Nature and Extent of Air Pollution and Climate Change Related Stresses on Cocoyam Production in Nigeria

Abstract

There has been a dramatic decline in cocoyam production in Nigeria in recent years due to climate related stressors. We investigated the nature and extent of these impacts and the resilience building strategies used by cocoyam farmers in Nigeria. Data were collected from the farmers in 2010 and 2017 and from FAO statistical database. Results show a yield decline from 8mt/ha in 2005 to 4mt/ha in 2016, due to acid rain, causing bleaching of cocoyam leaves, die back, smaller tubers, early decay of the tubers and decline in the quality and taste of the tubers. Kinds of climate change impact include unusual early rains followed by weeks of dryness, delay onset of rain, long period of dry season, higher temperature, drought and high rate of disease incidence. Resilient building strategies adopted by the farmers were planting deeper or shallower, processing tubers, intensive manure application, multiple cropping and mixed farming.

1. Introduction

Cocoyam refers to two members of the Araceae family (Colocasia esculentum (L.) Schott) and Xanthosoma sagittifolium (L.) Schott) which are staple foods for many people in developing countries in Africa, Asia and the Pacific and the other parts of tropical regions of the world [1, 2]. It is mainly grown for its starchy corms although the leaves are also consumed as vegetables or medicine [3]. They are stem tubers that are widely used for human food, providing food for over 400 million people around the world [4]. Cocoyam has been reported to be the third most important staple root/tuber crop after yam and cassava in Nigeria, second to cassava in Cameroon and first in Ghana [5, 6]. In terms of volume of production, the global production in 2019 stood at 10.54 million tonnes; Nigeria is the largest producer of cocoyam globally, accounting for about 27.14% of the total production with Cameroun, China and Ghana ranked second, third, and fourth [7, 8]. FAO statistical data [7] show that total output of cocoyam in Nigeria for 2019 is close to about 2.86 million tonnes and yield of about 2.88tons/ha, thus underscoring the potential of the crop in meeting the Nigeria food security gap. Cocoyam is commonly grown among small scale farmers who operate within the subsistence economy in most parts of West and Central Africa [1, 9]. It is a widely cultivated crop in both western and eastern region of Nigeria in terms of the area devoted to it and the number of farmers growing it. Indeed, it is a food security crop as almost every household in these regions grows the crop.

In terms of its agronomy, cocoyam thrives well in warm temperatures above 21°C and low temperatures not less than 10°C. It has high moisture requirement and adapts to tropical regions with adequate rainfall distribution. In many countries, cocoyam is often planted under permanent plantations like banana, coconut, citrus, oil palm, cocoa and other agroforestry systems in order to meet the temperature and rainfall requirements [10]. Cocoyam thrives better on a well-drained sandy loamy soil. It produces optimally when planted in fertile soil with a good water retention capacity. Compared to grains, cocoyam is more tolerant in low soil fertility and more resistant to drought, pests and diseases and its roots are storable in the ground for months after they mature [11]. In the traditional farming system where labour is a very limiting factor, cocoyam has endeared itself in the heart of farmers, This is because, in comparison with other root crops cocoyam require the least amount of labour input, thrive better in marginal soils, is shade tolorant and therefore most preffered for interplanting with trees. Thus, has become part of the traditional agroforestry system.

In spite of the many potentials and advantages of cocoyam production, less attention is paid to it when compared to cassava and yam as root crops. Skott et al. [12] and Talwana et al. [13] have identified that research on cocoyam has trailed behind that of other staples in Nigeria and has not received enough deliberate attention to address its research and development in all regional agricultural research centres and therefore, its contribution to food security and economy is underestimated. Authors such as Bello et al. [14], Eboh et al. [15] and Enibe et al. [16] have written on impact of climate change on agriculture, barriers to climate change adaptation in Nigeria, and cocoyam marketing. However, there is paucity of information on the nature and extent of climate change impact on cocoyam production. Chemura et al. [10] assessed the impacts and adaptation strategies to climate change in Zimbabwe. This study will be among the earliest attempts to investigate climate change impact on cocoyam production in Nigeria. The need for such information has become very important due to recent development in cocoyam productions; there is a dramatic declining trend in cocoyam production as well as a shortage of its supply in domestic markets as in recent years [7].

While this decline can be attributed to several causes such as poor cultural practices, inability to adopt new technologies or even pest and diseases; the nature of changes noticed by the farmers as will be discussed below tends to rule out some of the afore-mentioned causes of decline in productivity and suggests stresses occasioned by air pollution and climate change. This is because; cocoyam production is predominantly confined to the forest zones due to its high moisture requirements for optimum yield [17]. According to Taylor et al. [18] the agro-ecological range of cocoyam will be altered under climate change because the crop thrives best under wet, humid environments with little or no ability to adapt to drought. This assertion was collaborated by a modelling study by Kodis et al. [19] who concluded that the potential for cocoyam production will be greatly reduced in Hawaii, especially under high-emission scenarios. Thus, changes in the cocoyam output may occur given a change in the climate; reduced or delayed rainfall, which is frequently noticed in recent time. In any given scenario, a larger, faster or more radical change in the weather element may well result in vegetation stress, rapid plant loss (in this case fall in cocoyam output) [20]. However, a mild increase in precipitation and warmth will bring about an improved plant growth and thus cocoyam output and the subsequent sequestration of airborne CO₂. It was on this premise that this study was borne; to further investigate the nature and extent of these stresses on cocoyam production and resilience building strategies among cocoyam farmers in Nigeria.

2. Methodology

2.1 Study area

The study was conducted in Nigeria. Nsukka area of southeastern Nigeria (Figure 1) was specifically selected because of the high concentration of cocoyam production and high level of its utilization in the area. Nsukka has a total population of 309,633 people [21], and is pojected to be 4832,56 by 2023 [22]. Primary data were collected with the aid of structure questionnaire from the cocoyam farmers. The prominent climatic seasons in the area include rainy season, lasting from April to October and the dry season lasting from November to March, the average rainfall is 1579 mm per annum, whereas the average temperature is 24.9°C [23]. The vegetation of the area is derived savannah. The primary occupation of the people in the area is farming; and agricultural production constitutes a major source of income for a greater percentage of the population.

Figure 1.

Showing area of study in Nigeria.

Cocoyam in Nsukka and in many areas of South Eastern Nigeria, is known to be the most important staple crop with the most varied local uses of all the root crops. This is because, apart from meeting immediate food need, it is always cooked, sliced and dried (called ‘Echicha’) and preserved to last throughout the year till the next harvesting season and used to blend several other local food stuffs into different kinds of delicacies, to bridge the gap between time of abundance and scarcity of other food sources, thus it is refered to as a food security crop.

2.2 Sampling procedure

Random sampling was adopted in the selection of respondents. The method involves random selection of three towns from the area. From the towns, 20 cocoyam farmers were randomly selected from a frame of cocoyam farmers prepared with the help of the local farmers’ organizations in the towns, making a total of 60 farmers in 2010 and 60 in 2017.

2.3 Data collection

Data were collected with the aid of pre-tested questionnaire focusing on the socioeconomic characteristics of cocoyam farmers, vulnerability of cocoyam production to climate change in the area, effects on productivity, adaptation strategies in use and impediments to adaptation. Secondary data of historical cocoyam yield per hectare in Nigeria from 1961 to 2016 were collected from FAO statistical data base.

2.4 Method of data analysis

Data were analyzed using descriptive statistics; tables, pie charts, bar chart, graphs and mean score (Likert-type scale rating). A Likert scale is a psychometric scale in survey research. When responding to a Likert questionnaire item, respondents specify their levels of agreement with respect to the extent of the impact of the different kinds of phenomena on their farming activities. The average extent agreed upon is determined by the summation of the different values of a 5-point Likert-type scale in the case of this study (To a very great extent = 5, To a great extent = 4, To some extent = 3, To a little extent = 2, and To no extent = 1). The mean score (MS) of the respondents was computed as: (5 + 4 + 3 + 2 + 1)/5 = 3 cut off point. Based on this, any score below 3 (MS < 3) is taken as a weak factor and may not be considered, while those with mean score above 3 (MS > 3) is taken as strong factor and considered to have impact on the farmers.

3. Results

This section presents the results of the study in different subsections as shown below.

3.1 Trends in cocoyam production

An analysis of the trends in cocoyam production is presented below. For the years 2007 to 2009 in the study area Figure 2 shows a declining trend in output of cocoyam from 2007.

Figure 2.

Average output of cocoyam (tonnes) per farmer for years 2007, 2008, 2009. Source: Field survey, 2010.

In 2009, output was 73tonnes less than that of year 2008 and about 105 tonnes lesser compared to year 2007. This result is in resonance with the trend analysis of cocoyam yield from FAO statistical database (Figure 3).

Figure 3.

Trend analysis of the yield of cocoyam in Nigeria (1960–2016).

The result showed that the yield of cocoyam per hectare rose to an unprecedented pick in 2005 and started a gradual drop which continues to as low as 4mt ha⁻¹. More revealing is the fact that this result agrees with the result of the field study on the time the farmers started noticing the problems with cocoyam production, as is shown in Figure 4.

Figure 4.

Distribution of respondents according to year sudden decline started. Source: Field survey, 2010.

The result in Figure 4 indicates that about 90% of the respondents indicated that the sudden decline in cocoyam output occurred in the year 2009. This finding resonates with the result from the trend analysis of the FAO data (Figure 3) and agrees with the period the problem of acid rain was reported in the country and therefore in agreement with farmers’ attribution of the problem to acid rain. This finding is in agreement with those of Ume et al. [24] and Ukonze [25].

3.2 Nature of pollution and climate change impact on cocoyam

Analysis of the nature of pollution and climate change impact on cocoyam are as presented in Table 1 and Figures 5–7.

How it occurred	Percentage (Frequency)
Noticed leaves of cocoyam appeared as if hot water was poured on it after which they turn brown/yellow and gradually eaten up from either the middle or from edges of the leaves until there was no leave left on the plant	75 (45)
Do not know	23.3 (14)
Evil spirits	1.7 (1)
Total	100

Table 1.

Distribution of respondents according to how unusual effect occurred.

Source: Field Survey, 2010.

Figure 5.

(a) Showing the effect of acid rain on cocoyam leaves (picture taken on 5th may 2010 in Nsukka, Nigeria). (b) Cocoyam tubers.

Figure 6.

Nature of effects on cocoyam leaves. Source: Field data 2017.

Figure 7.

Nature of climate change impacts on cocoyam tubers. Source: Field survey 2017.

Table 1 shows that about 75% of cocoyam farmer in the area said the unusual effect occurred during the period acid rain was reported in 2009, they noticed that leaves of cocoyam appeared as if hot water was poured on them after which they turned brown/yellow and gradually died back (Figure 5).

As a result, most of the cocoyam plants die prematurely in the field before they are matured for harvesting. This finding is not far different from that also found in more detailed analysis in 2017 about the nature of impact on the leaves and tubers of cocoyam, as in Figures 6 and 7.

The results reinforce earlier findings indicating the issue of bleaching of the leaves of the cocoyam plant which results in the poor yield and small tubers (Figure 7).

3.3 Extent of climate change impact on cocoyam production

To verify if the afore-mentioned phenomena are associated with climate change, a detailed assessment of the different forms of climate change impacts was done in the study area and the result is presented in Table 2.

Average extent of impact	Decision rule
= (1 + 2 + 3 + 4 + 5)/5=3	If average of individual element is > = 3, then the people agreed that climate change has impact on the particular element in the area. If not, they disagree.
Variable	Mean score	Decision
Unusual early rains that are followed by weeks of dryness	3.45	Agreed
Erratic rainfall pattern	2.93
Delay in the unset of rain	3.25	Agreed
Long period dry season	3	Agreed
Heavy and long period of rainfall	2.47
Less rainfall	3.05	Agreed
No or reduced harmattan	2.63
Long period of harmattan	2.55
Higher temperature	3.87	Agreed
Thunderstorms	1.88
heavy winds	2.17
floods and erosion	2.64
Drought	3.18	Agreed
heat waves	2.77
heavy rainfall	2.32
desertification or loss of forest resources	2.64
Increase in pests’ problems	3.12	Agreed
High rate of disease incidence	3.65	Agreed
Increase weed infestation	2.43
Loss of soil fertility	2.77
Drying up of streams/rivers	2.31
Overflowing of streams/rivers	1.23

Table 2.

Farmers’ perception of different forms of climate change impact and their extent on cocoyam production.

Source: Field Survey, 2010 and 2017.

The result shows that the farmers in the area agreed that climate change has impacted on their production in different forms; including unusual early rains that are followed by weeks of dryness, delay in the unset of rain, long period dry season, less rainfall, higher temperature, drought, increase in pests’ problems, high rate of disease incidence and so on. Furthermore, the farmers were asked to indicate whether these forms of climate change impact were decreasing, increasing or has not changed. This result is presented in Table 3.

Climate change impact	Decreasing	Percent	No change
		Increasing
Unusual early rains that are followed by weeks of dryness	0	100	0
Erratic rainfall pattern	0	95	5
Delay in the unset of rain	1.7	98.3	0
Long period dry season	1.7	98.3	0
Heavy and long period of rainfall	78.3	21.7	0
Less rainfall	10	81.7	8.3
No or reduced harmattan	8.3	43.3	48.3
Long period of harmattan	33.3	26.7	40
Higher temperature	1.7	98.3	0
Thunderstorms	43.3	5	51.7
heavy winds	48.3	21.7	30
floods and erosion	30	45	25
Drought	0	100	0
heat waves	25	61.7	13.3
heavy rainfall	90	6.7	3.3
desertification or loss of forest resources	6.7	45	48.3
Increase in pests’ problems	6.7	93.3	0
High rate of disease incidence	0	100	0
Increase weed infestation	36.7	60	3.3
Loss of soil fertility	0	100	0
Drying up of streams/rivers	15	85	0
Overflowing of streams/rivers	98.3	0	1.7

Table 3.

Directions of the impact of the different forms of climate change.

Source: Field Survey, 2010 and 2017.

Results show that climate change impact on the underlined variables which include: unusual early rains that are followed by weeks of dryness, Erratic rainfall pattern, Delay in the unset of rain, Long period dry season, Less rainfall, Higher temperature, Drought, Increase in pests problems, High rate of disease incidence, Loss of soil fertility, Drying up of streams/rivers are on the increase in the area.

3.4 Resilient building strategies to the impacts of climate change

In this section the various resilient building strategies employed by the farmers to cope with climate change effect on cocoyam are as illustrated in the Table 4.

Strategies	Used	Percent
		Unused
Purchase of water for irrigation (liters)	0	100
Mulching (kg)	23.3	76.7
Use of wetlands/river valleys (e.g. Fadama) (cost of use) (hectares)	21.7	78.3
Contour cropping across hill slopes (hectares)	3.3	96.7
Planting deeper or shallower than the usual planting depth (hectares)	88.3	11.7
Construction of drainage or dam within the farm/household (Area)	3.3	96.7
Afforestation: planting of trees (number)	23.3	76.7
Use of resistant varieties (number)	23.3	76.7
Processing crops to minimize post-harvest losses (Kg)	95	5
Expansion of cultivated land area (ha)	23.3	76.7
Increased use fertilizers, seeds (kg)	20	80
Cultivation on marginal lands	3.3	96.7
Intensive manure application (kg)	83.3	16.7
Increased weeding (ha)	20	80
Use of chemicals: herbicides, pesticides etc. (kg)	43.3	56.7
Erosion control (ha)	100	0
Move to a different site (ha)	55	45
Soil conservation practice (ha)	1.7	98.3
Shading and shelter (ha)	10	90
Change in the timing of land preparation activities	38.3	61.7
Changes in planting dates	38.3	61.7
Changes in harvesting dates	13.3	86.7
Multiple cropping	93.3	6.7
Mixed farming (crop and animal production)	70	30
Relay cropping – planting and harvesting in succession	10	90
Use of different varieties	18.3	81.7
Use of different planting dates	30	70
Intercropping – main crops planted with subsidiaries at low densities	63.3	36.7
Reducing your animal stock	18.3	81.7
Culling of infected animals	8.3	91.7
Crop replacement	43.3	56.7
Change from crop production to animal rearing	5	95
Change from animal production to crop production	11.7	88.3
Agro-forestry practice	16.7	83.3
Change from production to marketing of agricultural products	10	90
Total change from farming to other occupations	10	90
Replanting	43.3	56.7
Prayers	80	20

Table 4.

Resilient building strategies to the impacts of climate change among cocoyam farmers.

Source: Field survey, 2010 and 2017.

Results indicate that the most prominent strategies adopted by the farmers are planting deeper or shallower than the usual planting depth, processing crops to minimize post-harvest losses, intensive manure application, erosion control, multiple cropping, move to a different site, mixed farming and intercropping – main crops planted with subsidiaries at low densities.

3.5 Factors affecting the adoption of different resilience building practices

This section presents the factors that affect the adoption of adaptation practices in the area. The mean score of each constraint was determined using a five-point Likert scale with the following ratings; To a very great extent = 5, = 4, To some extent = 3, To a little extent = 2, and To no extent = 1), giving a mean of 3, as shown in Table 5.

Average	Decision rule
3	If the average of the variable is 3 and above, it means that such variable is an important constraint to adaptation in the area, but if lower it is not an important constraint
Strategy	Mean score	Decision
Limited availability of land for farming	2.63
High cost of farmland	2.27
Inherited system of land ownership	2.75
Communal system of land ownership	2.1
Poor access to information sources	2.33
Non-availability of credit facilities	2.52
High cost of irrigation facilities	2.48
Non-availability of farm inputs	2.75
High cost of fertilizers and other inputs	2.38
Inadequate knowledge of how to cope	2.53
Non-availability of improved varieties	2.2
High cost of improved varieties	2.05
Non-availability of farm labour	2.2
High cost of farm labour	3.08	Agreed
Lack of access to weather forecasts	2.26
Poor response to crises related to climate change by the government’s agencies and interest groups	2.42
Non-availability of storage facilities	2.35
Limited income	3.05	Agreed
Non-availability of processing facilities	2.83
High-cost processing facilities	2.62
Traditional beliefs/practices e.g. on the commencement of farming season etc.	1.25

Table 5.

Factors affecting adoption of different adaptation practices.

Source: Field Survey, 2010 and 2017.

Results show that the major constraints to adoption of adaptation practices in the area high cost of farm labour having an average of 3.08 and limited income scores an average of 3.05. The farmers complained that getting farm labour is quite expensive and they have limited income to pay for such.

4. Discussion

The results of this study show that the progressive decline in the production of cocoyam since the mid 2000 are associated to different kinds of abiotic stress on the crop. A detailed analysis of the trend in the production of the crop reveals that there has been a disturbing trend in its output. Both results from field interview and that of the trend analysis of FAO data set agree, indicating a declining trend in output of cocoyam from 2007 (Figures 2 and 3). The FAO statistics shows that the yield declined from an unprecedented height of about 8mt ha⁻¹ in 2005 progressively to as low as 4mt ha⁻¹ in 2016 and this trend has continued to date. This disturbing trend also resonates with the findings of Talwana et al. [13] about a declining trend in the output of cocoyam in Uganda; which coincides with the same period of this decline in Nigeria. This finding is also supported by the position of experts and stakeholders in Cocoyam value chain in 2017, who lamented the declining trend in cocoyam output over the years [26]. They also called for improved technology and practices that would mitigate the observed adverse effects of climate change on the crop. This position was made in a workshop targeted at assisting cocoyam farmers to sustainably adapt to the severe effects of climate change in Nigeria, The workshop was sponsored by the Association of Commonwealth Universities, African Academy of Sciences and UK Aid, under the Climate Impact Research and Leadership Enhancement programme, focused on: “Climate Change Adaptation and Constraints Faced By Cocoyam Farmers in Southeast Nigeria” and held at the National Root Crop Research Institute (NRCRI), Umudike, Abia State, with participants drawn from universities, agriculture research institutions and farmers groups, among others.

There is therefore evidence that something is wrong with cocoyam production in the tropics. This trend has brought untold hardship on the households in the cocoyam production areas of Nigeria. This is because the crop has formed a part of daily staple for the households, especially in the rural areas. Therefore, the shortfall has brought about unnecessary food security crisis among the households. It was for this reason that this stud was initiated to investigate the nature and extend of the problem.

Further analysis showed that this phenomenon became very prominent in the later part of 2000. Specifically, they believed it was in the year 2009, which is also in agreement with the FAO data. Coincidentally, these findings agree with the period the problem of acid rain was reported in different parts of the country [27, 28, 29], and therefore in line with farmers’ attribution of the problem to acid rain. The severity of the frustration occasioned by this problem is depicted in the words of Hassan, thus.

“As the call to battle hunger in the world continues to grow, another dimension to the battle against climatic forces has emerged in Nigeria in the form of acid rain threat. Acid rain presents yet another challenge to smallholder farmers especially, because it has the potential of destroying crops in the farms thereby affecting the total yield at the end of the farming season” [28].

Also describing the nature of the problem, most of the farmers indicate that cocoyam crops in the field die before they are matured for harvesting. In their words;

“cocoyam leaves appear as if they are bleached with hot water, after which they turn brown/yellow and gradually eaten up from either the middle or from edges of the leaves until there is no leave left on the plants”.

And this happens usually after rainfall and is the case in most parts of eastern Nigeria, where cocoyam is predominantly utilized. The farmers linked this scenario to acid rain that has been reported in Nigeria. Acid rain results from air pollution and climate change. Acid rain come about due to sulfur dioxide (SO₂) and nitrogen oxide (NO_x) gases and their particulate matter derivatives from industrial and automobile emissions, they react with falling water to make it acidic. Acid rain does not usually kill plants directly. Instead, it weakens the plants by damaging their leaves, limiting the nutrients available to them, or exposing them to toxic substances slowly released from the soil. Quite often, injury or death of trees is a result of these effects of acid rain in combination with one or more additional threats [30]. As a result of this scenario output declined from about 1.8 tonnes to about 0.6 tonnes per household from 2007 to 2009 respectively.

Further analysis in 2017 also corroborates the 2010 findings with more detailed description of the effects on the leaves and tubers of cocoyam; bleaching of cocoyam leaves, die back, smaller tubers, early decay of the tubers and decline in the quality and taste of the tubers. Because of these problems most of the cocoyam plants die prematurely in the field before they are matured for harvesting.

Analysis of the experiences of the farmers concerning the problem shows that the farmer highlight some climate change related factors that affect their cocoyam production, The different forms; that affect their production include unusual early rains that are followed by weeks of dryness, delay in the unset of rain, long period dry season, less rainfall, higher temperature, drought, increase in pests problems and high rate of disease incidence. These phenomena were shown to have mean scores above 3, which is the cut-off point that shows the factor which important from the mean scores’ analysis.

Particularly, the farmers complained of the problems of delayed unset of rain and early unset of rainfall that is followed by long period of dryness that have become rampant in recent times. These conditions are not favorable for cocoyam production, as the crop require high amount of moisture for optimum yield. More so, some local farmers who planted their cocoyam seedlings after the first and second send rains when asked, complained of unexpected rise in insolation and temperature of the soil which resulted either in the cooking of the tubers in the soil, destruction of some seedlings newly planted or delayed germination and/green leaf formation. Thus, the issue of poor adoption of improved technology or poor cultural practices, pest and disease become secondary among the causes of decreased output as has been suggested b some scholars. These findings therefore indicate that climate change interacts with other abiotic factors to predispose the cocoyam and other crops in the country to stress as has also been reported by other scholars [31].

With respect to the resilient building strategies adopted by the farmers to cope with some of these challenges, the study shows that the farmers have tried different approaches like planting deeper or shallower than the usual planting depth, depending on the crop variety to reduce the effect of scorching sun or excessive flooding. To prevent decay of the tubers, the farmers are forced to process them into more durable forms which are stored for future use. To boost crop yield, the farmers practice intensive manure application, this because the felt that the cause of the poor yield was due to poor soil fertility. They also practice multiple cropping/mixed cropping as a form of crop insurance, so that if the cocoyam crop fails they can harvest the other crops. This is practices as a traditional way of ensuring against total crop failure. The also abandon the fields where their crops fail and, move to a different sit, with the hope that the new sites would be free from the disease that killed their crop or are more fertile than the previous sites. The practice mixed farming and whereby the also keep animals as a means of insurance.

On the other hand, the farmers pointed out some of the challenges that militate against their ability to effectively cope with the challenges as high cost of farm labour and limited income. They believe farm labour is expensive, and they have limited income to pay for labour and the required farm inputs that they require in the production process, like fertilizers and other agrochemicals. The trio; farm labour, credit and inputs are the major limiting factors in agricultural production in Nigeria aside from the problems of climate change. They are often not available, where they are; they are limited, expensive or require very stringent bureaucratic bottlenecks to access, in the case of credit. So, farmers resort to using family labour to do the much they can. The buy the fertilizers and chemicals they can afford and therefore do not use them in the recommended rate for optimum results. Thus, they continue in the vicious cycle of low productivity and poverty.

5. Conclusion and recommendation

The study investigated the problem of the declining trend in cocoyam production since the mid-2000. Preliminary investigations show that farmers were experiencing poor yield and were gradually moving away from the cultivation of cocoyam to other crops. The results indicate that air pollution, which results in the production of acid rain and climate change combine to limit the productivity of cocoyam in the study area.

This problem has resulted in low output of the crop and reduced welfare of the households who depend on the crop for their livelihood. Though the farmers are making genuine efforts to cope with the situation, but their efforts are limited by access to the required labour, capital, inputs and other necessary support that will assist them in building resilience to the problem.

We therefore posit that the threat to cocoyam has assumed a frightening dimension. Thus, there is need for more detailed integrated research to unravel and solve the problem of cocoam production in Nigeria. Concerted efforts is also needed to help the farmers copped with the present problems which are not the making of theirs. If nothing is doneurgentl to stem this negative tide cocoyam is heading towards extinction. Policies that target input provision, reduction in greenhouse gas emission and increase in farmers’ share/income must be encouraged as these will help build their resilience to the impact of climate change.

Acknowledgments

We wish to thank friends and family for their patients and kind supports during this research.

Conflict of interest

None.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.