Effect of improved postharvest handling technologies and extension approaches on postharvest losses and quality of maize: case of Kamuli and Apac districts of Uganda

Abstract

Maize farmers in Uganda especially the smallholders experience high quantitative and qualitative losses. In this study, on-farm trials were conducted to evaluate the effectiveness of participatory and farmer to farmer extension approaches in enhancing technology uptake, reducing postharvest losses and improving quality of maize among 108 randomly selected smallholder farmers in Kamuli and Apac districts. Farmer to farmer extension approach involved trained farmers training other farmers on postharvest handling practices while the participatory approach involved researcher-farmer interaction in training and engagement of farmers in on-farm trials. The assessment was done at harvest, drying and storage over six months. The promoted improved technologies were tarpaulins and raised racks at drying, hermetic bags and metallic silos at storage. Grain moisture content, quantitative losses, mold infection and aflatoxin contamination were determined at each of the postharvest stages. Pre-intervention, all the farmers in the study dried their maize on bare ground and stored it in polypropylene bags. Post-intervention, uptake and usage of the promoted improved postharvest technologies was recorded, with higher uptake recorded among the farmers under the participatory approach. In the pre-intervention on farm trials of the promoted and farmer technologies and practices, quantitative losses at harvest were 13.72±5.44%. At drying, losses were significantly higher (p≤0.05) when drying was done on bare ground (3.04±1.50%) than on tarpaulins (1.56±1.09%) and raised racks (0.43±0.58%). Over the storage period, total losses were significantly higher (p≤0.05) in polypropylene bag storage (23.7±5.11%) than in hermetic bags (6.33±5.41%) and metallic silos (0.28±0.22%). Maize dried on and stored in the improved technologies had significantly lower mold infection than that dried on and stored in bare ground and polypropylene bags respectively. The highest aflatoxin levels in maize were recorded at storage with maize stored in polypropylene bags having significantly higher aflatoxin levels (45.82±20.88ppb) than that in hermetic bags (10.36±6.01ppb) and metallic silos (7.55±3.04ppb). Post-intervention, the highest quantitative losses among the farmer to farmer and participatory approach groups were recorded at harvest (13.51±5.04% and 5.16±3.79% respectively) and at storage (12.82±1.48% and 10.08±1.37% respectively). The mean mold infection of maize at all stages from the farmer to farmer approach group was higher than that from the participatory approach group. At harvest and drying, no significant differences in aflatoxin levels were recorded in the maize from the two groups. After six months of storage, the mean aflatoxin level in maize from the farmer to farmer group was significantly higher (20.59±14.9ppb) than that recorded from the participatory group (12.19±9.3ppb). These findings demonstrate that the improved drying and storage technologies in this study can markedly reduce quantitative postharvest losses, and aflatoxin levels in maize to below the EAC standard limits of 10ppb among small holder farmers. Furthermore, postharvest technology uptake and use is influenced by extension approach used in promotion with the participatory extension approach resulting in higher uptake and use of improved technologies; and thus, is more effective in reducing postharvest losses than the farmer to farmer approach.