French: Manioc; Spanish: Yuca; Italian: Iucca, mandioca; German: Tapioka, Maniok; Portugese: Mandioca
Annual (1-2 years). Harvested part: roots; in some cases young leaves. Grown in tropical and subtropical climates, generally at beginning or end of rainy season; cuttings 20 cm in length from mature stems are planted vertical, inclined or horizontal, 5-10 cm below soil surface.
Roots harvested 10-12 months after planting (but may range from 6 to 18 months; there is no fixed time of maturity).
Plant density: 8 000-16 000 per ha; often intercropped with rice, maize and grain legumes.
Optimum soil requirements for cassava
Preferably grown on light to medium soils, well-drained, pH 4.5-7.5. The crop is adapted to semi-arid conditions; it needs adequate soil moisture mainly during planting; once sprouted, it can withstand several months of drought; generally, it is not irrigated, but in some areas responds markedly to irrigation.
Cassava is well adapted to very acid soils with high levels of exchangeable Al. For that reason, is it seldom necessary to apply lime. The plant is also well adapted to low levels of available P, but requires fairly high levels of K, especially when grown for many years on the same plot. The crop is susceptible to Zn deficiency and often shows Zn deficiency symptoms at early stages of growth.
pH 4.5-7.5; exchangeable Al < 80 % saturation; available P > 5 ppm; exchangeable Ca > 0.25 me/100 g dry soil; exchangeable K > 0.17 me/100 g dry soil; conductivity < 0.5 mmhos/cm; exchangeable Na < 2.5 % saturation; available Zn > 1 ppm; available Mn > 5 ppm; sulphate-S > 8 ppm.
Plant analysis data
The youngest fully expanded leafblades without petioles (4th-5th leaf from top) at 3-4 months after planting provide the best indicator tissue. Petioles, stems and roots have much lower concentrations of N, P, and K. Adequate K is very important for starch synthesis and translocation and increases the plant's resistance to anthracnose.
Nutrients may be applied either as organic manure, wood ash or mineral fertilizers. Organic manures and rock phosphate are generally incorporated in the whole soil during land preparations; wood ash is incorporated with the soil in the planting hole; while mineral fertilizers are applied in short bands near the planting stake and covered with soil, generally as a basal NPK dressing at planting or at 30 days, with 1 or 2 top dressings of N and/or K2O at 2-4 months after planting, when enough soil moisture is available. Rates depend on soil fertility status and yield levels:
Preferred nutrient forms:
There appears little difference between nitrate or ammonium forms of N. Being adapted to acid soil, cassava can make good use of rock phosphates, but generally responds better to soluble sources of P2O5 such as single or triple superphosphates. K can be applied as chloride or sulphate, but the former is generally cheaper. Wood ash is also a good source of K. Compound fertilizers are most convenient, if available, but they should either be high in N and K2O or should be supplemented by top dressings of urea and KCl. Zn can be applied as Zn sulphate to the soil if pH < 6.0. Foliar sprays of 1 % Zn sulphate can also be applied, or stakes can be dipped for 15 min in 2 % Zn sulphate before planting.
Present fertilizer recommendations:
Thailand - (north east and south-eastern region). 95 kg N, 45 kg P2O5, 95 kg K2O per ha. This can be applied as 300 kg/ha 15-15-15 at planting, followed at 3 months by a side dressing of a further 50 kg N and 50 kg K2O per ha.
India - (Kerala state): 12.5 t f.y.m., 100 kg N, 25 kg P2O5, 100 kg K2O per ha. The f.y.m. is incorporated before planting; half the N and K2O and all the P2O5 are banded near the stake at planting, and the remaining half of the N and K2O is side dressed near the plant at 45-60 days after planting.
Indonesia - (Java and southern Sumatra): 100 kg N, 50 kg P2O5, 100 kg K2O per ha. All the P2O5 and one-third of the N and K2O are applied at planting and two-third of the N and K2O at 3-4 months (after harvesting the intercrop).
Colombia - (Eastern Plains): 500 kg dolomitic lime, 80 kg N, 100 kg P2O5, 100 kg K2O, 20 kg S and 10 kg Zn per ha. The dolomitic lime is applied once every 4-5 years and is broadcast and incorporated before planting. P2O5 can be applied as rock phosphate, also broadcast and incorporated, or as triple superphosphate (TSP), diammonium phosphate (DAP) nitrophosphate or compound fertilizer. An alternative is to apply 200 kg/ha of DAP and 50 kg K2O/ha as KCl at planting followed at 3 months by 45 kg/ha N as urea and 50 kg/ha K2O as KCl, side dressed.
Brazil - (East-central states and Campo Cerrado): 30 kg N, 85 kg P2O5, 60 kg K2O per ha. The fertilizer is applied in the planting furrow at time of planting, but care should be taken that it is not in direct contact with the planting stake.
ASHER, C.J.; EDWARDS, D.G.; HOWELER, R.H.: Nutritional Disorders of Cassava (Manihot eculenta Crantz). Dept. of Agric., Univ. Queensland, St. Lucia, Queensland, Australia (1980)
DE GEUS, J.G.: Cassava. In: Fertilizer Guide for Tropical and Subtropical Farming. Centre d'Etude de l'Azote, Zurich, Switzerland (1967)
HOWELER, R.H.: Mineral Nutrition and Fertilization of Cassava (Manihot esculenta Crantz). Centro Internacional Agric. Tropical (CIAT) 09EC-4 (1981)
HOWELER, R.H.: Cassava. In: PLUCKNETT, D.L.; SPRAGUE, H.B. (eds.): Detecting Mineral Nutrient Deficiencies in Tropical and Temperate Crops. Westview Press,
Inc. Boulder, USA (1989)
THAMPAN, P.K.: Mineral Nutrition and Fertilization. In: Cassava. Kerala Agric. University Press, Mannuthy, Trichur, Kerala, India (1979)
Author: R. Howeler, CIAT Cassava Programme, Regional Office for Asia, Bangkok, Thailand