Increasing production and reducing postharvest losses of onion in Nigeria
Training is the first step in changing production and storage practices
Nigeria loses as much as 50% of its onion harvest due to postharvest losses. Poor postharvest practices occur throughout the onion value chain, especially during transit. Gaps in knowledge on how to properly grade bulbs for marketing and how to manage stored produce accentuate losses. With few good storage facilities available, farmers are forced to sell onion at low prices during glut periods, reducing their income.
Training is key for improving farmers’ postharvest practices. Under the 2SCALE project funded by the Dutch government, staff from the World Vegetable Center (WorldVeg) and partner IFDC visited onion fields and storage facilities in Sokoto and conducted a training-of-trainers workshop for extension workers and farmers from 17-21 May 2018, with the aim of bridging the gaps in good agricultural production and postharvest practices for this important crop.
Onion losses begin with the farmer’s choice of seeds. Onion farmers in Sokoto typically cultivate local landrace varieties, which allows transfer of undesirable traits to successive crops. Fields showed much diversity in the local varieties, with bulbs of different colours, shapes and sizes. Poor irrigation, lack of information on proper fertilizer formulation, and other gaps in farmers’ knowledge reduced onion quality and yield. Poor management practices such as harvesting bulbs at an immature stage (which causes the plant to develop a thick neck prone to disease in storage), neglecting to properly top the plants (cutting too close and injuring the bulb), drying the onions in the open field (exposing the bulbs to sunscald or sunburn), and inadequate storage contributed to major losses. Onions handled in these ways are prone to rot.
The Rudu—the local straw structure used for storage—can store onion up to six months. A Rudu can be constructed for about NGN 16,000 ($44) and can be used for 3 to 4 years. However, up to half of the onions stored in a Rudu will decay or shrivel. One factor contributing to spoilage is that farmers do not grade or sort the onions prior to storage; onions at different stages of maturity and different varieties are stored together. Diseases quickly spread to the entire lot if the Rudu is not carefully monitored and decaying, moldy onions promptly removed. Sprouting and the growth of bacteria occur when temperatures in the Rudu are too high, and when more than three levels of onions are stacked together, preventing sufficient aeration of the bulbs at the base.
Prior to the training, the WorldVeg team assessed production and postharvest management methods in Sokoto, and identified knowledge gaps and missing key linkages in the onion value chain. The team used the information to conduct a five-day intensive training on onion production and postharvest management for extension officers and farmers. More than 25 participants benefitted from the training- of-trainers workshop; they will go forward to train their colleagues and farmers in the region.
The training covered nursery management, transplanting, land preparation, fertilizer dosing and fertilizer application. Participants discussed the inappropriate practices leading to sprouting problems and spread of bacteria, and how good management practices including curing, topping, sorting and grading can help prevent losses.
During their time in Sokoto, the team learned that local women are employed to sort onions. But after the women remove the physically damaged and rotten bulbs from a lot, some will sell the spoiled bulbs in the local market. This is not a hygienic practice and exposes consumers to unhealthy food. Providing alternative income-generating opportunities for women, and raising awareness of the effects of eating rotten onions on human health, may help everyone in Sokoto understand and appreciate the benefits of good-quality onions.
Story and photos: Caleb Ibukun Olanipekun