6. Pruebas en un entorno controlado para los dos programas 99
6.2. Programas de apoyo
Yam is a vital crop, not only to the domestic market but also for export. The Central Bank of Nigeria (1998, cited in Bamire and Amujoyegbe 2005) reported that yams earn an average of 32% of farmers’
gross income derived from arable crops. Yams are processed in many ways, including pounded yam (from D. rotundata, and sometimes, D. cayenensis), boiled, roasted or grilled yam, fried yam slices and yam balls, mashed yam, and yam chips and flakes (Bamire and Amujoyegbe 2005). Fresh yam tubers are also peeled, chipped, dried, and milled into flour, which is then cooked in boiling water and turned into a thick paste called amala in Western Nigeria (Oguntade et al. 2010).
2.3 G
ENERAL SEED SECTOR CHARACTERISTICSYams are usually vegetatively propagated by planting pieces of tuber. Before the minisett
technology, large ware yam tubers from previous seasons were divided into pieces called cut setts, and these were planted in the new season. This tends to increase disease in the planting materials and in the field. Moreover, the planting material is bulky and expensive. Seed yams can also be produced through the traditional system in which the yams are milked after the first six months of planting and left in the soil to allow the seed tubers to form. Milking is the practice of removing a developed yam tuber, and then cutting off the topmost part and replanting it back into the ground. In “partial sectioning” (cutting a whole ware yam tuber into four chunks) (Orkwor and Asadu 1998), farmers bury the tuber piece in fertile soil or a compost mixture. The farmers wait for the sprout to emerge, and then transplant it.
To make seed cheaper, the YMT was developed in the 1970s by the National Root Crop Research Institute (NRCRI), Abia State, Nigeria, and IITA (IITA 2013). This was later modified and relabeled as the AYMT by IITA and Diocesan Development Services (DDS), Kogi State, Nigeria (2003–2006). The AYMT was designed to address the concerns of farmers who rejected YMT because it involves various new tasks that add to the labor demand, and to address concerns with germination of small minisetts of about 25 g.
2.4 T
RENDS,
DEVELOPMENTS,
ONGOING CHANGE OF CONTEXTBrief history of change from YMT to AYMT. YMT, designed for rapid, high-volume seed yam production (Orkwor and Asadu 1998), involves cutting a ware yam into many setts of about 25 g each, dusted with pesticide and wood ash, and planted in a nursery bed for pre-sprouting. In AYMT, cut setts of about 100–150 g (later reduced to about 80 g) are dipped into a mild cocktail of chemicals (fungicide + insecticide; 100 mg of mancozeb, 70 ml of Basudin, and 10 l of water) for 5–10 min, air dried at room temperature under shade, and planted directly into the fields on the following day (McNamara et al.
2012; see Figure 4.1).
Farmers rejected YMT for two reasons: the high labor costs of planting the setts in a nursery prior to field planting, and the pieces were so small that many died (Okoli 1986). In the DFID project, the YMT was modified to become AYMT, by increasing the size of the minisetts to about 80–100 g, combined with a chemical treatment to protect from pests and diseases and planting directly in the field, bypassing pre-planting in nurseries (Table 4.1; McNamara 2012). Because of the simplicity,
cost-effectiveness (labor savings), and high germination rate, AYMT was well appreciated by the farmers and is fast emerging as the choice technique for seed yam production in West Africa.
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Table 4.1. Features of the different yam seed production methods
YMT AYMT Partial sectioning Traditional methods
Designed by NRCRI/IITA NRI/IITA/DDS NRCRI Farmers
Sett weight About 25 g 80–120 g Whole tuber partially
sectioned Whole tuber of
about 200–500 g**
Chemical Pesticide & wood
ash Insecticide &
fungicide Not treated Wood ash
Application Dust Water-based dip - Dust
Mode of
planting Nursery for
pre-sprouting Directly in the field Whole in fertile soil or
compost Directly in the field Multiplication
Source: Coyne et al. 2010; Kenyon 2006; McNamara et al. 2012; Orkwor and Asadu 1998.
*Depending on the size of source yam.
** The traditional method is based on the use of whole tuber, while YMT and AYMT are setts.
3. Seed users
3.1 S
EED ACQUISITION AND ACCESSIBILITY OF SEED 3.1.1 Before the interventionThe purpose of this project was to identify the best method (practicable and economical) from various seed yam technologies already developed, and to share the technology through demonstrations and other methods among seed producers in Nigeria and across West Africa.
Chikwendu et al. (1995) showed that although 78.8% of farmers in the eastern forest zone of Nigeria were aware of YMT, only 48.8% had actually tried it. Agbaje and Oyegbami (2005) found that only 33% of farmers adopted the technology in southwest Nigeria, despite 60% of the farmers having received information from the agricultural development program in their states. A DFID project final technical report also suggested that the rate of adoption was low (Kenyon 2006).
Farmers may produce seed yams to sell, to plant, or both. Most farmers sell seed yams only after they have enough to plant their own fields. West African farmers customarily make setts as planting material by cutting ware yam of about 1.2 kg into three plantable setts, each weighing about 400 g. It is also common for farmers to treat their setts with wood ash. Traditionally, farmers milk their yams to produce seeds (Philips et al. 2013). It is productive since for every milked tuber the remaining plant will generate five seed yam tubers (Ibana et al. 2012; Ikeorgu and Okonkwo 2010). That this functional practice exists may account for the low adoption of the YMT.
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5 3
Men do most of the work in growing seed yams, which requires substantial energy and time (Oguntade et al. 2010); women are mostly involved in selling the seed yam. Most of the women who produce seed yams hire male laborers.
The baseline survey for this project showed that very few of the farmers were using the YMT. In Ekiti, both milking and cutting setts were used, whereas the farmers in Kogi often bought their planting materials. Most of the Ekiti HH believed that their home-grown planting materials were better than those on the market, whereas the HH in Kogi believed the opposite. Despite this, most farmers in both regions who had participated in the project were enthusiastic about growing more seed yams both for their own use and for sale.
3.1.2 What changed as a result of the intervention
The project developed simple written materials about pests and diseases and also explained step-by-step how to produce clean seed yams. These have become popular with the individuals and groups who received them. Several groups adapted the materials to their own needs and disseminated them.
Figure 4.2 shows the steps of the (older) YMT. The AYMT involves cutting the yams into large pieces (about 80 g), dipping them in insecticide, and then air drying them and planting them directly into the yam mounds in the field the next day. This avoids the labor costs of making the seedbed to pre-sprout the yam. However, YMT required too much labor and had a low establishment rate in the field. On the other hand, AYMT had a lower multiplication ratio of seed than YMT, but was less work (e.g., without the pre-sprouting step) and had a better on-farm establishment rate.
1. Yam is cut into minisetts 2. Minisetts dipped in fungicide and insecticide solution
3. Minisetts planted in seedbed 4. Sprouted minisetts ready to transplant to mounds in field
Figure 4.2. Steps of producing yam minisetts. Stage 3 in the figure is often required for YMT but not for AYMT. Source: Adapted from Otoo et al. 2001.
54 C A S E S T U D I E S O F R O O T S , T U B E R S A N D B A N A N A S S E E D S Y S T E M S
The project has also stimulated stakeholders to lobby the Nigerian Government for a Presidential Initiative to support improved and healthy seed yam production in Nigeria, to safeguard the future of the crop and for food security in Nigeria and West Africa.
Farmers already have simple techniques for producing their own good quality seed yams. But growers regard these as risky and requiring a large cash investment at times of the year when most of them have little money. However, farmers believed that productivity and farm income could be improved if the supply of good quality seed yams could be increased.
The project outputs suggested that there is a potential to grow seed yam commercially in Nigeria.