Cashew cultivation in Nigeria

Cashew (Anacardium occidentale) is an evergreen tropical and frost sensitive tree crop that forms large canopy and can grow to 12 metres high. It grows well in fertile sandy loam soil, requires temperature between 25 - 30 degree celsius and precipitation between 1000 and 2000mm. It is a native of Brazil and was introduced in Nigeria by Portuguese in the 16th century. The tree is mostly valued for the nuts which are mainly harvested once in a year.

Indians and Indonesian importers are the major buyers of the nut in Nigeria. They mostly buy from places where quality cashew nuts are produced in abundant quantities. Reports and observations from cashew nut production and marketing have shown that the bulk of quality cashew  nuts comes from Ogbomoso, Oyo State. The town has suitable soil and weather for cashew nut production.

Cashew varieties
There are three main varieties which are Brazilian cashew, Chinese cashew and Indian cashew. Brazilian cashew is mostly grown in Nigeria.

Land preparation and planting
After clearing of the vegetation, the land must be ploughed and harrowed. The nuts can be sowed 3 -4 per hole or raised in nursery and transplanted in the field. After the establishment the plant are thinned to one healthy and vigorous plant per stand.

Plant spacing
Two spacing methods can be adopted and these are 9m X 9m and 4.5m X 4.5m. The improved varieties start to produce fruits eighteen months after planting. The yield can't be much during the first few years but after 5 years there will be increase in the yields. Cashew can be intercropped with arable crops such as soybean, cowpea, groundnut, melons and vegetables for some years. It is not advisable to to intercrop cashew with corns because the crops can grow taller than the seedlings and cast shadows on them. The crops can also cause significant removal of soil nutrients.

Expected yields can be determined as follows:
At 18 months after planting 1kg per tree is expected, and with the spacing of 4.5m X 4.5m, 132 plant stands will produce average of 132kg per acre. Between 3 and 5 years it will produce average of 15kg per tree and 1980 kg per acre. Between 5 and 10 years it will produce average of 35kg per tree and 4620kg per acre. Above ten years a tree will produce average of 80 kg per plant. The plant population should be reduced to 9m X 9m at the end of 5 year to allow the trees to form big crowns.

Weeding
Manual and chemical weeding can be practiced. Manual weeding can be done at the seedling stage but after full establishment, herbicides can be used in the plantation. Contact herbicide is recommended, but the spray must not touch the leaves.

Flowering
Flowering and fruiting is affected by the weather condition. It takes two months from flowering to ripening of the fruit, and flowering can  continue for three months.

Harvesting
The apple must be harvested and processed immediately because it is highly perishable and gets spoilt within few hours. It can be eaten fresh or processed into juice. The nuts must be well dried in the sun before they are bagged and stored. Well dried nuts can be stored more than a year before they are shelled or sold.

The apple is very rich in nutrients, 3 times greater than orange in vitamin C. Syrup, wine and gin can also be produced from the apple. The nut kernel contains 21% vegetable protein and is as rich as milk, egg and meat in proteins, vitamins and minerals.

Shell oil or fluid is a by product that contains combination of anacardic acid and cardol. It is used in the manufacturing of materials that are resistant to heat, friction and caustic products. It is used in clutch plates, special isolators, varnish and plastic materials.

The bark of cashew tree is rich in tannin being used in leather tannin. Other parts such as leaves, fruits, wood, gum, bark and juice are used for preparation of local medicines.

Measuring quality of Cashew nut
The quality of cashew nut is measured by Kernel Outturn Ratio (KOR) which is the amount of usable kernels after shelling of the nuts. It is measured as the weight of the kernels in Ibs per bag of cashew nuts (80kg or 176 Ibs). A KOR of 48 means there are 48 Ibs (21.8 kg) of usable cashew nut kernels in a bag of 176 Ibs (80kg). KOR ranges between 20 - 24%.

Cashew nut is an export commodity and highly demanded for in the USA, Japan, Australia, Canada and some European and Middle East countries.