Environmental Engineering Reference
In-Depth Information
taBle 13.1
World cassava Production (2008)
area harvested (ha)
Production quantity (t)
Africa
11,988,993
118,049,214
Asia
3,967,563
78,754,445
Americas
2,718,461
35,903,872
Oceania
20,145
242,649
World
18,695,162
232,950,180
Source:
Calculated from FAOSTAT, 2010. Available at http://faostat.fao.org/
site/339/default.aspx (accessed June 19, 2010).
of castor oil, which has also been proven to be a biodegradable and environmentally friendly fuel. The
large-scale production of these economically important Euphorbiaceae plants, including cassava, pres-
ents an opportunity for agricultural development in arid and impoverished areas (Gressel 2008).
13.2 BotanIcal descrIPtIon and cultural PractIces
Cassava is a perennial woody shrub with a plant height that ranges from 2 to 4 m (Fregene et al.
2001). Being monoecious, male and female flowers of cassava are located on the same plant. Male
flowers develop near the tip and the female flowers develop closer to the base of the inflorescence
(Ekanayake et al. 1997). Flowering is controlled by genotype and environmental factors, including
temperature and photoperiod, which in turn influence the breeding potential of cassava. The fruits
are capsular with three locules whereas the seeds have a caruncle, which varies in size (Nassar 2000).
Root yield in cassava is dependent upon the balance between leaf area and root production (Cock
et al. 1979). Root yield also determines starch yield, which is important for ethanol production.
Propagation in cassava is carried out by stem cuttings called “stakes” and by seed, but the use
of stakes is most common. Spacing depends on the variety and the cropping system. Under sole
cropping systems, a 1 × 1 m and 1 × 0.8 m is recommended for the branching types and nonbranch-
ing types, respectively, whereas for intercropping, 1 × 1.5 m and 1 × 1 m is recommended for the
branching and nonbranching types, respectively. Although cassava can be grown in all types of
soils, including infertile and arid lands, the growing demand for cassava in the bioenergy produc-
tion increases the need for farmers to adopt fertilizer use to improve cassava productivity. Under
intensive cultivation, cassava depletes the soil off the nutrients especially potassium (Carsky and
Toukourou 2005). Fertilizer input has been shown to substantially increase yields (Howeler 2008;
Fermont et al. 2010). Exchangeable potassium is known to be especially critical for cassava produc-
tion (Howeler 1985) due to its cultivation by small resource -farmers on low fertility soils. Out of
fourteen cultivars of cassava tested for response to potassium fertilization, CM507-37 found to be
the best genotype that tolerates low potassium soils (EL-Sharkawy and cadavid 2000).
`Loosen-structure soil such as light sandy loams and loamy sands are optimal for cassava root for-
mation (Sriroth et al. 2010). The plant can cause severe erosion when grown on sloppy land because
of the wide spacing and the slow initial development (Suyamto and Howeler 2001). Although it is
grown in a wide range of climates (between 30° north and 30° south latitude), from drought-prone
to well-watered regions, it is commonly cultivated in areas receiving less than 800 mm rainfall per
year with a dry season of 4-6 months and where tolerance to water deficit is an important attribute
(El-Sharkawy 1993). Cassava is naturally tolerant to acidic soils (Jaramillo et al. 2005) but will not
tolerate waterlogging and high pH associated with sodium salts. In general, cassava does not require
irrigation and pesticide application (Nguyen et al. 2008). Weeding is required during the first few
months until cassava plants develop shade large enough to compete for sunlight.
