Cassava

Manihot esculenta / Mufarinya (Sh) / Ikhasava (N)

Cassava plays a particularly important role in agriculture in developing countries, because it does well in poor soils and with low rainfall (400-500 mm). Its wide harvesting window allows it to act as a famine reserve, field stored for many months, is invaluable in managing labour schedules, and means harvesting can be delayed until market or processing conditions are more favourable. Cassava is, therefore, highly acceptable in rural areas.

While cassava has had a long history in the rest of Africa, it is not a well-known crop in Zimbabwe.

BIZ, in collaboration with Brightface Enterprises (Pvt) Ltd, has been trial-producing 2 cassava varieties with farmers in Chipinge since 2013. Beginning of 2015, 8 other promising varieties, sourced from Chiredzi Research Station, were planted in a demonstration plot. Growth, diseases, responses to different fertiliser applications and yields of tubers are being monitored.

Overview

Where it does well: Cassava originated in South America and was introduced to Africa in the 16^th century. It is now mostly grown in West Africa and the adjoining Congo basin, tropical South America and Southeast Asia. Generally, the crop requires a warm humid climate that is frost-free all year round. Maximum yields can be obtained where rainfall is fairly abundant. It can however withstand prolonged drought periods thus making it valuable in regions where annual rainfall is low or where seasonal distribution is irregular.

Planting – harvesting time – What is harvested?:

Cassava is propagated by stem cuttings and planted during the warmer, rainy season months.

Cassava is primarily grown for its roots but all of the plant can be used. The roots are hand-harvested. The upper parts of the stems with the leaves are cut off before harvesting the roots.

The plant requires at least 10 months when irrigated to produce a crop. However, when it is grown under rain fed conditions, it takes at least 15 months before harvest.

Average yield per ha: Cassava yields can be quite high, as high as 20 to 35 tonnes/ha, but typical yields are 10-15 tonnes/ha.

Properties

Cassava root is essentially a carbohydrate source. Its composition shows 60-65% moisture, 20-31% carbohydrate, 1-2% crude protein and a comparatively low content of vitamins and minerals.
Cassava leaves are a fairly good source of protein and rich in lysine.

Use

Cassava is used in both human and animal food, in many industrial sectors, particularly in the form of starch, and more recently to produce ethanol.

Cassava leaves and roots must be cooked properly to detoxify before they are eaten. Cassava leaves can be eaten as a fresh vegetable, or dried and ground.The roots are cooked, steamed, fried or roasted. The root can also be made into a flour.

Dried cassava in the form of meal, chips and pellets is an important animal feed ingredient.

Cassava is very versatile and its derivatives and starch are applicable in many types of products such as confectionery, sweeteners, glues, plywood, textiles, paper, biodegradable products, monosodium glutamate, and pharmaceuticals.

Whilst cassava is still a small player on the biofuel arena, its role should increase. With 1 tonne of cassava, around 280 litres can be produced of 96.6% v/v ethanol.

Markets

The bulk of world trade in cassava is in the form of pellets and chips for feed, and the balance mostly in flour and starch for food processing and industrial use. Especially the markets for cassava starch are growing. The Asian continent is the biggest importer of cassava.

In Zimbabwe, cassava leaves, roots and flour are traded informally at a very small scale, primarily to communities of Malawians and Mozambicans, but is not usually for sale in markets. Part of the first roots Chipinge farmers harvest will be sold, fresh, to a local private company looking at producing cassava crisps.

Cassava’s most likely use in Zimbabwe is for the manufacture of stock feed though. Farmers peel, chip, dry and mill the roots into flour. Two local stock feed companies are busy exploring replacing part of the (more expensive) grain carbohydrates in stock feed with cassava flour.