CARDI/CFC/EU PROJECT
Increased Production of Root and Tuber Crops
through the use of Improved
Marketing and Production Technologies
Reference Materials
MODULE 3
RIO CLARO
CASSAVA NUTRIENT REQUIREMENTS
GENERAL ASPECTS
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TOLERATES ACID, INFERTILE SOILS
WHEN GROWN ON SLOPING LAND, EROSION CAN DEPLETE THE SOILS OF
NUTRIENTS AND TOP SOIL
NEED TO IMPROVE SOIL CONSERVATION PRACTICES AND NUTRIENT
APPLICATIONS
TO ENHANCE SOIL CHEMICAL AND PHYSICAL CHARACTERISTICS, OFFER THE
CURRENT CROP PROPER NUTRITION, AND ENSURE GOOD NUTRIENTS FOR THE
FOLLOWING CROP
DEFINITIONS
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SUFFICIENCY: THERE IS ENOUGH FERTILISER IN THE SOIL FOR THE PLANT TO
GROW AND PRODUCE A GOOD CROP
DEFICIENCY: THERE IS NOT ENOUGH FERTILISER IN THE SOIL FOR THE PLANT
TO GROW AND PRODUCE A GOOD CROP.
CRITICAL LEVEL: THE AMOUNT OF FERTILISER IN THE SOIL AND THE
MINIMUM AMOUNT NEEDED TO BE ADDED TO REACH SUFFICIENCY LEVEL.
THIS DEPENDS UPON THE AMOUNT OF NUTRIENTS REMOVED BY THE CROP.
FERTLISER USE
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NO FERTILIZATION
THE FARMER FERTLISES BUT DOES NOT KNOW HOW MUCH NUTRIENTS THE
SOIL HAS- TOO LITTLE OR TOO MUCH FERTILISER OR THE WRONG TYPE
MAINTENANCE FERTILISER: REPLACE NUTRIENTS REMOVED BY THE CROP
WITHOUT CHANGING THE SOIL NUTRIENT LEVELS
BUILD FERTILISER: USING EXCESS FERTILISER TO BUILD THE NUTRIENT
LEVELS OF THE SOIL FOR ANOTHER CROP: IMPORTANT IN CONTINUOUS
MONOCROPPING SYSTEMS
WHAT IS AN ESSENTIAL ELEMENT?
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THE PLANT CANNOT COMPLETE ITS GROWTH CYCLE WITHOUT IT
THE ROLE THE NUTRIENT PLAYS CANNOT BE REPLACED BY ANOTHER NUTRIENT
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THE NUTRIENT IS DIRECTLY INVOLVED IN THE PLANT’S GROWTH AND
REPRODUCTION
MOST PLANTS NEED THIS NUTRIENT TO SURVIVE
MOBILE AND IMMOBILE NUTRIENTS WITHIN A PLANT AND SOIL
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PLANT: MOBILE NUTRIENTS WITHIN A PLANT: NITROGEN, PHOSPHORUS,
POTASSIUM, MAGNESIUM, MOLYBDNEUM, CHLORIDE.
SOIL: (MOBILE): SULPHATE, NITRATE, CHLORIDE, BORATE.
IMMOBILE NUTRIENTS IN PLANT: BORON, CALCIUM, COPPER, IRON,
MANGANESE, NICKEL, SULPHUR, ZINC.
RELATIVELY IMMOBILE IN SOIL: AMMONIUM, CALCIUM, COPPER, IRON,
MAGNESIUM, MANGANESE, MOLYBDENUM, NICKEL, POTASSIUM, PHOSPHATE,
ZINC.
SOIL FERTILITY
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TEXTURE: CLAY. CLAY HOLDS PLENTY WATER AND NUTRIENTS. SAND: WATER
DRAINS OUT QUICKLY.
ORGANIC MATTER: HAS A HIGH CEC.
pH: THE SOIL’S ACIDITY OR H ion CONCENTRATION.
CATION EXCHANGE CAPACITY: THE ABILITY OF A SOIL TO RETAIN AND SUPPLY
NUTRIENTS TO A CROP.
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THE CEC OF THE SOIL REGULATES
NUTRIENT ABSORPTION
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Negatively charged soil particles
the absorption of mineral
nutrients
Cation exchange occurs on the
surface of the soil particle
Cations (+ ve charged ions) bind to
it is –ve charded
If potassium binds to the soil it
displace calcium from the soil
particle and make it available for
by the root
affect
soil as
can
uptake
THE SOIL pH AFFECTS NUTRIENT RELEASE AND ABSORPTION
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pH affects the growth of plant roots and soil microbes
Root growth favors a pH of 5. 5 to 6. 5
Acidic conditions weathers rock and releases potassium, magnesium, calcium, and
manganese.
The decomposition of organic material lowers soil pH.
Rainfall leaches ions through soil to form alkaline conditions
SOIL TESTS ARE VERY IMPORTANT AND IT HELPS TO DETERMINE THE RECOMMENDED FERTILIZER
SOIL TESTING SERVICES
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UNDERSTANDING
THE SOIL TEST
REPORT
THE INTERPRETATION
OF THE SOIL TEST
REPORT
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EXCELLENT SOIL TYPE: CLAY LOAM.
EXCELLENT ph (6. 50)
HENCE, EXCELLENT Ca, Mg AND EC.
SOIL IS LOW IN NITROGEN AND POTASSIUM.
TO IMPROVE THE SOIL FERTILITY:
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Cassava production can be improved if soil acidity is lowered which can be achieved by
applying limestone
In sandy soils leaching is high and therefore requires frequent liming
Contact your County Extension Office to get a soil test done so that the exact
limestone requirement and the type, rate and timing of fertilizer application will be
known
SOIL FERTILITY IN TRINIDAD SOILS - Ways in which high soil acidity affects crop
productivity directly:
1 . Acidic soils have low calcium content which is essential for plant growth
2. High concentrations of aluminum, iron and manganese may be present in acidic soils that
are toxic to plant growth.
3. In acidic soil bacteria may be unable to rapidly decompose organic matter.
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4. Some herbicides are less effective.
5. Poor soil aeration and restricted permeability may result due to soils not being well
aggregated.
SUMMARY
SOIL
NUTRIENT
STATUS,
NUTRIENT
TYPE, SOIL
TYPE, pH THE
CEC ALL
AFFECT THE
AVAILABILITY
OF NUTRIENTS
TO THE
CASSAVA
PLANT
THE IDEAL SOIL: CLAY LOAMS WITH HIGH ORGANIC MATTER.
THE IDEAL pH : 5. 5
THE CASSAVA PLANT: GROWTH AND DEVELOPMENT: 15-90 DAYS AFTER PLANTING
(DAP)
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THIN AND THICK ROOTS: BEGIN TO GROW AND DEVELOP AND FUNCTION IN
WATER AND NUTRIENT ABSORPTION.
TUBER ROOT: BEGIN 30- 40 DAP
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FARMER - THE FIRST FERTILISATION SHOULD BEGIN 60 DAP (2mth) WHEN THE
FIBROUS AND TUBER ROOTS ARE PRESENT
PLANT SETT NUTRITION
THE GROWTH OF THE PLANT DEPENDS ON THE FOOD STORED IN THE
PLANTING MATERIAL 20 DAYS AFTER PLANTING FOR ITS GROWTH
PHOTOSYNTHESIS BEGINS 25 DAP
UP TO 40 DAP, PLANT STILL DEPENDS ON P. SETT FOR FOOD
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NUTRIENT ABSORPTION IN CASSAVA
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THE MAJOR SINK: 2- 3 MAP- THE TUBEROUS ROOTS
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AT HARVEST:
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TUBERS ACCUMULATED MORE K, THAN N, FOLLOWED BY P, Ca, Mg AND S.
HENCE, CASSAVA REQUIRES A LATE APPLICATION OF POTASSIUM
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STEMS, LEAVES, PETIOLES AND TUBERS ACCUMULATED MORE N, K, Ca, Mg, and
S.
HENCE, CASSAVA REQUIRES AN APPLICATION OF FERTILISER (COMPOUND) 2
MAP (SETTS PROVIDE NUTRITION FOR THE PLANT IN ITS EARLY GROWTH
PHASE
NUTRIENT UPTAKE ON TEST CASSAVA FIELD IN TRINIDAD (SEESAHAI and VINE,
1988. unpubl. data) CULTIVAR: M Mex 59
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HARVEST PERIOD: 1 0 MAP.
SOIL TYPE: PIARCO FINE SAND. LOW NPK status.
FERTILISER APPLICATION: 1 2- 1 2- 1 7 + 2 NPK @ 772 Kg/Ha BANDED AT 1 0 WAP.
NUTRIENTS EXTRACTED AT ph 4. 5:
65 kg N/ha; 28 kg P/ha; 1 25 kg K/ha; 49 kg Ca/ha; 21 kg Mg/ha.
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TUBER YIELD: 22 t/ha.
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DRY MATTER AND NUTRIENT DISTRIBUTION OF 12 MONTH OLD CASSAVA cv. M
MEX- FERTILISED vs UNFERTILISED PLOTS (SEESAHAI & HOLMES, 1991)
SUMMARY OF
FINDINGS
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CASSAVA
EXTRACTS
A LOT OF
NUTRIENTS FROM THE SOIL EVEN THOUGH THE CROP CAN GROW ON SOILS
WITH LOW NUTRIENT LEVELS
M Mex RESPONDS TO FERTILISATION.
THE AMOUNT OF FERTILISER TO APPLY DEPENDS ON THE VARIETY, SOIL
NUTRIENT STATUS, RAINFALL PATTERNS AND LAND SLOPE
HENCE, TO CALCULATE THE AMOUNT OF FERTILISER REQUIRED BY THE CROP,
EACH FARMER MUST HAVE HIS OWN SOIL REPORT.
FERTILISER RECOMMENDATION FOR M Mex PLANTED IN PIARCO FINE SAND SOILS
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PIARCO FINE SANDY CLAYS
 APPLY 1 00 kg/ha UREA AT OR BEFORE PLANTING
 APPLY 672 kg/ha (6 BAGS)1 2: 1 2: 1 7: 2 NPK IN SPLIT APPLICATIONS 2 MAP AND AT
6 MAP + 2 BAGS MURIATE OF POTASH
 EXPECTED YIELD: 24 TO 30 T/HA FRESH ROOTS
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NUTRIENTS EXTRACTED AT ph 4. 5:
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65 kg N/ha; 28 kg P/ha; 1 25 kg K/ha; 49 kg Ca/ha; 21 kg Mg/ha.
RICHMOND CLAY LOAM: Mr. HALON DANN PLOT
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pH: 6. 50
N: 0. 1 1 - 0. 1 2% (Low < 0. 1 0%)
P: 69- 85 ppm
(High < 35 ppm)
K: 8- 40 ppm (Low < 80 ppm)
Ca: 2740- 31 60 ppm (High/Moderate 2 - 4000 ppm)
Mg: 480- 61 0 ppm (High/Moderate 360- 960 ppm)
EC: 1 1 3- 1 68 umhos. (Low V. Good < 1 500umhos)
RECOMMENDATION: 1 00 lbs UREA, 200 lbs TSP; 1 00 lbs MP per acre. THEN 3 MAP top
dress with 200 lbs 1 2: 1 2: 1 7: 2 per acre.
NUTRIENT LOSSES FROM RUN-OFF AND EROSION WHEN GROWN ON SLOPES
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SOIL PARTICLES DETACH
THEMSELVES BY THE
IMPACT
OF RAINDROPS AND MOVE
DOWN
THE SLOPE
WHEN FERTILISERS ARE
BANDED
OF PLACED ALONG THE
PLANT,
MORE THAN 80% CAN BE
LOST
THROUGH RUNOFF
ORGANIC MATTER,
MICRONUTRIENTS ARE
ALSO
LOST
CONTINUOUS CROPPING WILL EVENTUALLY LEAD TO DECREASING YIELDS
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CIAT HYBRID PLOT - NUTRIENT DEFICIENCY SYMPTOMS IN CASSAVA: NITROGEN
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General yellowing of older
(bottom of plant). The rest
plant is often light green.
leaves
of the
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occur in low levels of nitrogen.
Reduces
plant
growth
and root
yields.
Stunting
of plants
often
NITROGEN DEFECIENCY
General yellowing of older
leaves (bottom of plant). The rest of the plant is often light
green.
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NUTRIENT DEFICIENCY SYMPTOMS IN CASSAVA:
PHOSPHORUS
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Leaf tips look burnt, followed by older leaves turning a dark green or
reddish- purple.
Reduced plant growth and yields
Plants often have thin stems, narrow leaves and fewer lobes
NUTRIENT DEFICIENCY SYMPTOMS IN CASSAVA: POTASSIUM
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Older leaves may wilt, look scorched.
chlorosis begins at the base, scorching inward
margins.
Reduction in plant height and vigor; thin,
stems, short petioles and small leaves.
In severe deficiency there may be grooves and
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Interveinal
from leaf
CROOKED
cracks in the
upper stem.
NUTRIENT DEFICIENCY SYMPTOMS IN CASSAVA: CALCIUM
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New leaves (top of plant) are distorted or
irregularly shaped. Causes blossom- end rot.
Poor root formation
NUTRIENT DEFICIENCY SYMPTOMS IN
MAGNESIUM
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CASSAVA:
Plants suffering from Mg deficiency
typical symptoms of interveinal
which begins at the tip or edges of the
advancing towards the centre.
Under severe Mg deficiency conditions,
may have
chlorosis,
leaves
the leaf
margins may
become
necrotic.
NUTRIENT DEFICIENCY SYMPTOMS IN
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CASSAVA: SULPHUR
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Sulphur deficiency is characterized by a uniform chlorosis or yellowing of the leaves.
NUTRIENT DEFICIENCY SYMPTOMS IN CASSAVA: ZINC
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There is interveinal chlorosis of the upper leaves.
Initially, little white or yellow spots or patches
appear between the veins.
As the plant grows, each successively formed leaf is
smaller and more cholorotic with very small and
narrow lobes.
The youngest leaves are very light green to nearly
white and may grow in a typical rosette form.
NUTRIENT DEFICIENCY SYMPTOMS IN CASSAVA: COPPER
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Copper deficiency severely reduce yields. Uniformed chlorosis and deformity of the
young leaves may be observed.
The leaf tips often become necrotic and the leaf edges are either cupped upward or
downward.
Fully expanded leaves tend to be large and suspended on long droopy petioles.
Under very severe conditions stem tips may dieback followed by new growth at base
of plant.
NUTRIENT DEFICIENCY
CASSAVA: IRON
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SYMPTOMS IN
Uniform chlorosis of the
leaves.
The veins remain green
under more severe
the veins including the
turn yellow to almost
Plant height and leaf size
youngest
initially but
conditions
petiole may
white.
are
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reduced.
Entire plant uniformly chlorotic
Can be mistaken for Nitrogen deficiency
NUTRIENT DEFICIENCY SYMPTOMS IN CASSAVA:
MANGANESE
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There is an interveinal chlorosis of young fully expanded
leaves.
Reduction in size of plant parts (leaves, shoots and tubers).
Dead spots or patches.
NUTRIENT DEFICIENCY SYMPTOMS IN
BORON
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CASSAVA:
Boron deficiency mainly affects the
growing
points of tops and roots.
Plants show suppressed development of
lateral
roots and sometimes death of root tips.
There is a marked reduction in plant
height
because of the reduction in internode
length
towards the growing point.
Upper leaves are dark green, small,
deformed and carried on short petioles.
Lower fully expanded leaves develop a
chlorosis of minute grey, brown or
purple
specks concentrated mainly near the
tips
and margins of the leaf lobes.
A distinctive characteristic of boron deficiency is the development of lesions on the
stem and petiole, from which a brown gummy substance exudes, which later develop
into stem cankers.
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CONCLUSION
GOOD FERTILISATION GIVES STRONG HEALTHY PLANTS CAPABLE OF RESISTING
PESTS AND DISEASES
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