Development and Evaluation of an Integrated Grain Drying and Storage System for Developing Countries
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Date
2024-03
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Abstract
Nutrient- and quality-preserving storage of staple grain crops from one harvest to the next is a necessity to promote global food security, but safe long-term storage is a significant challenge in many developing countries (1). Sub-Saharan Africa experiences the highest rates of post-harvest losses (PHL), where crops are lost to microbial degradation or pest infestation before they can be used (1). The region also has several countries with the highest rates of population growth, meaning there is urgent need to reduce loss and waste across the food system (2). Mitigation strategies to prevent PHL are well known. Adequately drying grain to low moisture contents reduces microbial degradation and harmful mold growth during storage, but traditional drying practices of laying out grain to dry in the sun leaves grain vulnerable to weather, pests, dust, and theft and may not dry grain to safe levels (1,2). Meanwhile, hermetic (air-tight) storage techniques reduce damage from storage pests without the use of harmful chemicals, though many currently available technologies are soft-sided and vulnerable to puncture by pests (3). While some technologies have been developed using either mechanized drying or hermetic storage, no technologies have simultaneously addressed drying and air-tight storage. This research developed a new technology considering the principles of appropriate design for small farmers in developing countries: affordability, ease of use, and context-appropriate material and energy utilization. A novel integrated grain drying and storage system (iGDSS) was designed and evaluated for its technical feasibility, economic viability, and end-user desirability.
The iGDSS was first technically evaluated through experimental trials of heated and unheated drying of maize, followed by 6-month storage trials. Key grain quality parameters were evaluated during storage under pest pressure. The storage trials also evaluated impacts of repeated access to grain – simulating actual practices of subsistence farmers – compared to longer hermetic periods of 3 and 6 months that are typically studied (3). Drying trials demonstrated the iGDSS dries grain evenly, and unheated low-energy drying is completed in under 3 days, saving time compared to current sun-only drying methods. The results from storage trials showed iGDSS maintained grain quality and minimized the growth of harmful storage fungi. The monitoring of oxygen intrusion and pest mortality in a hermetic storage system with periodic access addressed a critical knowledge gap in chemical-free hermetic storage studies. Additional modeling work extended the evaluation of the iGDSS drying functions beyond maize and found estimated drying times of under 2 days for wheat and sorghum, indicating wide usability of iGDSS and improvement over sun-drying methods.
Social and economic assessments of the iGDSS system included field work in the Arusha region of Tanzania, conducting surveys with nearly 300 subsistence maize farmers and focus group discussions in 6 communities to evaluate current post-harvest practices, storage losses, and labor rates. Additional in-country investigations included pricing of system components and construction. Focus group discussions and farmer-reported attitudes on current practices and technologies revealed that even among subsistence maize farmers in one region, there may be different acceptance levels of the iGDSS that can be traced to key variables such as farm size, off-farm income, and education level.
Finally, an ongoing techno-economic assessment of different scenarios identified the most suitable energy sources and farm sizes for the adoption of this technology. The TEA integrates data from iGDSS technical performance, seasonal price changes for maize, and grid and renewable energy availability for Arusha and Kilimanjaro regions of Tanzania.
This low-cost and effective grain drying and storage infrastructure has the potential to greatly reduce post-harvest losses of staple grain crops in developing countries and lead to greater global food security. Future research should utilize the results of the techno-economic analysis develop trainings and scaling pathways to disseminate technology production and adoption in the most suitable areas. In addition, the appropriate technology of iGDSS should be further adapted for drying of high-valued crops and seeds.
Description
Food, Agricultural, and Environmental Sciences (FAES): 1st Place (The Ohio State
University Edward F. Hayes Advanced Research Forum)
Keywords
grain drying, hermetic storage, appropriate technology