Farmers’ Perception of the Use and Beneﬁts of Cowpea Storage Methods in Northern Ghana

: Insect infestation during the storage of cowpea is a major challenge among smallholder farmers in sub-Saharan Africa (SSA). Farmers use various postharvest storage methods to deal with insect pests, including insecticides, which may result in health and environmental hazards. Four hundred (400) cowpea farmers were interviewed on their perceptions and preference of different storage methods in Northern Ghana. About 58% of farmers applied insecticides, 50% used ash, and 42% used hermetic triple-layer bags (Purdue Improved Crop Storage, PICS) to store cowpea. Most farmers (85.6%) preferred the PICS technology for its effectiveness (compared to insecticides, ash, and botanicals). Reasons for the non-use of PICS bags included unavailability (39.5%) and high price (11.7%). Farmers perceived that storing cowpea in PICS bags lowered pesticide-related health risks for both farmers and consumers. Thus, there is a need to improve the availability and affordability of PICS bags in Northern Ghana.


Introduction
Globally, over 6.1 million tons of cowpea are produced annually, with about 5.2 million tons produced and consumed in Africa [1][2][3][4]. Ghana is among the topmost cowpea producers in Africa and has over 90% of its annual production coming from its three northern regions (Northern, Upper East, and Upper West regions) [1,[4][5][6][7]. Cowpea farmers in Northern Ghana sell immediately after harvest or store their cowpea to obtain better prices a few months later, mostly during the lean season. However, insect pests are a major challenge during cowpea storage by smallholder farmers. Insect infestation in stored grain is often exacerbated by environmental conditions such as high temperature and relative humidity leading to spoilage and contaminations [8]. Consequently, within the first three (3) months into storage, their unprotected cowpea is rendered unfit for human consumption or cultivation [9,10]. Hence, cowpea farmers need to use safe and effective cowpea preservation methods to maintain the quality of their grains during storage [3].
Across sub-Saharan Africa (SSA), preserving stored cowpea using synthetic insecticides is common among smallholder farmers [11,12]. Insecticides are preferred because they are easy to use and effective [13]. Using synthetic insecticides prevents pest damage but with potentially adverse effects on both consumers and the environment [14]. Often, chemical application for cowpea preservation by farmers results in misuse and overuse due to a lack of proper training [12,15].
However, even before the introduction of synthetic chemicals in Northern Ghana, farmers were using traditional methods for cowpea preservation, including botanicals and inert dust. Botanicals are obtained from a myriad of plants, applied in different forms, leading to variances in effectiveness [11]. Inert materials such as fine sand, ash, or lime are mixed with cowpea grains, hence creating physical barriers to insect movement and reproduction [10,16]. This notwithstanding, the amount of inert material needed for effective protection makes this method less practical for commercial storage of cowpea [9].
In recent years, Purdue Improved Crop Storage (PICS) bags were introduced to cowpea farming communities in several African countries, including Ghana [17,18]. The technology is now widely used to store dry cereal and legume grains across SSA [18][19][20]. The PICS technology has received massive acceptance among farmers in SSA, and its use is being expanded to other regions of the world, including Asia and Latin America [21,22]. Smallholder farmers are more attracted to storing cowpea in PICS bags because they are cost-effective and fit into many of their socio-economic conditions [23]. Other brands of hermetic bags (i.e., SuperGrain bags, Zerofly, etc.) have emerged, but PICS retains the largest share of the market [24][25][26].
Though all these storage methods are available for cowpea storage, there is limited understanding of smallholder farmers' perception of their use and benefits. This study was carried out to investigate the use, perception, and preference of different postharvest storage methods among cowpea farmers in the Northern and Upper West regions of Ghana.

Study Area, Sample Size, and Sampling Technique
This study was conducted in two of the three regions within the Guinea Savannah agro-ecological zone-the Northern and Upper West regions. Based on national statistics, these regions are known to be the major cowpea producing areas in the country [7]. By using a multistage sampling technique, data were collected from 400 cowpea farmers across two randomly selected districts in each of the two regions. In consultation with the Regional Agricultural Development Units and stakeholders involved in the cowpea value chain, districts within each region that actively cultivate cowpea were listed. Two districts were randomly chosen from the list in each region: Tolon and Yendi in the Northern region and Nadowli/Kaleo and Daffiama-Bussie-Issah in the Upper West region. Cowpea growing communities within each district were enlisted with the help of agricultural extension agents. In each district, 10 communities were randomly selected through balloting. In each community, cowpea farmers who stored cowpea and had used different postharvest (PH) storage methods were enlisted, and 10 respondents were randomly selected through balloting. Thus, a total of 400 cowpea producers were interviewed.

Data Collection and Analysis
A pre-test of the questionnaire was performed to assess and revise the data collection tool before the interview of respondents. The research survey was conducted between June and July 2017. Two teams of five trained enumerators (one per region) conducted the interviews. Data were collected through face-to-face interviews using a standardized structured questionnaire with open and closed-ended questions. Information sought included demographics (age, household size, farm size, educational level, and cowpea farming experience), postharvest storage practices, and perception and preferences for the different storage methods.
The socio-economic data were analyzed using standard descriptive and inferential statistical tools. Farmers' preference and perception of the effectiveness of the storage methods were elicited using a four-point Likert scale: 1-most preferred/very effective, 2-preferred/effective, 3-least preferred/somewhat effective, and 4-not preferred/ineffective [27][28][29][30][31][32]. The perception of benefits that farmers associate with the various storage methods was elicited using a Likert scale ranging from 1-strongly disagree to 5-strongly agree [33]. Any mean score between 1 and 1.5 means strongly disagree, and between 1.5 and 2.5 means disagree. Furthermore, a mean average between 2.5 and 3.5 means that respondents are neutral about that statement. Any mean score between 3.5 and 4.5 means that farmers agree with this statement. Any mean between 4.5 and 5 means farmers strongly agree with this statement [34]. Respondents were able to make a meaningful distinction between categories on a 5-point Likert scale due to its shortness [35]. Finally, the average scores were then used to analyze the preferences and perceptions of cowpea farmers in relation to the different storage methods. Simple means were used to interpret the ranking data. The means were determined using the following equation: where, x i = the response (i.e., code on the Likert scale) selected by the ith respondent N = total number of respondents in the study.

Demographic Characteristics and Farm-Level Information of Cowpea Farmers
Demographic and farm-level information of respondents are presented in Table 1. The results show that among the respondents, 66.7% were male, 86.7% were married, 60% did not have formal education, and had an average age of 43.9 years. About 95% of respondents indicated farming as their primary occupation, with an average cowpea farm of 0.8 ha and 14.5 years of cowpea production experience. Most farmers cultivated between 0.4-1.2 hectares during the last cropping season with an average yield of 0.47 t/hectare. A typical household had an average of nine (9) people.

Cowpea Storage Containers Used by Farmers
Farmers stored their cowpea in different kinds of containers/structures such as woven polypropylene (PP) bags, silos, traditional shed/granaries, and other containers (pots, cement bags, drums, storage baskets/basins, jerry cans, etc.) ( Table 2). Most farmers in the Northern region (65.5%) stored their cowpea in woven PP bags, while those in Upper West (43.5%) stored their cowpea in various containers (pots, cement bags, drums, jerry cans, etc.). Overall, the woven PP bag was the predominant storage container used by farmers (41%) in the study area. Mud silos and granaries were used by about a fifth of farmers in the Upper West but almost none in the Northern region. Results showed most farmers (86.5%) stored their cowpea inside the house. It is important to note that sometimes cowpea is kept in pods and stored outside. About a fifth of farmers (21%) in Upper West kept their cowpea in an open space (veranda).

Grain Protection Methods Used by Farmers
Farmers used various cowpea storage methods, including insecticide application (synthetic and botanicals) on grain kept in woven PP bags, PICS hermetic bags, other hermetic containers (such as jerry cans and plastic bottles), and ash (Table 3). About three-fifths of farmers (58%) used synthetic chemical protectants, 50% used ash and 42% used PICS bags to preserve their stored grains. Though readily available, the use of ash was found to be a tedious and laborious task to perform, especially for preserving large quantities of cowpea (Table 3). Among farmers using PICS bags, 85.6% used the technology because of its high effectiveness (Table 3). About two-fifths of farmers used other types of hermetic containers (e.g., jerry cans, plastic bottles, etc.) because they were readily available (Table 3). Major constraints in the use of any storage methods were unavailability of PICS bags (by about 40% of farmers using the technology) and limited knowledge of the use of botanicals (by 44.2% of farmers using this protection method) ( Table 3).

Farmers' Perceived Preference and Effectiveness of Storage Methods
The stated perceived preference for the various preservation methods varied significantly among the users. Farmers using PICS bags had the highest level of preference (90.5%-most preferred), followed by those using ash (78.1%-preferred) (Table 4).
Similarly, PICS scored highest compared to other preservation methods as 90.5% of respondents using the technology stated it was "very effective". As for the perceived preference, ash and synthetic insecticide users came in second and third after PICS bags with 73.1% and 51.1% of respondents, respectively, using these storage methods claimed there were "effective". In order of perceived preference and effectiveness based on collated averages, PICS was ranked the most effective, followed by ash, then synthetic pesticides, then botanicals, and other hermetic containers (Table 4).

Farmers' Perceived Benefits Associated with the Different Storage Protection Methods
Farmers' assessment of PICS bags on all indicators was high, with a score above four out of five suggesting a positive perception of the technology, while both insecticides and traditional methods varied from 1.00 to 3.69 and 2.87 to 3.95, respectively (Table 5). Farmers perceived that PICS bags reduced the risk of chemical poisoning and maintained grain quality (maintain color, no mold, tasty, etc.), and allowed long-term storage. Respondents perceived that all storage methods (PICS, chemical, and traditional) were able to store grains well (free of insect pests) for a long time (Table 5). However, synthetic insecticides were perceived as a source of food poisoning, with the lowest score of one among all indicators and storage methods. Respondents did not perceive synthetic chemicals to influence the taste of stored cowpea.

Demographic Characteristics and Farm-Level Information of Cowpea Farmers
Cowpea is mostly cultivated by male farmers who are married and consider farming as their main occupation. The male dominance in cowpea cultivation on small farms, confirmed by other studies, could be attributed to its high labor input requirements [36][37][38]. Most of these farmers were experienced in cowpea production, which made them more likely to adopt new and improved postharvest (PH) storage methods [38]. Thus, these farmers may have in-depth knowledge and experience of the use and available PH storage methods in their locality. The respondents produced cowpea on small farms because access to land is becoming a challenge, and also cowpea is considered a minor or alternate crop in Northern Ghana [6]. The high illiteracy rate among the farming populace in Ghana, particularly smallholder farmers, has been previously reported [6,15].

Cowpea Storage Containers Used by Farmers
Our survey data revealed that cowpea farmers in Ghana stored grains mainly in woven PP bags and kept these bags in rooms within their houses. Farmers kept woven bags containing grains in rooms due to limited access to warehouses. This is probably because smallholders were storing relatively few bags and had neither the capital nor a pressing need to construct warehouses [39]. Although the use of mud silos was common in the Upper West region (UWR), as previously reported [40], it was non-existent in the Northern region (NR). Storage structures including mud silos and traditional shed/granaries were the second most used storage containers in the UWR. Though we found that a fifth of cowpea farmers in the UWR kept their stocks in an open space (veranda), just about 5% of their peers in NR kept their grains outside. Research has documented variations in storage methods used by smallholder farmers in various countries, including Ghana and Uganda [41,42]. These studies showed that differences in storage types among smallholder farmers were due to their locations (districts where they live), access (cost and availability), and other demographic characteristics such as gender.

Grain Protection Methods Used by Farmers, Level of Preference, and Perceived Effectiveness
The findings of this study show that the majority of cowpea farmers in northern Ghana applied insecticides to their grains before storage. This result agrees with the findings of [37] that most farmers in Ghana store their grains with synthetic chemicals. Many farmers also used ash to protect their stored grains, likely, because of its relative availability at no cost in most households. However, its adoption may be limited because it is tedious and laborious to use for storing large quantities of grains. The use of ash requires a 1:1 proportion volume of ash: cowpea mix for effective preservation; hence ash is typically used for storing seed [9]. About two-fifths of farmers used PICS bags to store cowpea. Similar results were seen in Niger and other countries in West Africa [43,44]. Farmers preferred to use and perceived PICS bags as the most effective PH storage method. This is indicative of the cultural acceptability of bag usage for grain storage and protection, especially since PP bags were also the most predominantly used cowpea storage container. Though PICS bags were preferred by farmers, limited availability was a challenge in rural areas, as seen in other countries in sub-Saharan Africa [24,45].
Other hermetic storage containers such as jerry cans and plastic bottles were used for cowpea preservation in certain households, though they may be used for fetching or storing water. Cowpea farmers perceived these other hermetic containers to be the most ineffective, in spite that these containers were both available and less expensive. This perception of ineffectiveness contradicts what is reported by other studies that hermetic storage methods (e.g., jerrycans) are effective at preserving cowpea [46,47]. Though one-fifths of farmers used botanicals, they had limited knowledge about their usage for storing cowpea. These results are comparable to those obtained by [48], who found that only 20% of farmers used botanicals to store grain. Botanicals were perceived to be cheap, available, and effective. However, many studies have shown botanical pesticides to be less effective compared with synthetic insecticides [49,50].

Perception of the Benefits Farmers Associate with the Different PH Storage Methods
Cowpea farmers perceived that PICS bags had a positive influence on limiting the growth of mold and reducing the dumpiness of stored cowpea. Moreover, cowpea farmers perceived that the use of PICS bags and traditional methods lowered the incidence of food poisoning while the use of chemical storage increased it. Chemicals (e.g., phostoxin, actellic) methods leave residues in cowpea stocks that could lead to food poisoning for consumers. Aside from residues, food poisoning can also result from mold growth [51] vis-à-vis insect infestation [52]. Both toxigenic and non-toxigenic molds produce mycotoxins which cause food poisoning [51,53]. Various studies have shown that hermetic conditions can maintain drier conditions good enough to reduce dumpiness as well as prevent the formation of molds [46]. From this study, PICS bags are perceived to be more effective at hampering both mold and insect infestation and eliminating food poisoning due to chemical use. This shows that if issues of availability and cost are addressed, most farmers would be willing to use storage technologies such as PICS for cowpea storage.

Conclusions
This study was carried out to investigate the use, perception, and preference of different postharvest storage methods among cowpea farmers in northern Ghana. The majority of farmers kept their cowpea grain in woven polypropylene bags and protected the grains from insects using synthetic chemicals, ash, and PICS bags. Aside from effectiveness, farmers were concerned about safety, availability, and affordability when choosing a postharvest storage method. Among the PH storage methods, PICS bags were most preferred, considered safer, and most effective at preserving stored cowpea. However, farmers complained about the unavailability and high cost of PICS bags. Through efforts by the private sector, there is a need to improve the availability and affordability of PICS bags in Northern Ghana.

Institutional Review Board Statement:
The study was conducted according to the guidelines of the Declaration of Helsinki and approved by the Institutional Review Board (or Ethics Committee) of Purdue University (protocol code 1405014885).

Informed Consent Statement:
Informed consent was obtained from all subjects involved in the study.
Data Availability Statement: Raw data are not publicly available, though the data may be made available on request from the corresponding author.