Cassava is an important crop in terms of food security and income generation in the tropics 1. Although this crop is considered as a staple, this concept has been changing for some countries where cassava is an industrialized and cash crop2. Studies on cassava physiology have demonstrated the potential of this crop of growing under dry, high temperatures and low fertility environments 3–19. Additionally, this crop has a potential to increase its yield under optimum management conditions including fertilizer application and irrigation 20.
While cassava is a relevant crop in Sub-Saharan Africa, the yields in most of the countries of this region are low (<10 t/ha)21. This post will discuss the cassava production system in two countries of this region: Nigeria and Tanzania. This document includes the results of a rapid characterization done as part of the African Cassava Agronomy Initiative (ACAI) project and its comparison with a previous study in the 90s called the Collaborative Study of Cassava in Africa (COSCA) 23.
This country is the first producer of cassava in the World 21. The zones with the highest production of cassava are in the South and North Central regions followed by South East and South West. The yield of cassava was stable since 1990 until 2011 and recently has decreased (Fig1), implying a necessary intervention to modify this trend2.
Cassava represents 70% of the calorie intake of one-third the population of this country 2. This crop is used to produce gari (roasted granule), fufu, akpu flakes, tapioca and starch 2,22. While in 1989 the Collaborative Study of Cassava in Africa (COSCA) registered that at least 80% of the population in Nigeria consumed cassava once per week, a study in 2004 showed that 98% of the population in most of the states eat cassava at least once per week 2,22.
One of the main constraints for marketing cassava in Nigeria is the bad quality of the roads and low maintenance. Additionally, the security check along the roads and asking for money increase the cost of transport which represents a high percentage of the product price (Fig2) 2 . Although women oversee 70% of the activities of cassava production 2, the rapid characterization showed that only 15% of the households have a head women, this value being close to the 12% registered by COSCA 23. The main income of the farmers is from selling the raw (67.9%) and the processed product (28%). The mean number of family members is 10 which is similar to the mean number of 11 found by COSCA in the 90s.
52% of the farmers interviewed are owners of their land while 28% are owners of less than half or none of the areas grown. These values are difficult to compare with COSCA because it used the concept of holding instead of ownership, where 92% of the fields were held by the farmers 23. Few farmers rely exclusively on the production of cassava, then just 34% of the farmers have more than 80% of the cropped area with just cassava.
About 52% of the farmers grow cassava just as an intercropping system while just 23% of the farmers grow cassava exclusively as monocrop. The remaining part of farmers grow cassava both as monocrop and intercrop (25%). The most important food crops for the farmers are cassava, maize, and yam while the most important cash crops are cassava, maize, and plantains (Fig3 a and c). The main crop used as an intercrop with cassava is maize followed by yam and bambara groundnut (Fig4).
The main planting months for cassava in Nigeria are defined by the rainy season between March and June with a peak in April (Fig5). The range of planting months according with COSCA in the 90s was wider, starting in February and ending by October-November. Cassava is harvested through the year in Nigeria with a peak between April and June (Fig6). Usually, the farmers do not harvest their field at once and prefer staggered harvesting (91%-95%). Just 6%-12% of the farmers use most or all the cassava harvested for own consumption. Most of the farmers use cassava for both own consumption and commercialization (85%-92%). Between 43% to 46% of the growers selling cassava process this crop at home and then sell the derived product, 26%-31% sell cassava in the market, 19%-24% sell the cassava on the farm gate and just 3% to 4% sell the cassava to the processing plant.
Most of the farmers create ridges (37%-61%) or mounds (24%-44%) for the establishment of cassava. The source of the planting material is mainly from the own field (42%-62%) or a gift (15%-22%); however, a low percentage (15%-20%) of the planting material used by the farmers has been acquired from government and research institutions.
In terms of fertilizer application for cassava in Nigeria, 34% of the farmers under monocropping system and 41% under intercropping apply NPK fertilizers to their fields. This value is higher than COSCA, which was 23% of farmers applying inorganic fertilizer (nutrients not specified). For weed management, Nigeria farmers prefer to use herbicides and manual control by hoe (72%-82%). Most of the farmers in Nigeria (68%-79%) consider that they do not register any disease. Just 20% of the farmers have light to moderate disease incidence and less than 8% consider that their fields have a severe incidence of diseases. In that sense, just 2% of the farmers are currently controlling diseases. Those results are contradictory and could need some revision when they are compared with COSCA where the incidence of diseases as CMD and CBB were 86% and 89%.
According to FAOSTAT, Tanzania is the 13th biggest producer of cassava (Fig1). 84% of the production is used for food. While in Nigeria the most important products are the roots, in Tanzania 62%-81% of the farmers also harvest the leaves. The main areas of production are Mwanza, Mtwara, Zanzibar, Lindi, Tanga Ruvuma, Mara Kigoma and Shinyanga. COSCA registered the incidence of cassava brown streak virus (CBSd) and cassava mosaic disease (CMD) as major constraint to the production, along with pests such as green mites and cassava mealybug 24. Contrasting with the miscellaneous uses of cassava in Nigeria, more than 90% of the cassava area reports as most important cassava product the chips and flour. Additionally, the leaves are boiled or sun-dried as vegetable24.
According to the rapid characterization study, Tanzania registered a similar percentage of women as head of the household (13.7%) as Nigeria. The main income of the farmers is from selling the raw product (77.7%) with only 4.3% of the income coming from processed products. Mean number of family members in Tanzania is 7 . 67% of the farmers interviewed are owners of the land while just 16% are owners of less than half or none of the areas grown. Similar to Nigeria, few farmers in Tanzania grow mainly cassava: 29 % of the farmers have more than 80% of the cropped area just with cassava.
In contrast to Nigeria, Tanzania presents two planting periods: the main between September and December and the second between March and May (Fig5). The peak season for harvesting cassava is between June and August (Fig6). Usually, the farmers do not harvest their field at once and prefer staggered harvesting (79%-83%).
Contrary to Nigeria, 47% to 51% of the farmers in Tanzania use most or all the cassava harvested for their own consumption. 46% to 50% of the farmers use cassava for both own consumption and commercialization and just 2% to 3% sell all their crop. About 35% to 54% of the growers selling cassava prefer to do it at the farm gate, 30% sell a processed product, 14%-33% sell cassava in the market, and just 0.4% to 2.4% sell the cassava to the processing plant.
The farmers in Tanzania prefers to use ridges (41%-61%) or keep the field flat (28%-57%) previous to cassava planting. The source of the planting material is mainly from the own field (35%-40%) or a gift (28%-33%). According to the rapid characterization, the farmers in Tanzania do not receive planting material from the government or research institutions. When the crop is sowed as part of an intercropping system, the farmers prefer to do the planting vertically (61%) while if it is as monocrop, it can be planted slanted (54%) or vertically (39%).
Most farmers do not apply any fertilizer even under the intercropping system (98%). For weed control, most farmers under the intercropping system (97%) prefer the use of both herbicides and manual control by hoe while under the monocropping system manual control is prevalent (99%). Farmers in Tanzania have a higher incidence of diseases than Nigeria. Between 26% and 31% of the farmers don’t have problems with diseases while 55% have light to moderate incidence of diseases. Just 12% of the farmers have a severe incidence of diseases. The percentage of farmers doing disease control is 31%-43% which is less than the percentage of farmers registering any disease incidence.
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