maintenance of the rubber tree. In addition, intercropping brings organic matter to the soil through the decomposition of crop residues. Monoculture with leguminous cover (often Pueraria) between the rows of rubber trees is a satisfactory practice from an agronomic point of view thanks to the fight against erosion and against weeds, supply of nitrogen and maintenance of humidity (IRRDB, 1996). The Hévéa brasiliensis species is actually cultivated in association with other domesticated species such as cover legumes (Pueraria phaseoloïdes, Centrosema pubescens, etc.), food and industrial species (Obouayeba et al., 2016). The crops set up on the whole of the young plot, accept a valuation of the land while guaranteeing a maintenance of the space beneficial to the development of the young rubber plants. The crops grown depend on the eating habits of the farm manager and his family. These are usually mixtures of species including plantain, corn, macabo, peanut, pistachio, yam and sweet potato. (Thierry, 2005). The rubberwood associations in the semimountainous West have involved eleven (11) speculations, including seven (7) food crops and five (5)

V. CONCLUSION
The objective of the study was to assess the place of rubber trees in the dynamics of production systems in western Côte d'Ivoire. The study showed that 76.87 p.c. of planters are using perennial polyculture. The total surface area of the rubber growers' production systems surveyed is 2758.12 ha with an average of 6.85 ha per farmer and that of rubber trees is 1268.69 ha or 2.41 ha per farmer. Rubber cultivation, which thus occupies 46 pc of sown areas, could be considered as a substitute crop for old crops. The age of the rubber orchard is between 1 and 30 years with an average of 8 years in 2019. The great wave of he establishment is between 2007 and 2015 with 84 pc of field creation. Considering the juvenile age of rubber trees in the west, there could be a bright future.
In perspective, effective associations should be determined for optimal use of agrarian space. This study will overcome the problems of substituting rubber for other crops in the study area with a view to diversified and sustainable agriculture.