Profitable chemical-free cowpea storage technology for smallholder farmers in Africa: opportunities and challenges

Cowpea is the most economically and nutritionally important indigenous African grain legume, grown by millions of resource-poor farmers. It is a key cash crop in areas too dry to grow cotton or other export crops. Most of the over 3 million t of cowpea grain produced annually in West and Central Africa is grown on small farms. Storage is often identified as the key challenge for small scale cowpea growers. Many farmers sell cowpea grain at low harvest time prices rather than risk losses by bruchids during storage. Some traditional methods are effective for small quantities (e.g., 10 kg), but are difficult to scale up. Some effective storage chemicals are available, but they are regularly misused by farmers and merchants. The Purdue Improved Cowpea Storage (PICS) Project is addressing these problems through promotion of hermetic storage in triple layer sacks which have an outer layer of woven polypropylene and two liners of 80 μ high-density polyethylene. Village demonstrations with more than 45, 000 PICS sacks have shown the technology to be effective. Good quality affordable sacks have been produced by manufacturers in Nigeria, Burkina Faso and Mali. Over the past three years more than one million sacks have been produced and sold. Despite the success with the outreach activities and the farmer adoption, the challenge remains to develop sustainable sack distribution networks. Issues identified include reluctance of wholesalers to order sacks due to risk associated with a new product, inability of wholesalers to develop effective distribution networks due to difficulties with enforcing contracts, and limited access to capital. The PICS project is exploring new ways to address some of these issues, including using non-traditional distribution systems for PICS sacks such as agro-dealers networks, and adapting distribution systems that have worked for cell phones and other products. Keywords: Cowpea, Bruchids, Hermetic storage, Supply chain, West and Central Afric

Management lessons learned in supply chain development: the experience of PICS bags in West and Central Africa

In order to facilitate the transformation of African agriculture, Africa’s smallholders will require more and better access to input markets that deliver context-specific and well adapted innovations. This article summarizes the management lessons learned in developing supply chains for Purdue Improved Crop Storage (PICS) bags in West and Central Africa. PICS bags are hermetic grain storage bags that are leading a revolution in the post-harvest handling of grain on smallholder farmers in Africa. The bags have been very popular with farmers, but the major challenge has been developing supply chains to make those bags available for purchase at the village level. This article: (1) describes the PICS supply chain in West and Central Africa; (2) identifies constraints (i.e. financial, structural, social) that impede the development of the PICS supply chain; and (3) analyzes strategies used by businesses to expand distribution channels and increase bag sales

Effects of PICS bags on insect pests of sorghum during long-term storage in Burkina Faso

The PICS bags, originally developed for cowpea storage, were evaluated for sorghum (Sorghum bicolor) preservation. Batches of 25 kg of sorghum grain were stored in 50 kg PICS or polypropylene (PP) bags under ambient conditions for 12 months and assessed for the presence of insect pests and their damage, seed viability and, oxygen and carbon dioxide variations. The grain was incubated for 35 days to assess whether any insects would emerge. After six months of storage, oxygen levels decreased in the PICS bags compared to polypropylene bags. After 12 months of storage, only two pests, Rhyzopertha dominica and Sitophilus zeamais were found in the PICS bags. However, in PP bags there were additional pests including Tribolium castaneum and Oryzeaphilus mercator and Xylocoris flavipes. Grain weight loss and damage caused by these insects in the PP bags were significantly higher compared to those stored in PICS bags. Germination rates of sorghum grains stored in PP bags decreased significantly while no changes were observed in grains stored in PICS bags when compared to the initial germination. After the incubation post storage period, there was a resurgence of R. dominica in sorghum grains from PICS bags but the population levels were significantly lower compared to polypropylene bags. PICS bags preserved the quality and viability of stored sorghum grains and protected it from key insect pests. The PICS technology is effective for long-term sorghum storage but the potential resurgence of insects in low-oxygen environment calls for further research

Geranium Oil Nanoemulsion Delivers More Potent and Persistent Fumigant Control of Callosobruchus maculatus in Stored Grain

Plant essential oils offer eco-friendly alternatives to insecticides, though their instability limits effectiveness. This study evaluated the physicochemical stability and fumigant efficacy of geranium (Pelargonium graveolens) oil nanoemulsion (GONE) versus bulk geranium oil (GOB) against Callosobruchus maculatus. Geranium oil nanoemulsions (GONEs) were prepared via spontaneous emulsification using 8% oil and varying surfactant levels. The 10% surfactant formulation produced the most uniform and stable nanoemulsion, with an average droplet size of 91.85 ± 0.02 nm and a low polydispersity index of 0.16 ± 0.02. No significant changes in droplet size were observed after 30 days of storage at room temperature and 9 °C, confirming the formulation’s stability. A fumigant bioassay was conducted using five concentrations (50, 100, 150, 200, and 250 µL/L air) of GOB and GONE over 24, 48, 72, and 96 h. Both forms exhibited concentration- and time-dependent toxicity against C. maculatus. Complete mortality was achieved sooner and at lower doses with GONE (72 h at 150 µL/L air versus 250 µL/L air for GOB; 96 h at 150 µL/L air for GONE versus 200 µL/L air for GOB). Geranium oil nanoemulsion consistently produced lower LC50 and LC90 values, indicating greater potency. It also significantly reduced progeny development. Residual fumigant bioassays at the LC90 level showed that GONE retained efficacy against C. maculatus adults longer than GOB, causing 50% mortality 12 days post-treatment compared to 21% for GOB. Overall, nanoformulation enhanced the potency and persistence of geranium oil, highlighting its promise for protecting stored grains from C. maculatus

Adoption of onfarm hermetic storage for cowpea in West and Central Africa in 2012

This study is based on interviews with 3456 randomly selected cowpea farmers in 322 villages in ten countries in West and Central Africa in 2010 and 2012. It uses descriptive statistics to track the trends in adoption of cowpea storage technology compared to previous studies and Firth logistic regression to identify important factors in adoption. The interviews indicate that regionally about 46% of respondents use some type of hermetic storage for their cowpeas and about 44% of the quantity of cowpea stored on farms is in hermetic containers. Both the percentage of respondents and the percentage of stored quantity fall slightly short of the 50% benchmark hypothesized. The 2010e2012 estimates compare to about 30% of cowpea quantity stored in hermetic containers in 2003e2004. Regionally, the most commonly used hermetic storage container is the triple layer Purdue Improved Cowpea Storage (PICS) bag. In PICS villages, local unavailability is the most common reason for not using the bags. The logit analysis shows that living in a village with PICS activities is the single most important factor explaining adoption of the technology. In six of the nine regressions participation in the demonstrations was also positive and a statistically significant determinant of adoption. For someone living in a PICS village and participating in the activities the combined effect is highly influential. In Niger such an individual would be 27% more likely than a non-participant from a non-PICS village to use PICS bags. In Senegal he or she would be 55% more likely. Some form of exposure to PICS activities or village technicians is key in adoption of the PICS technologies, though it may not be direct contact with a PICS technician. On average additional cash flow due to storage of cowpea in PICS bags is estimated at $26.58/100 kg bag more than sale at harvest