Project Body:


Declining productivity of yam in Nigeria highlighted the need for a study to determine both the effect of fertilization on yam (Dioscorea spp.) yield andhe best agronomic management options available for stabilizing yam productivity, via the modeling of yam growth and development. This study addressed the above issues by carrying out a research which analyzed the problem of yam production in Nigeria. A questionnaire was administered to elicit information from respondents in the study area. The data collected from the respondents were analysed using the simple percentage analysis and recommendations were made on the problems highlighted.


Background to the study

Statement of problems

Research question

Objective of study

Significance of study

Scope of study

Limitation of study

Definition of terms

CHAPTER TWO  Review of Literature    

Yam Agricultural System

Environmental requirement





Fertilizer application




Study population

Sample size

Sample techniques


Method of data collection

Analysis of data


Data presentation, analysis and interpretation


Summary, conclusion and recommendation

Summary and major findings

Costly labour

Discussion on the findings








Yams (Dioscorea species of family Dioscoreaceae) constitute a multi-species crop that is important for food, income and socio-cultural practices. The most dominant production and consumption zone for yams in the world is in West and Central Africa. Yam plays important roles in the nutritional, social, cultural, and economic life of the people in the yam belt of Africa. Nutritionally, yam is a major staple providing food for millions of people in the world. It is eaten in different forms as fufu, boiled, fried, and roasted (Aidoo, 2009). In Ghana, yam constitutes about 13% of household food budget in urban centers (Aidoo, Ohene-Yankyera, Marfo and Blaise, 2009). Economically, yam is important in the local commerce in West Africa and accounts for about 32% of farm income (Chukwu and Ikwelle, 2000). The crop serves as a major source of foreign exchange earnings and is used as raw materials for starch industries and pharmaceutical companies (Amanze, Agbo, Eke-Okoro and Njoku, 2011). As the leading exporter of yam in the world, yam exports contribute significant foreign exchange earnings to the Ghanaian economy (Ohene-Yankyera, Aidoo and Ohenewa-Tawiah, 2011).

        The entire production, processing and marketing chain of yam offers vast employment opportunities for millions of people. The supply of yam offers prospects for income generation due to the number of people involved and the value attached to it. The marketing system, which affects the prices received by farmers and those paid by buyers, has a profound impact on sustainable food security (FAO, 2003).

        Yams are members of the genus Dioscorea and belong to the family Dioscoreaceae. Yams are dioecious plants and produce tubers and bulbils (aerial tubers) of economic importance. The stems are viny, leaves are cordate or ovate, tubers mostly cylindrical and rich in

carbohydrate which make them suitable to be used as food (Mandal,2003). Tuber development is an evolutionary adaptation to a dry season, when leafy shoots die back and tubers become dormant (Purseglove,2002). During the evolution of the edible Dioscoreas, the thickening and lobbing of the ancestral rhizome gave way to a well developed tuber system (Burkill,2000). In most species, they are renewed and produced annually, while in others they are perennial. As crops, yams are harvested every season and replanted using tuber pieces to regenerate the plant. Unlike other tropical root and tuber crop species, once harvested, yams can be stored for 4-6 months in ambient tropical conditions without significant deterioration of their nutritional properties. Tubers are also often dried and later milled into flour for reconstituting as a stiff paste (fufu), which is highly appreciated in West


The family Dioscoreaceae comprises six genera but the genus Dioscorea is the major one. About 600 species of Dioscorea have been identified, among which 12 species are edible (Coursey,2006). Within this genus, edible and marketable species are: Dioscorea rotundata (white yam or Guinea yam), Dioscorea alata (greater yam or water yam), Dioscorea esculenta (lesser yam or Asiatic yam), Dioscorea bulbifera (aerial yam or potato yam) and Dioscorea cayenensis (yellow yam) which produces edible tubers and bulbils (aerial tubers located in the axils of leaves).

Some Dioscorea species, like floribunda and composite, are appreciated due to their high tuber content of steroidal saponins, being used in the manufacturing of oral contraceptives, sex hormones and cortisone (Purseglove,2002; Applezweig,2007). The drug yams are still essentially wild species (Coursey,2006). The English term “yam” is most likely derived from the Portuguese word, ynhame, found in early documents, itself being the transcription of niam, the word used in the Malinke language spoken widely through the Guineas, Sierra Leone and Ivory Coast (Coursey, 2006).

        Yams means many things to most people. To the farmers it is edible root tuber crop, which generate his income for the up-keep of his family and himself. It has helped raised the standard of living over the years. The oxford dictionary describe yam as a starch tuberous root largely replacing potato as a staple food in many tropical and sub-tropical countries of the world. Yam belongs to the botanical genes discovered, but there are very many species of great importance in West Africa.

The white yam (Discoreal rotonlata) 

The water yam (Discoreal alata)

The yellow yam (discoreal caganesis)

Lesser yam (D. bulbfery)

Trifoliate or three leave yam (D. dumetorum)


        Falling yam productivity has fuelled calls for increased research activities in yam – a crop that serves as staple food to millions of people in Africa. There are great differences in yield between individual countries (FAO, 2007), but for all countries, the average yield level is far below the potential one, which has been estimated (Gurnah,1974; Martin,1972) at 15-20 t for dry tubers ha-1 yr-1 (equivalent to 60-75 t ha-1 yr-1 on a fresh weight basis). One major constraint highlighted for its contribution to declining yam productivity is soil fertility degradation, due to nutrient depletion by leaching, and erosion, and the loss of organic matter from most soils in the savannah zone of Edo State. With increasing demographic pressure, land use intensity and reduced forest cover, suitable land for yam cultivation becomes gradually scarcer (Carsky et al., 2001). In Edo State, farmers practice slash-and-burn agriculture for yam production, which places great pressure on scarce virgin and fallow land resources. Natural fallow, crop rotation with grain legumes, and mineral fertilizer are the main soil fertility management strategies practiced here. However, most farmers do not use fertilizers and manures to any appreciable extent on yams.

The edible yams are root crop groom on a field scale for the tubers. They provide staple carbohydrate food in the yam zone of west Africa, where daily consumption is 0.5, 1.0kg yam need a great deal of labour for their cultivation and to prepare them for food and they are usually expensive to buy for normal human consumption, the field or peal, sometimes after partial boiling in west Africa, they are usually eaten as pounded yam which is prepared by pealing cut up yam and boil before pounding them in a wooden mortal to produce a glutinous dough (pounded yam).

Therefore, this study sought to obtain more quantitative information on the problem of yam production and to derive growth parameters that could further be used for modeling of yam growth.


1.           Does lack of storage facilities affect yam production?

2.           Do the uncertainties of market price affect yam production in Edo State?

3.           Does lack of good road affect the production of yam in Edo State?

4.           Is consumer taste a problem facing the farming or production of yam in Edo State?

5.           Can the nature of the scarce of supply of yam tuber a problem of producing of yam?

6.           Is nutritional value a problem facing the production of yam tuber?


        Yam production in Edo State have hither to received security attention from research workers and students, the main reason for this is that people are ignorant at the importance of yam production in the state.

        One of the present day problems of yam production in Edo state has not been encouraging; the people regard the production of yam in the state as fit for only poor and the illiterate. Illiteracy is regarded as a passport to shirt and tie job in town.


        Yam is a notable for its importance in human life.

        To ensure it’s confined existence with better performance

To ensure the awareness of people to the need for development of a positive attitude towards the production of yam in Oredo Local Government of Edo State.

To improve the quantity and quality of yam production in our local government area of Edo State.

To make people understand better effective and efficient modern methods of producing yam in the state.

To find out why yam is not cultivated in lorry scale by the farmer in Edo State.

To identify the different condition favourable for yam production in Edo State.

The existence of yam is threatened by cassava production if care is not taking the survival of yam doubtfully.


        This product works is centered on the production of yam in Oredo Local Government Area of Edo State.

        The problems associated with yam production in Edo State and ways of finding solution to the problem encountered by the farmers.


        This research of work or project should be centered on definition on the problems and prospect of yam production in Edo State. However, due to the complex nature of the villages in Edo State, some selected villages in the state are Edogbo Oregbani and Asoro. 

Useful Links: