Nigeria is reported to be the world’s largest producer of yams, accounting for over 67-69 per cent of the world production, with her neighboring Ghana coming second with a distant 10% and Côte d’Ivoire third with 9.2% (Food and Agriculture Organization (FAO), 2021 and Effiong and Iheme, 2024). According to the Organization and Federal Office of Statistics (FOS) (2021), Nigeria produced 50.05 million tonnes of yam from 1.8 million hectares, representing 73.8 per cent of total yam production in Africa and with a market value equivalent to US$14.654 billion. Yam is in the class of roots and tubers that is a staple of Nigerian and West African diet, which provides some 200 calories of energy per capital daily [International Institute for Tropical Agriculture (IITA), 2019 and FAO, 2021].  According to Amaefula (2021) in many yam-producing areas in Nigeria, it is said that “yam is food and food is yam”. The author further stated that yam has an important social status in gatherings and religious functions, which is assessed by the size of holdings one possesses. However, in spite of the reported status, the production of yam in Nigeria is substantially dwindling when juxtaposed with the growing demand at its present level of use. Studies have attributed this dwindling production to resource use related problems (Ettah and Ani, 2017 and Ume et al., 2020).
       
Yam is grown on free draining, sandy and fertile soil, after clearing the first fallow. Land is prepared in the form of mound or ridge or heap of 1 metre (3 ft 3 inch) height, depending on the hydromorphic nature of the soils to make for looseness of the soil suitable to grow roots and tuber crops (IITA, 2019). The yams that are common and recommended for such soil conditions in Nigeria are white yam or white guinea yam (Discorea rotundata) and water yam or yellow yam (Discorea alata) and planting done by seed yam or cut setts from tubers. Ekunwe et al. (2008) noted that a day before planting, the tubers have to be subjected to treatment with wood ash or a fungicide (thiabendazole) to prevent damage to the soils. The setts are planted at an interval of  15-20 cm (5.9-7.9 in) with the cut face facing up. Mulching may be necessary during the early planting (January-March) with dry grass or plant debris and manual weeding by hoeing is done three or four times depending on the rate of weed growth (Ume et al., 2020). Two Stakes, each of about 2 metres (6 ft 7 inch) height are used for staking the plants to vine over it; one for two plants with the other used for bracing with the adjacent stake.
       
Amaefula (2021) posited that although the crop is grown widely in Nigeria, the area where it is grown most are the Benue State (land area of 34,059 km²) and the neighboring Cross River State (land area of 31,065 km²), the study area. In these areas, the crop is grown with labour-intensive practices on small land holdings (mostly less than 3 ha). In these states the size of the yam farm or the tonnage of yams produced becomes the social status of that farmer. While yam production issues have been stressed on agronomical practices, a research study carried out by Ekunwe et al. (2008) on resource-use efficiency in yam production with small farm holdings, shows that land, labour and material inputs (fertilizers and chemicals) have a significant bearing on the yield of yam in the region.
       
Efficiency analyses are issues of interest given that the overall productivity in agriculture is directly related or dependant on it (Dash et al., 2025 and Ettah and Kuye, 2017). Fateh et al. (2024) and Yasodha and Chinnusamy (2025) noted that the analysis of efficiency is generally associated with the possibility of farm producing a certain optimal level of output from a given bundle of resources or a certain level of output at a least cost. Ettah et al., (2022) stated that resource efficiency is concerned with the relative performance of the processes used in transforming given inputs into output. Jinghan (2009) noted that basically, three types of resource efficiencies combine to achieve efficiency in agriculture: Technical efficiency, the ability of farms to employ the best practices in the production process, so that not more than the necessary amount of a given set of input is used in producing the best level of output. Agbachom et al., (2023) noted that allocative efficiency is the choice of optimum combination of inputs consistent with relative factor prices and economic efficiency which measures the overall performance of a farm and is equal to the product of technical efficiency (TE) and allocative efficiencies (AE).
       
The constraint to the rapid growth of food production seems to be that of low efficiency as a result of inefficient allocation of available farm resources (Ettah et al., 2024, Kumbhar et al., 2026 and Singh et al., 2026). The question of how efficient rural farmers use their farm resources with respect to their socio-economic attributes is of considerable interest to agricultural economics (Agbachom et al., 2019). Efficient farms make better use of existing resources and produce their output at the lowest cost (Ettah et al., 2022). The justification for this study stems from the fact that both the empirical and analytical inclinations to resource use in yam production accepted that farmers are insufficient and inefficient in the use of the resources resulting to low production (Ettah et al., 2024). Yam production is of interest as an enterprise that will increase income, employment and standard of living in rural and urban areas (Ekunwe et al., 2008).
       
The increasing importance of yam as a food crop in Nigeria calls for efforts to increase its production and productivity. The study is further justified by the fact that yam resource use study has emerged as an effective strategy to achieve goals of sustainable yam production, transformation and development, because of its ability to provide solutions to non-sustainability of production (Ume et al., 2020). This study is poised also to identify and provide better information about the variables that may be responsible for the difference in levels of efficiency of resource utilization of yam farmers. A study of this nature is likely to give direction to adjustment in resource use and to offer alternative methods of production in order to increase farmer’s production and productivity in the study area. The study is predicated on these resource use problems and the above stated justification of study and hence is set to realize the following specific objectives:

• Determine the efficiency of resource use in yam production in the area.
• Examine the factors that influence efficiency of resource use in yam production in the area
       
Based on the above objectives, the following null hypotheses were tested:
• Yam farmers in the area are efficient in resource use in yam production in the area
• There are no factors influencing resource use in yam production in the area. 

Study area
 
Cross River State, Nigeria is the study area. The state was purposively chosen for this study because of the peculiarity of this research problem in the area and the familiarity of the researcher to the area, factors that facilitated data generation. The State is bounded by the States of Benue in the North, Ebonyi on the West, Akwa Ibom on the South west. It is bordered on the east by the Cameroon Republic and fronts the Atlantic Ocean on the South (Boundaries Commission, Newsletter, 2021). Cross River State lies between latitude 4°15′ North and 7°00′ North and longitude 7°15′ East and 9°30′ East. The land area of Cross River State is about 7,782 square miles or 20,156 square kilometers and the population standing at 2,888,966 persons (NPC, 2011). Following an annual growth rate of 2.9%, it is expected that the population of Cross River State will hit over 3,900,000 million people by the year 2023. The climate of the state is characterized by two distinct seasons-the dry and wet seasons. The dry season spans from November to late March, while rainy season spans from April to October with a short spell in August called  August break and has mean annual rainfall between 1,300 mm to 3,000 mm (Cross River State Tourism Guide, 2021).
 
Sampling procedure
 
The population for this study comprised yam farmers from Cross River State, Nigeria. Multistage random sampling technique was used to select respondents for the study. In the first stage, three local government areas each were selected randomly from each of the three agricultural zones of the State. This gave a total number of nine local government areas in the sample. The second stage involved the random selection of three yam farming communities from each of the nine local government areas previously selected making a total of twenty seven yam farming communities. The third stage involved a random selection of four yam farmers from each of the twenty-seven communities making a total 108 respondents for the study.
 
Data collection
 
Data required for this study were generated from primary sources. The primary data were collected using a set of pre-tested structured questionnaires and were administered by well-trained enumerators (farmers), who were conversant with the selected locality. A pilot study was conducted where enumerators were used for pre-testing of the questionnaire. This was to avoid inconsistency and incomplete response and also ensure clear understanding of the instrument. The instrument was further validated by pilot testing and passing through experts to ensure that it possessed both face and content validity. In other to check the consistency of the measuring instrument over time, reliability test was conducted using the test-retest method. The same questionnaire was given to the same respondents at two points in time (an interval of seven days) and the scores compared.
 
Methods of data analysis
 
Efficiency of resource use was analyzed from the coefficients of the Stochastic Production Frontier model as used by Ettah and Kuye (2017). The empirical model of the Stochastic Production Frontier for yam farmers was specified as:
 

  Yij = β₀ + β₁ ln X₁ij + β₂ ln X₂ij + β₃ ln X₃ij +β₄ ln X₄j + β₅ ln X₅ij + β₆ ln X₆j + U_ij - V_ij              ...(i)     

                                                                                                                                                                                                                      
Where:
Y = Total farm output of yam (tones).
X₁ = Quantity of fertilizer used (tones).
X₂ = Capital inputs (tones).
X₃ = Labour (mandays).
X₄ = Farm size (ha).
X₅ = Agrochemicals (litres).
X₆ = Yam seed (kg).
V_ij = Random error with normal distribution N (0, δ2).
U_ij = Non-negative random variables called technical inefficiency effectsln = The natural logarithm.
β₀- β₅ = Parameters to be estimated.
i = i^th observation.
j = j^th observation.
V_ij = Assumed to be independent and identically distributed normal random variables with mean zero and variance, d2.
U_ij = Assumed to be independently distributed.
       
Multiple regression model was employed to determine factors that influence efficiency of resource use in yam production as used by Ekunwe et al., (2008). The general multiple regression model in its implicit form is expressed as: 
 

   Y = f (X₁, X₂, X₃, X₄, X₅, X₆, X₇, X₈, X₉ +e)             ...(ii)     

                                                                 
The explicit forms of the four models tested are expressed as follows:
 

Linear Y = α + β₁ X₁ + β₂ X₂ + β₃ X₃ + β₄ X₄ +β₅ X₅ + β₆ X₆ + …… β₉ X₉ + e       ...(iii)
                                                                                              
Double-log: lnY = lnα + β₁lnX₁ + β₂lnX₂ + β₃ lnX₃ + β₄ lnX₄ + β₅ lnX₅ + . . . + β₉ X₉ + e      ...(iv)  
                                                                                                                       
Semi-log: Y = lnα + β₁lnX₁ + β₂lnX₂ + β₃ lnX₃ + β₄ lnX₄ + β₅ lnX₅ + . . . + β₉X₉ + e       ...(v)
                  
             Exponential: lnY = α + β₁ X₁ + β₂ X₂ + β₃ X₃ + β₄ X₄ + β₅ X₅ + β₆ X₆ + …… β₉ X₉ + e        ...(vi)        

          
Where:
Y = Quantity of yam  (tonne).
X₁ = Sex (dummy: Male = 1, Otherwise = 0).
X₂ = Age of farmers (years).
X₃ = Educational level (years).
X₄ = Farming experience (years).
X₅ = Farm size (hectares).
X₆ = Household size (number).
X₇ = Marital status (dummy: Married =1; Otherwise = 0).
X₈ = Farm income (N).
X₉ = Membership of cooperatives (dummy: Member =1; otherwise = 0).
e = Error term.

Efficiency of input utilization by yam farmer
 
Table 1 shows the efficiency of resource use of six inputs: fertilizer, capital inputs, labour, farm size, agrochemical and yam seeds. This was estimated by taking a ratio of the Value of Marginal Product (VMP) and unit price of inputs (Jinghan, 2009). The VMP is estimated by taking the product of the regression co-efficient (b) and unit price of yam.  Fertilizer and agrochemical were underutilized due to scarcity and high cost of acquiring them, this result conforms to that of Ume et al., 2020). Farm size (0.52) was also underutilized probably due to the over fragmentation of land and the communal land tenure system which does not allow for large ownership of farm land in the study area. Finally, yam seed (0.21) was also underutilized and can be attributed to cost and inaccessibility to high yielding and improved yam seedling in the area. The result is in tandem with that of Ekunwe et al., (2008). For all the underutilized inputs: fertilizer, farm size and agrochemical any unit increase in their use will lead to further increase in the output of yam.


       
Labour (0.04) was over utilized, an indication of excessive use of family labour and cheap hired labour in the area.  Capital inputs had an efficiency ratio of -0.02 and hence over utilized and could follow from the fact that there is abundance of these inputs to the yam farmers. The capital inputs are used in the area are always simple and unproductive farm tools like cutlass, pans, knife, hoe, diggers, etc. their simple and their less expensive nature makes them available and hence over utilized. This finding agrees with that of Ettah et al. (2022) that over utilization of capital inputs is because of abundance due to their simple and less expensive nature. The over utilized resources amounted to economic waste of productive resources, with their alternative uses unattended to.
 
Factors that influence efficiency of resource use in yam production
 
Factors influencing efficiency of resource use in yam production were estimated using the ordinary least squares multiple regression technique. The result is presented in Table 2, the Double-log functional form provided the best fit and was chosen as the lead equation. The R² value of 0.6148 indicated that about 61.48 per cent of the variation in yam output is as a result inefficient resource use. Sex (X₁), household size (X₆) and farm size (X₅) were found to be negatively and statistically insignificant or inversely related to efficiency of resource use in yam production in the study area.  All other variables: education (X₃), age (X₁), farming experience (X₄), marital status(X₇), farm income (X₈) and membership of cooperatives (X₉) were positive and significant to influence the efficiency of resource use in the area, at various levels of significance. The implication of this finding is that the more educated the farmer is, the higher his capacity to adopt technologies and measures that will mitigate against resource use inefficiency. The educated farmer is also better positioned to seize the opportunity offered by extension services and other stakeholders in agriculture to improve on the efficiency of resource use in yam production. High literacy rate ceteris paribus would enable yam farmers adopt efficient resource use technologies that will lead to more efficiency (Effiong and Iheme, 2024 and Amaefula, 2021).


       
The relationship between age and efficiency of resource use in yam production shows that the older the farmer the lower efficiency of resource use, this result is in line with that of Ettah and Ani (2017). This may be attributed to fact that older farmers tend to give up their resource use practices as they get older for their traditional practices. The more the farming experience the more farmers in the area are efficient in resource use. This is because with more years of experience, farmers are able to acquire more knowledge and skills of efficient resource use. The marital status is an indication that married farmers are more efficient in resource use. There is a tendency of the farmers (including their children) to collaborate in efficient use resources in the farm. The larger the farm income, the more money available to the farmers that can be deployed in efficient resource use practices (Ume et al., 2020). Result of cooperative membership shows that the variable affords farmers the opportunity to pull resources together including knowledge of efficient resource use. Participation in cooperative helps in sharing of vital information relating to resource use practices that could boost effective and efficient resource use, hence the positive relationship with resource efficiency (Effiong and Iheme, 2024).
 
Test of hypotheses
 
The null hypothesis that yam farmers in the area are efficient in resource use in yam production in the area is hereby rejected; this is because efficiency ratio of these production inputs shows that none of them was efficiently used within the limits of statistical error. Equally rejected is the second hypothesis that there no factors influencing resource use in yam production in the area, this is because result of study showed that about 61.48 per cent of the variations in yam output is as a result of inefficient resource use arising from socio economic attributes of the farmers.

Efficiency of resource use by farmers is an important aspect of farm management, as it is directly related to farm production and productivity and hence profit of farmers.  Efficiency of resource use of six input that are basically used for yam production in the area: fertilizer, capital inputs, labour, farm size, agrochemical and yam seeds and factors influencing efficiency of resource use in yam production were studied. The efficiency ratio of these production inputs shows that none of them was efficiently used within the limits of statistical error. For the factors influencing efficiency of resource use in yam production, Sex, household size and farm size were found to be negatively and statistically insignificant or inversely related to efficiency of resource use in yam production in the study area. The remaining variables education, age, farming experience, marital status, farm income and membership of cooperatives were positive and significant to influence the efficiency of resource use in the area, at various levels of significance.
       
Based on the result of this study, the following recommendations were suggested: Yam farmers in the area should decrease their rate of use of capital inputs and labour since these inputs in the analysis are over-utilized. Rather they should be channeled to other alternative enterprises. Variables like: education, age, farming experience, marital status, farm income and membership of cooperatives should be improved and encouraged since they were positive and significant to influence the efficiency of resource use in the area.

The authors duly acknowledge the Department of Agricultural Economics, University of Calabar, Nigeria, for providing necessary facilities and guidance during experimentation.
 
Author's declaration
 
All authors have accepted responsibility for the content of the manuscript, reviewed all results and approved the final version. Conceptualization: O.I. Ettah, Edet, E.O.; data collection: Ettah, G.I., Elemi, E.D. Statistical analysis: Uwah, E.D., Igiri, J.A., Agbachom, E.E.; data interpretation: Edet O.G., Fakuta, B.A., Akwo, T.C.; writing the first draft: Ettah, O.I., Offem, C.O.; Manuscript editing and reviewing: Ofoha, D.C., Effiong, C.A.; Project administration: Elemi, E.D, Ettah, G.I., AEE. 

There was no conflict of interest known to the authors in this research work.