Cassava is adapted to soils of low fertility though responds well to manures and fertilizers and higher yields can be realized through timely and proper nutrient management practices. Generally, most of the nutrient deficiency symptoms appear when the concentration goes far below the critical level. But some nutrients like N, Mg and K manifest the symptoms at an early stage.

Youngest Fully Expanded Leaf (YFEL) petiole or leaf blade at 3-4 month stage is the best indicator of the nutritional status of the plant

Critical nutrient concentration in the YFEL of cassava at 3-4 month stage

Nutrient	Deficiency	Sufficiency range	Toxicity
N (%)	<4.7	5.1-5.8	-
P (%)	<0.30	0.36-0.50	-
K(%)	<1.0	1.3-2.0	-
Ca (%)	<0.65	0.75-0.85	-
Mg (%)	<0.27	0.29-0.31	-
S (%)	<0.24	0.26-0.30	-
B (%)	<20	30-60	>100
Cu (µg g-1)	<5	6-10	>15
Fe ((µg g-1)	<100	120-140	>200
Mn ((µg g-1)	<45	50-120	>250
Zn ((µg g-1)	<25	30-60	>120