Pit silos require hermeticity to serve as an alternative low cost storage facility for maize grain by smallholder farmers

Abstract

Improved grain storage is important in reducing postharvest losses and ensuring food security particularly among smallholder farming communities. In this study, a survey was carried out to establish grain storage practices and farmer perceptions among smallholder communities using 60 farmers in Shurugwi District, Zimbabwe. This was followed by a pilot scale study to test the effectiveness of the pit silo as a low-cost storage system for resource-constrained smallholder farmers. Four storage systems (pit silo, hermetic bag, insecticide-treated polypropylene bag and untreated polypropylene bag) were tested at Chinhoyi University farm, Zimbabwe, from December 2017 to May 2018, then for the same period in 2018 to 2019, using a completely randomised design replicated four times. Survey results showed that 96% of the farmers stored their maize grain in unimproved facilities. Most farmers (90%) stored their grain harvests for less than 12 months. Grain that was stored in pit silos contained the highest moisture (12.7-13.8%) while that stored in hermetic and untreated polypropylene bag had the lowest moisture content (8.5-9.7%). Pit silos had higher insect pest infestation than hermetic and insecticide-treated polypropylene bags but had as much as three times fewer insects than untreated polypropylene bags. The highest (30%) and lowest (16%) grain weight losses were recorded under pit silo and hermetic bag storage, respectively. Germination percentage was also least in pit silo and greatest in hermetic bag storage. Pit silo stored grain contained higher concentrations of aflatoxins AFB1 (24.8 ppb) and AFG1 (6.4 ppb) relative to hermetic and untreated bag storage (0-0.8 ppb). The results of this study suggest that whilst pit silos perform better than unimproved systems such as untreated bags, further design work is required for it to match other efficient systems like the hermetic bag.