Post-harvest activities in pigeon pea

Backgrounder

Introduction 

Almost one-quarter (22%) of total pigeon pea production in Mozambique is lost due to lack of effective pre-harvest, harvest, and post-harvest practices. Promoting the adoption of improved pre- and post-harvest practices and practices to control moisture levels can not only increase yields and quality, but also:

• substantially minimize post-harvest losses,
• encourage farmers to increase the size of their farm, and
• generate enough good-quality surplus for processing into value-added food products.

Proven practices for harvesting, threshing, winnowing, transport, and storage operations minimize post-harvest losses. Thus, it is important that extension services, through radio and other means, provide training and demonstrations to farmers on adopting good post-harvest practices.

Why is this subject important to listeners?

This subject is important because it will alert listeners to the importance of recommended ways of harvesting, drying, threshing, and storing pigeon peas that will:

• Advise them on the right times for harvesting in order to maximize yield.
• Ensure good quality pigeon peas from harvest to consumer.
• Support listeners to use various methods of treating stored products, ensuring it remains in a safe, healthy condition.

What are some key facts?

• Farmers lack knowledge of best agronomic/farm management practices to maximize legume and main crop yields, including the use of appropriate fertilizers, pesticides, and seed varieties. This affects pigeon pea yields. Because pigeon peas compete with other crops for limited resources and because of the importance of maize as a food security crop, promoting adoption or expansion of legumes must incorporate capacity-building for farmers on best farm management practices.
• Lack of cash limits farmers’ investments in pigeon pea-specific inputs, as well as post-harvest measures such as storage. This reduces pigeon pea yields due to pest damage during the cropping season, in particular from the flowering stage to storage. Thus, farmers are less likely to profit, discouraging adoption or expansion of pigeon pea acreage.
• Access to markets: Transport infrastructure is poor and buyers do not come to farmers. The resulting poor access to markets limits the potential of pigeon farmers to earn and discourages them from adopting good growing practices and expanding their farms. Increasing production beyond household consumption needs would require better access to markets.

What are the big post-harvest challenges with pigeon pea?

Harvest consists of picking the mature pods by hand. The harvested pods are then threshed on a tarpaulin with sticks, and then the grains are dried and stored. Farmers used various storage containers, including calabash gourds, cans, and sacks to store pigeon pea grains. Crop losses occur before and after harvesting and result from inadequate drying, inadequate storage facilities, and lack of appropriate technologies such as integrated pest management practices during production and post-harvest. The post-harvest challenges in each stage are as follows:

• Most farmers experience post-harvest losses while drying pigeon peas in the field in preparation for storage. The main causes for these losses are insect pests, followed by rodents and birds.
• Moisture content challenges during drying of grain prior to storage: Most farmers reduce moisture through sun drying to acceptable levels before storage, while others dry on the ground or use a mat/tarpaulin.
• The main challenge during grain storage is insect damage, followed by rodent damage, ineffective chemicals, and theft. Some farmers deal with these challenges by adopting conservation and storage technologies and integrated pest management for moisture and pest control, respectively. But most farmers do not adopt them.

Gender aspects of post-harvest pigeon pea activities

• Pigeon pea production and marketing involves all members of the household, including men, women, and children. Family labour remains the major source of labour in pigeon pea cultivation.
• The unequal division of labour within the household and the idea that legumes are a women’s crop results in women providing most of the labour for pigeon pea and other crop production (e.g., maize), as well as for domestic chores. Given this situation, expanding production is likely to add to women’s workload if the existing gender division of labour remains unchanged. Labour and other resources are prioritized for more profitable crops, sometimes resulting in neglect of post-harvest activities for pigeon pea.
• Applying pesticides is a challenge for women farmers since spraying equipment is usually large and difficult for women to operate. As a result, women rely on their husbands or other adult men. For widows and unmarried women, lack of resources limits their ability to hire labour for this activity. The inability to use or hire labour to apply pesticides increases the risk of damage to pigeon peas by insects or other pests.
• Cultural norms view men as household heads, and men are in charge of major farm investment decisions such as what to cultivate, where and how to cultivate, investments in inputs, and the allocation of productive assets such as labour, education, skills, and land. This means that efforts to promote pigeon pea must find ways of improving household decision-making to stimulate or provide incentives for investment in pigeon pea.

Impact of climate change on post-harvest pigeon pea activities

The changing climate and weather conditions have a major impact on rainfed crops. Only a few days’ exposure to high temperatures (30-35ºC) can cause heavy yield losses through pod drop or damage. Pigeon peas are tolerant to low intensity sunlight and thus suitable for intercropping. Most pigeon pea production area is rainfed. Pigeon peas are tolerant of lack of water, but have a critical and persistent need for water during the flowering phase.

• The main physical factors involved in storage conditions include moisture content, relative humidity, and the levels of oxygen and carbon dioxide present in the storage facility. Farmers should focus mostly on managing temperature, moisture content, and relative humidity, factors that can be easily manipulated to create a suitable storage environment for small farmers.
  • Temperature: Insects and fungi multiply in warehouses between 25°C and 34°C for most insects and between 15°C and 30°C for fungi. The risk of damage to products stored at lower or higher temperatures is limited and, consequently, losses are negligible.
  • Moisture content refers to the weight of water inside the grain, as a percentage of the weight of the grain or seed sample. The moisture content of dry grain varies from 6 to 15%, depending on the type of grain, and is a major factor in the increase of fungi or insect pests in warehouses.

Transportation from the field

• After bagging, pigeon pea seeds should be taken to the nearest warehouse to guarantee safe, long-term storage.
• When the moisture content is 12%, pigeon peas are packed and stored. Pigeon pea seed is susceptible to pest attack in the warehouse, which can cause severe damage to the seeds.
• Pigeon peas are typically attacked by weevils, rats, and other pests. The storage place must be clean, dry, and very cool. Pigeon peas are typically sun-dried to 9-11% moisture. The recommended storage temperature is 15-20 °C with 50-60% relative humidity.

Threshing and winnowing

• Threshing is done by hand using sacks and sticks when the grains are dry. It can be done in the field on mats or tarpaulins, using these same materials at home, or on a clean terrace or other suitable place.
• Farmers should dry the crop in the field until the moisture content is low enough for storage.
• Drying the crop help maintain maximum grain quality, achieve a sufficiently low moisture content, minimize infestations of insects and micro-organisms (bacteria and fungi), and prevent germination. It is essential that drying be conducted quickly and properly.

Cleaning, sorting, and grading

• Pigeon pea farmers should conduct a final manual cleaning and check the uniformity of the seeds, comparing them with the original seeds and eliminating non-uniform seeds.
• Bagging is conducted only after pigeon peas have been cleaned. Pigeon peas should be stored in new bags, or at least bags in excellent condition.

Storage (including pest control)

To be effective, warehouse management requires the adoption of an approach that starts in the field and continues through harvest and storage it until consumption. The principles and main activities to be considered in small-scale storage practices include:

• Physical factors affecting the grain or seed in storage.
• Pests and fungi common in warehouses (e.g., insects, rodents, and termites).
• Handling of pigeon peas during pre-storage.
• Integrated pest management.
• Small-scale storage facilities.

The acceptability of pigeon pea for marketing depends on several characteristics, including:

• grain colour,
• grain size,
• appearance of the grain,
• the quality of the product obtained, and
• taste.

To maintain these good quality characteristics, pigeon pea must be well preserved in a covered, dry, ventilated, and properly disinfected storage space.

Also:

• To allow treatment with storage chemicals, it is recommended to thresh the pod, process, and clean the grain first.
• To ensure that the grain is preserved for a long time, it is necessary to clean the warehouses and protect against mice and fungal infections by fumigating with rodenticides, fungicides, and insecticides.
• High levels of loss of stored pigeon pea is mainly due to insect attack and rats.

Marketing

• Grains can be transported on head loads if the homestead is not far from the market, while larger quantities are transported by pick-ups, bicycles, motor bikes, wheelbarrows, and oxen- or donkey carts.
• The major challenges to receiving good sale prices is lack of grading and standards. Prices are usually set by buyers who collect all grades (including varietal mixtures and high levels of foreign materials) and pay the same price for all. Thus, because there is no premium for quality, farmers have no incentive to bring purified grains to market, meaning cleaned, graded, and high quality grains.

When to harvest

• Harvest when 95% of the pods are brownish-yellow. The harvest usually takes place 60-120 days after sowing, depending on the maturity of the plants. Harvest the pods manually when they are dry and store them in mesh bags.
• Uniform maturity of pigeon pea plants and pods is extremely important so that the harvest can be processed under the best conditions, especially when harvesting with self-propelled mechanical harvesters.

How to harvest

• Normally, maturation is not uniform. Delay in harvesting exposes the grain to pest attack and undermines quality. Pigeon pea can also be harvested by removing the whole plants and exposing them to the sun when two-thirds of the pods are dry. Pods that are already dry are harvested and dried in the sun on a clean terrace or other suitable place.
• Do not harvest in the heat of the day, from 11 a.m. to 2 p.m., to prevent the pods from opening, thus wasting the grains. Yield depends on compliance with the appropriate technologies used in either rainfed or irrigated production systems, the varieties used, and the time of the season, and can range from 1.5 tons to 3 tons per hectare.
• Farmers can harvest selectively, starting by picking the oldest and driest pods and waiting for the new ones to mature. This helps prevent pods rotting from dew or unexpected rain. Remove broken, spoiled, and immature seeds after harvest.

Post-harvest management

• Pre-dry the pods in the shade (in a greenhouse if possible).
• Thresh the pods by hand or with a thresher.
• Clean seeds with a fan or manually (depending on the number of seeds).
• If signs of insect damage are detected, it may be advisable to fumigate the harvested seeds with an appropriate insecticide.
• Fumigate seeds to reduce pests and diseases only if there are signs of insect attack. It is important to note that fumigation is not normally advised for long-term storage.
• The quality of the final product (the grains) depends on a good harvest at the right time, and good drying.

Where can I find other resources on this topic?

1. Abdala, A. J., undated. Maneio de colheita e pos-colheita de culture do feijao boer (Cajanus Cajan (L.) Millsp. syn. Cajanus indicus) producao de semente. https://e2a33560-2b9d-4f84-94cb-d2900c3d87c0.filesusr.com/ugd/839035_1b2c549407c347bb88b99ac902c9f956.pdf
2. Ayenan, M.A.T., et al, 2017. Pigeonpea [(Cajanus cajan (L.) Millsp.)] production system, farmers’ preferred traits and implications for variety development and introduction in Benin. Agriculture and Food Security, Vol. 6, 48. https://agricultureandfoodsecurity.biomedcentral.com/articles/10.1186/s40066-017-0129-1
3. Couvinhas, A., et al, 2018. Manual de Produção e Comercialização de Semente. Instituto Internacional de Agricultura Tropical (IITA). https://e2a33560-2b9d-4f84-94cb-d2900c3d87c0.filesusr.com/ugd/839035_0505be5f3a7a4ce793219deb29b750a0.pdf
4. Donça, M., et al, Manual de cultivo de Feijao Boer, 2017. Instituto de Investigação Agrária de Moçambique. https://e2a33560-2b9d-4f84-94cb-d2900c3d87c0.filesusr.com/ugd/839035_2998d899bae6476ca8a82c735fe5a392.pdf
5. Macharia, D, 2021. KCEP-CRAL Pigeon Pea Extension Manual. Kenya Agricultural and Livestock Research Organization, Nairobi, Kenya. https://www.kalro.org/files/kcep/Pigeon-pea-18.6.21.pdf
6. Me-Nsope, N., and Larkins, M., 2015. Gender Analysis of the Pigeon Pea Value Chain: Case Study of Malawi. Center Report Series, No. 5. Global Center for Food Systems Innovation, Michigan State University, East Lansing, Michigan, USA. https://www.fsnnetwork.org/sites/default/files/pbaae647.pdf
7. Njoroge, A.W., Baoua, I., and Baributsa, D. D., 2019. J Postharvest Management Practices of Grains in the Eastern Region of Kenya. Journal of Agricultural Science, Vol. 11, No. 3, p. 33-42. https://pdfs.semanticscholar.org/ce03/2a087050bd754dbcfced103752140d9bcfcc.pdf
8. Taruvinga, C., Mejia, D., and Alvarez, J. S., 2014. Sistemas Apropriados de Armazenamento de Sementes e Cereais para Pequenos Agricultores. FAO. https://www.fao.org/3/i3769o/i3769o.pdf