In the pH range of above 6, Potassium is readily available.
Maintain pH by addition of lime/dolomite
Improve the soil fertility by adding organic matter and wood ash.
For determining the severity of the deficiency, soil analysis is to be done
Use Muriate of Potash (MOP) according to the results of the soil test. Split application is preferable.
Apply foliar sprays of sulphate of potash (SOP) (10 g/litre of water) and wetting agents in the morning as an immediate remedy.
Calcium (Ca)
Symptoms
Symptoms normally appear first on upper leaves, but later spreads over the whole plant.
Leaf deformation such as curling,distortion are observed
Necrotic spots or lesion appear particularly on edges or tips
These spots may enlarge & become brown/black
Overall stunted growth with shorten stems & smaller leaves
Shallow & underdeveloped root system
Brittle stems prone to breakage
Management
Analysis of pH in the soil
Check the pH of the soil. If the soil is extremely acidic (pH between 3.5 and 4.5), apply lime (3.4 kg/cent in two split doses). And in areas of moderate acidity (pH between 5.5 and 6), apply lime 1 kg/cent.
High phosphorus levels lead to calcium deficiency
In alkaline soil application of Gypsum is preferable
Boron is needed for calcium utilization.
So a boron deficiency can also lead to calcium deficiency.
Magnesium (Mg)
Symptoms
Interveinal chlorosis
Yellowing strats from older leaves & progresses towards younger leaves while veins remains green
Leaf curling or cupping inwards are noticed.
Overall plant growth will be stunted
Reduced yield
Deficiency more frequent in sandy soils
At extreme deficiency the leaves become necrotic and develop whitish colour.
Management
Do the soil analysis and confirm the deficiency.
Addition of Magnesium sulphate (32 kg/ acre) in bands near plants.
Long-term usage of dolomite will reduce magnesium deficiency
Magnesium and potassium fertilizers should not be applied together
Sulphur(S)
Symptoms
First appear in the upper and younger leaves.
Deficient plants exhibit yelowing from younger leaves to older leaves
Stunted growth with reduced shoot & root growth
Delayed maturation
Stems become thinner & weaker
Reduced tuber yield
Management
Application of sulphur-containing fertilisers, such as Factamfos, Ammonium sulphate, Single superphosphate, etc., reduces the deficiency.
In sulphur deficient soils, apply sulphur dust (10 kilogrammes per acre).
Deficiency in alkaline soil can be reduced by application of gypsum
Addition of organic material improves sulphur availability in the soil .
Burning of organic waste leads to sulphur deficiency
Boron (B)
Symptoms
Distorted leaves with irregular growth & abnormal leaf margins
Veins of leaves may turn brown/black due to cell death
Yellowing starts from tips & margins whch progress towards leaf suface
Stems become weak & brittle
Reduced root growth
Smaller & deformed leaves developed with short petioles and gummy lesions on the petioles.
Brown gummy lesions on the petioles at the leaf tip and on growing portion of stems are noticed due to boron deficiency
Management
Analysis of soil to confirm the deficiency.
Application of borax (4 kg/ acre) into the soil
Addition of borax (1 gram / litre of water) as foliar spray.
Avoid the combined application of Boron and calcium.
Iron (Fe)
Symptoms
Deficient plants exhibits interveinal chlorosis including veins will become chlorotic.
Green veins become prominent in between the yellowish interveinal areas,
White or yellowish new leaves are formed due to deficiency
Reduced leaf size
Wilting of leaves
Delayed maturation
Stunted growth
Management
Iron content in Kerala soils is often high. So, get a soil test to determine the reason for the problem
Low potassium levels leads to iron deficiency
Addition of Ferrous Sulphate (60 gram/plant or 6 kg/ acre) into the deficient soils.
Manganese (Mn)
Symptoms
Interveinal chlorosis noticed on leaves in the middle portion of the tapioca plant
Brown/black necrotic spots appears on leaves starting from veins
Symptoms will not be seen on youngest leaves
Leaves will become completely chlorotic.
Stunted growth & smaller size of plant
Edge of leaves become dry & withered
Reduced tuber formation
Management
Soil Analysis
Application of Manganese Sulphate (5 gram per litre of water) as foliar spray
Zinc (Zn)
Symptoms
Interveinal chlorosis at younger leaves
Delayed maturity
Tips of leaves become necrotic
Lobes of leaves become narrow, chlorotic and will curl upward.
Deformed leaves with shortened internodes
Management
The optimal pH range for zinc availability is 5 to 7.5.
Confirm deficiencies by doing soil testing.
Apply zinc sulphate to deficient soils (8 kg/ acre)
Avoid the application of Zinc and phosphate fertilizers at the same time
In severe cases, foliar spraying of Zinc sulphate (2 gram/litre of water) with Calcium carbonate (2.5 gram/litre of water) can be advocated in morning hours.
