The document discusses nutrient management for rice cultivation in India, emphasizing the crucial role of nitrogen (N), phosphorus (P), and potassium (K) in maximizing crop production. It highlights nitrogen's significance in promoting growth and yield, outlines the appropriate application rates and timings for N, P, and K, and introduces biofertilizers like blue-green algae and azolla as sustainable nutrient sources. Recommendations for integrated nutrient management (INM) include balanced fertilization, correcting micronutrient deficiencies, and employing organic manures to improve soil health and crop yields.

1. Nutrient
management
NA/2022-089
D.Nithin
NA/2022-090
D.Deepthi

2. • An adequate and balanced supply of plant
nutrients is a prerequisite to maximize crop
production.
• The major nutrients required by rice crop are
N,P,K
• Throughout the rice growing areas in India,N
is the most limiting factor .'N' is usually
deficient where rice is grown because the
same conditions of climate which favour rice
production cause a rapid turnover and loss of
'N' from the rice
• The requirement of 'p' is not as high as that of
'N' wide spread 'p' deficiency in rice to the
applied 'p' are observed in the country.

3. • Efficient use of fertilizers
FUE is low in rice crop .40% of applied 'N' and
26% 'p' alone are recovered by rice crop in
India. There is a need to increase the
efficiency of use of applied nutrients by
applying the right form, right quantity at the
right time and by right method.
Nitrogen Functions of N
1. N promotes rapid plant growth
2. improves grain yield
3. grain quality through higher tillering,
4. leaf area development,
5. grain formation, grain filling, and protein synthesis

4. • Nitrogen deficiency in rice hinders the synthesis of
chlorophyll and proteins, thus reducing
photosynthesis and affecting dry matter production
• N is lost through fertilizer as
1. Surface runoff, NH3 volatilization, leaching,
denotification.
2. Soil characteristics, weather conditions and
management practices the extent of losses .
Rate of application
• For Dwarf and semi dwarf varieties optimum 'N'
rates are 80-100kg/ha during kharif,100 -
120kg/ha during rabi.

5. Time of application
It depends on the
• Texture of soil
• Physiological stage of crop
• Other management practices
• Efficiency of applied 'N' is higher at active
tillering stage than at transplanting and reaches
a peak at PI ,Beyond PI ,the NUE decreases.
Therefore, top dressing is suitable at two times.
first split at tillering and second at panicle
initiation
• When more splits are desired, the period
between 3 weeks after tillering until to 2 weeks
beyond PI may be beneficial .

6. Top dressing
• Application of 'N' at planting and to a lesser
extent at tillering, promotes the formation of
tillers resulting in more panicles/unit area.
• Later application increase in panicle weight
can be obtained with top dressing around
panicle initiation stage.
• Application at PI stage increases the length of'
Flag leaf'providing a longer photo synthetically
active leaf area

7. Method of application of N
1. Right method of application
2. Optimization of split application of 'N' in
relation to growth stages
3. Deep placement of N fertilizer in reduced
4. Irrigation water is let in 24 -48 hrs later
Sources of N
• Ammonia containing or NH4 forming (eg.urea)
fertilizers can be used either for pre plant or top
dressing applications.
• NO3 sources have to be considered for top dressing
everthough it's effectiveness is usually somewhat
less compared to pure ammonium N sources .

8. Slow-release nitrogen fertilizers can help rice
crops grow better and reduce the amount of
chemicals used. Some examples of slow-
release nitrogen fertilizers include:
1. Urea-hydroxyapatite nanohybrids
2. These nanohybrids release nitrogen more
slowly than pure urea, and can be used at
a 50% lower concentration of urea to
achieve the same results.
3. Polymer-coated urea (PCU)
4. This fertilizer provides a sustained release
of nitrogen throughout the growth stages
of the rice plant.
Slow release compounds.

9. Leaf Color Chart (LCC) is a tool that
can help determine when to apply
nitrogen to rice. The critical LCC value
depends on the type of rice and soil:
• Low N response cultivars: 3.0
• Other cultivars and hybrids: 4.0
• Sodic soils: 4.0 for varieties and
5.0 for hybrids
• Transplanted rice: 4
• Direct wet seeded rice: 3
N management through LCC

10. Phosphorus recovery of p= 26%
Functions of P
Phosphorus is responsible for the development
of root, ripening, early flowering and
tolerance to specific biotic and abiotic stresses
in rice. Its deficiency will contribute to
maturity delays and rice vulnerability to
diseases increased.
P deficiency symptoms
Abnormal bluish green color of the foliage
Poor tillering
Slow canopy
Slow maturity
Stunted dark green plants with erect leaves
Thin and spindly stems

11. Rates of application
• The application of 60kg p2o5/ha
for red soils and 80kg p2o5/ha for
black soils is adequate.
Time and method of application
• P fertilizers are best applied basally seeding in last
ploughing by broadcasting and incorporating in the
last puddle.
• The recommendation is 2kg DAP /40m2 of nursery.
• P slurry (ssp: puddled soil: water(1:3.5:5)

12. Potassium management
Time of application: recent studies have shown
that top dressing of k at maximum tillering and at
or before panicle initiation increased rice yields
especially in Sandy soils poor in potash holding
capacity.
Functions of k
Potassium (K) is an essential plant
nutrient that improves root growth
and plant vigor, helps prevent
lodging and enhances crop
resistance to pests and diseases.

13. Symptoms of K deficiency in paddy plants
include:
• Stunted dark green plants
• Yellowish brown leaf margins
• Necrotic tips and margins on older
leaves
• Unhealthy or black roots
• Greater lodging
• Higher level of unfilled grains
K deficiency symptoms

14. Zinc-Functions and Deficiency
Zinc
Zinc is an essential micro nutrient for rice. Its
deficiency is associated with soils of high pH.
Unit increase in pH makes Zn1000 times less soluble.
Alkaline soils with high organic matter aggravate Zn
deficiency (If N & P is increased the uptake of zinc is
decreased)
Functions of zinc: -
 Probable connection with production of auxins.
 Activaton of many enzymatic reactions.
 Close involvement in N metabolism.

15. Zn deficiency Symptoms:
 The mid ribs of younger leaves especially
base become chlorotic.
 Appearance of brown blotches and streaks
on the lower leaves followed by stunted
growth .
 The size of leaf blade is reduced but not
leaf sheath
 Uneven growth and delayed maturity in the
field

16. Correction of Zn deficiency:
-
 Soil application @ 40-50 kg ZnSO4/ha. (For normal soils
once in 3 yrs.) (For saline soils once in every yr.)
 By dipping the seedlings in 2% suspension of ZnO is
both cheap and convenient.
 Seed coating is a new development and is at present
being used in limited scale in drilled or direct seeded rice
production.
Varietal tolerant to Zn deficiency IR8, 28, 30 & 34

17. Iron Fe deficiency
 If iron deficiency is noticed spray 0.25% ferrous ammonium
sulphate at 4 to 5 days interval till the leaves turn to normal
growth. Or 10-15kg ferrous ammonium sulphate as basal
application

18. Biofertilizers
 Bio fertilizers are the living organisms capable of
fixing atmospheric nitrogen or making native soil
nutrients available to crops.
 Atmospheric nitrogen is fixed effectively by the
microorganisms either in symbiotic association with
plant system (Rhizobium, Azolla) or in associative
symbiosis (Azospirillum) or in free living system
(Azotobactor, phosphobacterium, blue green algae) or in
micorhizal symbiosis
 Free living organisms: Important amount fixing
atmospheric ‘N’ are BGA, Azolla, Azatobacter &
Rhizospirillum. Among them, BGA and Azolla can
survive only in lowland conditions.

19. Application of biofertilizer
1. Blue green algae:
 Several sps of BGA can fix N. The most
important species are Anabaena and Nostoc.
 The amount of N fixed by BGA ranges
from 15-45 kg N/ha. Standing water of 2.20 cm
in the field is a prerequisite for growth of BGA
at a temperature of 25- 450C and pH of 7-8
with high organic matter in soils.
 Broadcast at 10 kg/ha of powdered blue
green algae flakes 10 days after transplanting.
 Maintain thin film of water. BGA multiplies
well from March to September and can be
used for any rice variety raised during that
period.

20. 2.Azolla:
 Azolla is a water fern which is used as a
biofertilizer for rice. Azolla pinnata is the most
common sps occurring in India.
 Blue green algae (Anabaena azolla) lives
in the dorsal cavity of azollae which fixes ‘N’.
 A thick mat of Azolla supplies 30-40 kg
N/ha. Unlike BGA, it thrives well at low
temperatures. It grows at a temperature of
20-300C and soil PH of 5.5 – 7.0. It grows
better during monsoon season with frequent
rains and cloudiness.
 It is raised as a dual crop and also
applied as green manure.
 For better growth of it, 25-50 kg of
SSP/ha is applied and standing water of 5-10
cm is maintained continuously in the rice
fields.

21.  1. Dipping roots in Azospirillum slurry: Prepare the
slurry with 5 pockets (1000 g/ha of Azospirillum
inoculant) in 40 lit of water and dip the root portion of the
seedling for 15–30 minutes in bacterial suspension and
transplant the seedlings.
 2. Soil application of Azospirillum: Mix 10 pockets
(2000 g/ha of Azospirillum inoculant with 25kg FYM and
25 kg of soil and broadcast the mixture uniformly in the
main field before transplanting

22. INM
Plant nutrients can be supplied from different sources viz.,
organic manures, crop residues, biofertilizers and chemical
fertilizers. For better utilization of resources and to produce
crops with less expenditure, INM is the best approach. In
this, all the possible sources of nutrients are applied based
on economic consideration and the balance required for the
crop is supplemented with chemical fertilizers. Rice crop
residues add 17 kg N/ha. Application of organic matter in
any form reduces loss of N fertilisers and increases FUE.

23. Steps for increasing F.U.E.
 Apply right quantity at night time (i.e. split application) by right
method
 Adopt root zone placement of N fertilizers
 Follow balanced fertilization 80 kg N + 60 kg P2 O5 + 40 kg K2
O/ha (2:1.5:1) is very economical. Moderate response can be had with
a dose of 60-30-30 (2:1:1).
 Integrated/supplementary use of organic manures (including green
manures) and biofertilisers.
 By correcting micronutrient deficiencies (especially zn)
 By maintaining adequate plant population (400-450 panicles/m2)
 By following proper water management practices (continuous
submergence of not more than 2 cm depth)
 By adopting effective weed control and plant protection measures

24. Nutrient Management for
different Systems of rice of
cultivation
 Dry System or Rainfed Upland Rice:
 Most of the uplands are poor in fertility
status. Application of well decomposed farm
yard manure is very essential to increase the
water holding capacity of soil and supply of
nutrients.
 Application of 10 tons of farm yard
manure, 40-60 kg of nitrogen, 30 kg of
phosphorus and 30 kg of potassium per
hectare helps in improving the yield.
 If the soils are acidic in nature a dose of
1.5 t/ha of lime application will improve the
yield of rice.

25. Wet system or low land rice
 Most rainfed lowland farmers do not
apply fertilizers due to the risk involved
in successful crop production.
 Well decomposed farm yard manure
@ 10 t/ha need to be applied two weeks
in advance.
 Application of nitrogen @ 40-60 kg,
phosphorus 20-40 kg and potassium 30
kg/ha meets the requirement of rice
plants

26. S.R.I. Method of Rice
Cultivation
In S.R.I. method, encourage application of organic
manures as it enhances the macro and micronutrients in
the soil in an eco-friendly way.
 Apply well decomposed farm yard manure or
compost @10-12 t/ha before ploughing and incorporate
them uniformly.
 Use different sources of organic manures such as
azolla, pre kharif green manures, crop rotations with
legumes and crop residues, etc. rather than single
source.
 Apply 50 per cent of the recommended nitrogen, 100
per cent of the recommended phosphorous and 75 per
cent of potassium as basal dose before last puddling and
incorporate.
 Apply second dose (25 %) of nitrogen at the time of
second weeding (20 DAT) and final dose of 25 per cent
nitrogen and remaining 25 per cent potassium a week
before panicle initiation stage.