lthough cassava (Manihot esculenta Crantz) is more productive than most other crops when
grown on acid infertile soils, it is also very responsive to better soil fertility and may require high
levels of fertilisation to reach its yield potential. In moderately acid soils, cassava generally does
not respond to the application of lime except as a source of calcium and/or magnesium. High rates
of Iiming often induce zinc deficiency. When grown on infertile soils cassava seldom shows clear
symptoms of nitrogen, phosphorus or potassium deficiencies, but instead produces small and weak
plants while root yields are reduced. Diagnosis of major nutrient deficiencies is best done through
soil or plant tissue analysis.
The paper therefore describes both deficiency (or toxicity) symptoms as well as critical levels or
ranges of each nutrient in soil and in cassava leaves. When grown on light textured and low
organic matter soils, cassava tends to respond mainly to N application; however, due to the relatively
large removal of K in the root harvest, continuous cassava cultivation on the same soil may
lead to K exhaustion, and K will eventually become the most limiting nutrient. Under normal soil
conditions cassava roots become readily infected with mycorrhizal fungi, which help the plant
absorb P even at low external P concentrations in soil solution. Thus, in most cassava soils in Asia
the crop does not respond much to P application.