HARVESTING TECHNOLOGY

Harvesting usually consists of a series of operations – digging, lifting, winnowing, stocking and threshing. Depending on the system used, some of these can be combined or eliminated. During harvest, pod loss is more with the Virginia type than the Spanish types. The loss may be due to various reasons such as harvesting after the optimum maturity period, early harvesting, method of harvesting, excess soil moisture, soil moisture deficit, etc. Soil moisture level is very critical during harvesting. At the time of digging, soil moisture is most important both to reduce pod losses due to poor peg strength and in situ sprouting of seed. When the crop reaches its physiological maturity, irrigation should be stopped. At the same time, it should be maintained at the optimum level during the harvest.

Timing of harvest

Groundnut shows indeterminate growth. The flowering occurs over 2–3 months according to the type of variety. Hence, pods of different sizes can be found during harvesting. The time for harvesting can be determined by pulling out and examining the plant at random. At maturity, yellowing of the top leaves and drying and shedding of older leaves are observed. Spanish and Valencia types of groundnut usually mature 110 to 130 days after sowing, while the Virginia types takes 130 to 150 days. Once the pods are mature, they should be harvested without delay. Harvesting at the right time helps to obtain good yields of pods and oil. If they are not harvested at optimum maturity, they are prone to Aspergillus attack; late harvesting also results in sprouting of pods in the field. The nut takes two months to attain full development. A fully mature pod will be difficult to split easily with finger pressure. This stage is achieved when the vine begins to turn yellow and the leaves start shedding. Delay in harvesting may result in substantial loss in yields.

Method of harvest

The bunchy varieties are harvested by hand and the spreading varieties by digging, ploughing or by working with a blade-harrow. Groundnut should be harvested in bright sunshine so that the pods and vines can be dried thoroughly. Prevalence of high humidity during harvesting leads to development of mould in pods.

Special techniques

There are chances of the groundnut pods germinating before harvesting. This can be avoided by providing a foliar application of Prosopis pod extract or 20% neem seed kernel extract. To prepare the extract, 100 kg of powdered Prosopis pods or neem seed kernels are soaked in 200 litres of water and filtered through a muslin cloth. The extract is diluted to 500 litres for spraying in one hectare of groundnut crop. The use of this extract is effective in inducing dormancy up to 11 days.

Yield

Yield varies in different states. It is determined by factors such as rainfall, soil type, management and crop protection practices. The yield is usually higher in the Virginia-runner type than in the Spanish-Valencia type. The yield of an irrigated crop in the summer is more than double that of a kharif crop. Under rain-fed conditions, the average yield of semi-spreading and spreading varieties is 1.2–1.4 tonnes of pods per hectare and that of the bunch type is between 0.8–1 tonne/ hectare.

POST HARVEST MANAGEMENT

Stripping

Stripping is the process of removing groundnut pods from the haulm after lifting, and usually, drying. After harvest, the pods should be immediately stripped off from the plants or after a few days of drying in the sun. Stripping is normally done by hand and is a tedious and time-consuming operation. The pods are usually removed by picking or flailing.

Drying

The pods should be dried in the sun for at least 7–10 days to obtain a safe moisture level. If by chance the pods are stored damp, there are chances of mould development and this may result in aflatoxin contamination.

Packaging and storage

The moisture content of the pods should be less than 10% during storage. Spread husk or sand or wooden boards on the floor of the storage rooms to inhibit moisture contamination. Groundnut pods can be stored for about 6–7 months by using camphor. This is a common farmer's practice: the fully dried groundnut pods are filled in polythene lined gunny bags to a height of 30 cm after which a few pieces (8–10) of camphor are placed in them before filling them further. After the entire bag is filled up, its mouth is tied tightly.

The bags are kept in a moisture-free area. This work has to be completed before the onset of the monsoon. For every 400 kg of groundnut, mix 2 kg of neem leaves. This will act as a repellent for storage pests.

Shelling

Shelling is usually carried out when the moisture content of the pod is less than 10%. Shelling is done by hand or with the use of a pedal-operated groundnut decorticator or hand-operated sheller.

Updated on : Dec 2014