Soil and Plant Nutrition
Disadvantages: Fertilizer application methods
• Over application usually results in economic
and environmental losses. Broadcasting: fertilizer is distributed manually
• Over supply makes plant tissues soft and vul- over the cropped field.
nerable to diseases and pathogens. • The most common fertilizer application
• Increased rate of soil organic matter decompo- method.
sition resulting in soil degradation. • Highly inefficient method
• Many nutrients applied are easily lost through • High economic and nutrient losses
different chemical reactions.
Organic fertilizers
Advantages:
• Balanced nutrient supply.
• Enhance the soil biological activity.
• Help in improving soil structure.
• Increase the organic matter content.
• Slow release of nutrients makes soil on the long
run fertile.
• Help in combating plant diseases.
Broadcasting
Disadvantages
• Low nutrient content. Placement: application in band or packets near
• Only effective in the long run. the plants.
• It may not supply all the nutrients required for • Two sub-types:
plant growth. i. Band application
• High cost. ii. Spot Application
• Bulkiness. • The fertilizer use efficiency is high.
Efficient fertilizer use • Labour intensive.
Good knowledge and management practices can • Efficient method but with high labour input.
improve the fertilizer use efficiency.
• Select the crops and varieties that suit the local-
ity and have best fertilizer response.
• Select right kind of fertilizer according to crop
and soil.
• The fertilization should be planned for the
cropping pattern and not for single crops.
• Fertilization application rate should be decided
only after discussing your soil analysis report
with your local extension officer or Desai-
Trainer.
• Balanced fertilization should be practiced.
• Crops should only be sown at the locally rec-
ommended periods.
• Maintain optimum plant population and prop-
er plant spacing.
• Effective control of pests and diseases will help
in maximizing the fertilizer efficiency.
• To maximize the yield increase through ferti-
Placement
lizer, all other growth critical factors must also
be optimum e.g. crop must be irrigated at criti-
cal growth stages.
Farmer’s Handbook on Basic Agriculture 47
Soil and Plant Nutrition
Ring application: Spread the fertilizer around • Use slow release nitrogen for plantation crops
the tree at a distance of about one meter. and long duration crops.
• Under puddle condition, use coated urea-neem
oil. Coal tar sulphur coating will make urea to
release nitrogen slow to match the uptake pat-
tern.
• Urea can be cured with soil (1 part urea with
5-10 parts soil) to reduce the losses.
• Phosphate should be placed 4 to 6 cm below
and 4 to 6 cm away from the seeds to ensure
maximum availability.
Ring Application
• Phosphatic fertilizers give better response when
placed in bands near the plant rows.
• Potassic fertilizers can be applied in one dose
Foliar application: liquid fertilizers are sprayed as basal application but for long duration crops
on the crops. the fertilizer application may be done in 2 to 3
splits.
Fertilizer calculations
Here is an example for the application of fertilizers
based on the soil test recommendations. Suppose
the recommendations are 120 kg N, 60 Kg P and 40
Kg K per ha. Calculate the quantity of urea, super-
phosphate and muriate of potash fertilizers needed
to supply the recommended doses!
Foliar Application
Urea content is 46%, so to supply 46 kg N/ha
100 kg urea is required. To supply 120 kg N/ha
• Highly efficient
100/46*120=260.9 or 261 kg urea is required. Simi-
• Special equipment required
larly super phosphate content is 16% P2O5 and the
• High cost
recommendation is given in the form of Phospho-
• Only selected fertilizers can be applied
rous.
Fertigation along with irrigation • % P = %P2O5 X 0.44
• Kg P = kg P2O5 X 0.44
• Kg P = 16 X 0.44
• Kg P = 7.04
So super phosphate contains 7.04 P and the recom-
mendation is given as 60 kg P.
To supply 60 kg P=100/7.04*60=852.27 or 852 kg
single super phosphate is required. Similarly, we
Fertigation
have to calculate the dose of potash through Muri-
Method of application and nutrients ate of Potash (MOP) as MOP contains 60% K2O.
The method of application should be chosen ac- So MOP contains 49.8 K and the recommendation
cording to the nutrient, crop, soil and cultivation given is 40 kg K/ha.
method.
To supply 40 kg K=100/49.8*40=80.3 kg or 80 kg
• Nitrogen application should be applied in splits MOP is required. So based on fertilizer analysis and
and slow release mode to minimize loss. soil test information the fertilizer application rates
• Frequent application in small quantity through are calculated as above.
foliar application is most efficient and results in
quick recovery of crops.
48 Farmer’s Handbook on Basic Agriculture
