Impact of cowpea breeding and storage research in Cameroon - IITA

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Cowpea postharvest and socioeconomic studies The fall of 1994 and 1995 was a period of major extension activity in cowpea storage. SODECOTON sold about 300 heaters in the first few months of 1995. The National Agricultural Extension and Training Project (PNVFA) disseminated the technology to approximately 1500 villages in the Far North Province where it has a regular presence. Programs in French and local languages were aired on local radio. Interviews with key informants in the fall of 1995 indicated that about 5% of farmers were using CRSP technologies, mainly the solar heater (Lowenberg-DeBoer 1995). Triple bagging is not widely used in rural areas because of the lack of bags. The solar heater was used on about 90% of the farms’ cowpea production. Interviews in 1996 and 1997 indicated that the use of the solar heater continued to rise, but that storage insecticide use was growing rapidly (Lowenberg-DeBoer 1996, 1997). These insecticides are readily available at low cost from SODECOTON or from Nigeria border markets. By 1977 it was estimated that 70% of cowpeas stored was treated with insecticides and the use of the CRSP technologies, primarily the solar heater, appeared to have reached a plateau of about 10% of cowpea production. For the impact analysis a logistic function was used to estimate adoption for both the postharvest technologies and varieties. The baseline scenario used a plateau of 10% for postharvest technologies and 13% for varieties. A sensitivity test will be done on a plateau of 25% for both innovations. Prices There is no regular system for reporting cowpea price data in northern Cameroon. Sterns and Bernstein (1993) documented monthly prices for the period 1985–1990. Lowenberg- DeBoer (1995, 1996) obtained some monthly price data for the period 1992–1995. Since September 1997, the Purdue/IRAD project has collected cowpea price and quality data monthly, starting with two markets in the Maroua area and later extending the collection to two additional markets (Langyintuo and Lowenberg-DeBoer 1999). For the model outlined by Diaz-Hermelo and Lowenberg-DeBoer (1999), prices are needed for two periods, harvesttime and after storage. Cowpea harvest typically starts in October. Cowpeas are all hand-harvested by picking pods in the field. Harvesting continues through early December. Many producers store cowpea in pods on a raised storage platform called a danki (Wolfson 1990). Danki storage may last for two to three months. Threshing may occur any time between the beginning of harvest and the following March. For the model it was assumed that newly threshed cowpea might be marketed any time from October to March and the price (P1) was the simple average price from the data for those months. Stored grain was assumed to be stored for six months and sold at the simple average price for the period April to September (P2). Period one and two prices were estimated as the simple average for the periods October to March, and April to September in the available data. Gaps were filled with the average price for the data period, 193 real 1998 FCFA for P1 and 236 real 1998 FCFA for P2. Elasticities For the purpose of the analysis, cowpea supply is the cowpea grain produced in the three northern provinces of Cameroon—Far North, North, and Adamoua. The demand is the sum of local demand for consumption and demand for export outside the northern Cameroon region. For the analysis, cowpea purchased for export in period 1 is treated as 414
Impact of cowpea breeding and storage research in Cameroon consumed; only cowpea stored for local consumption is considered by the storage model. Thus storage by merchants in Maroua awaiting export is treated in this analysis as part of the first period demand. There are no statistics on the proportion of cowpea retained for local consumption in the storage period. Cowpea market studies indicate that a large portion of cowpea production in northern Cameroon is exported and most of the cowpea for export is purchased around harvesttime. The baseline scenario will assume that 80% of cowpea grain is either consumed locally or purchased for export in the first period. That leaves 20% of the cowpea stored, and given estimates (described below) of 52% storage losses prior to the introduction of CRSP technologies, about 10% of the total production is available for local consumption in the second period. A sensitivity test will be done assuming 40% of cowpea is stored. Empirical estimates of the supply and demand for cowpea in northern Cameroon are yet to be made. This analysis used the logic outlined by Masters et al. (1996) to determine elasticity parameters. He states that the typical supply elasticity is in the range of 0.2 to 1.2, and demand in the range of –0.4 to –10. The demand elasticity of –10 would occur when the product is traded in a larger international market. The lower end of the range would be for food crops with only local markets. The cowpea market in northern Cameroon is open to international trade, but Lowenberg- DeBoer (1994) observed that this trade occurred mainly around harvesttime. Later in the year, markets in northern Cameroon were dominated by local demand. This observation explains the high and volatile prices in the April to September period. The baseline scenario in this analysis assumes that the first period has a very elastic demand (–1.0) because of international trade and low elasticity in the second period (–0.40) when local demand dominates. For the supply side, a midrange estimate of 0.7 will be used. Sensitivity tests will be done on both demand and supply elasticities. Storage losses For the baseline model it was assumed that one hole per grain was sufficient to cause a merchant to sort out that grain. While that damaged grain may still have value as livestock feed, this value is much less than that for human consumption. No salvage value for damaged grain was included in the model. The number of holes per grain after a given storage period was estimated using data from on-farm tests of CRSP storage technologies in 1990–92 (Purdue/IRA 1990; Purdue/IRA 1992 supplemental). The on-farm storage tests all ran for about three months. A logistic function of time similar to that used by Schultz was employed (Schultz 1993) to obtain estimates of losses after six months of storage. Unfortunately, no insecticide treatments were used in the on-farm trials; it was assumed that damage levels with insecticide treatment would be similar to that of the solar disinfestations. The initial loss parameter (δ) was estimated as the weighted average loss given the distribution of storage techniques estimated by Wolfson (1990) at the time when the project started. This required lumping techniques into categories for which loss estimates were available. The percentage in each category was ash, 24%; insecticide, 23%; herbs or “nothing”, 48%; hermetic storage, 2%; heating, 2%. Ash loss was estimated by data on the CRSP ash technique (11% after six months), even though the indigenous technique is often less reliable because a lower proportion of ash is used. Because the CRSP trials did 415
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Impact of cowpea breeding and storage research in Cameroon - IITA

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