RLO%209

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RLO 9 Lesson Chemical Fertilizers as a component
of INM in Rice

• After completing this lesson, you will be able
  to
• Understand the role of different fertilizers as a
  component of Integrated nutrient management .

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Chemical fertilizers as a component of integrated
nutrient management in rice

• Chemical fertilizers supply largest amounts of
  nutrients to rice crop even when INM practices
  are followed.
• On an average rice crop removes 20-27 kg N, 8-18
  kg P2O5 and 20-40 kg K2O per tonne of grain
  harvested.
• Different kinds of chemical fertilizers are
  available to supply nutrients to the rice crop.

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Nitrogenous fertilizers

• A dose 100-150 kg N/ha is generally recommended
  for high yielding varieties of rice. Hybrids
  where yield potential is 8-10 t/ha will need
  still higher doses of N (180-200 kg N/ha).
• Fertilizers used are Urea, ammonium sulphate,
  DAP, CAN, Nitrification inhibitors coated urea
  and slow release fertilizers

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Improving nitrogen use efficiency of rice

• Nitrogen use efficiency (NUE) of rice, especially
  under lowland conditions, is low, i.e. 30-50.
• Significant proportion of N is lost by
  denitrification, ammonia volatilization and
  leaching etc. in rice.
• NUE can be increased by split application, deep
  placement and use of nitrification inhibitors and
  slow-release N fertilizers.
• Two split doses are recommended for short
  and medium duration varieties, while 3 split
  doses are recommended for long duration
  varieties.
• Nitrification inhibitors can also be used to
  reduce N losses.
• contd

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• Nitrification inhibitors retard the nitrification
  process in soil and thereby reduce the N losses
  by leaching and denitrification.
• A number of chemicals have been reported to
  have nitrificatioin inhibiting properties. The
  chemicals most widely tested are N-Serve
  (2-chloro 6(trichloromethyl) pyridine), AM
  (2-amino-4-chloro-6 methyl pyrimidine), DCD
  (dicyandiamide) and ST (Sulphathiazole).
• Increased rice yields and increased NUE in India
  has been reported for N-Serve, AM, ST and DCD.
• Neem oil coated urea (500-1000 ppm ) enhances
  grain yield and nitrogen use efficiency in rice.
  This product is now available in the Indian
  market.
• Sulphur coated urea is also a useful fertilizer
  for rice.

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Phosphatic fertilizers

• Single super phosphate, diammonium phosphate
  (DAP), rock phosphate and NPK fertilizers are
  the important sources to supply P to rice.
• Rice needs, on an average, 40-60 kg P2O5/ha
• P application is generally recommended at final
  puddling before transplanting/final
  ploughing or at broadcasting in the case of
  direct seeded rice.
• In the case of non-availability of fertilizer
  in time, it can be top-dressed within 30 days
  of transplanting and at the most may be
  extended to 40 days on medium soils.
• The general practice is to broadcast P
  fertilizers just before final puddling in
  the case of transplanted rice and final
  ploughing in the case of direct seeded rice.
  contd.

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• Dipping of roots of rice seedlings in P-slurry
  has also been found reasonably good.
• There has been considerable interest in the
  direct use of rock phosphate (RP) in rice.
• Rock phosphate needs to be generally applied
  3-4 weeks before transplanting and should be
  incorporated in soil for better results. Some
  workers also recommend higher rates of
  application as compared to water soluble P
  fertilizer.
• Higher efficiency of RP in acid soils is
  due to lesser P fixation.
• Particle size of RP is an important property
  that affects its efficiency.

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Potassic fertilizers

• Response of kharif rice is generally higher than
  rabi rice. This could partly be due to the fact
  that disease incidence in rice is more
  during kharif season.
• Potassium application reduces the severity of
  bacterial diseases of rice. Severity of fungal
  diseases such as brown leaf spot, Cercospara
  leaf spot, sheath blight, stem rot and
  Helminthosporium sp is also reported to be
  reduced by K application.
• There are mainly two potassium fertilizers
  namely, muriate of potash (MOP) (KCl)
  containing 60 K2O and sulphate of potash
  (SOP) (K2SO4) containing 48 K2O.
• Due to high costs mostly MOP is used for rice.
  Potassium application is mostly recommended at
  the time of sowing/transplanting.

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Sulphur

• Substitution of high analysis fertilizers such
  as urea and DAP for ammonium sulphate and single
  superphosphate has been the main cause for wide
  spread S deficiency in Indian soils.
• In general, rice responds to 20-40 kg/ha.
• There are 2 kinds of sources of S. The first
  kind are the popular fertilizers containing S
  as the nutrient other than that for which
  fertilizer is applied. For example, single
  superphosphate (SSP) is marketed as phosphate
  fertilizer but contains 12 S.
• The other kind of sources of S are those
  materials which are marketed and used only as a
  source of S. These are referred to as
  S-fertilizers and include elemental S, gypsum,
  iron pyrites and phosphogypsum (a byproduct
  of phosphoric acid industry). Most S is
  applied to soil at sowing.

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Micronutrients fertilizers

• Deficiency of 3 micronutrient have been reported
  in rice-growing areas of India. First of all
  zinc deficiency in rice fields was noticed in
  tarai soils. Later deficiency of Fe was
  noticed on sandy soils of Punjab. Of late
  boron (B) deficiency in rice has been reported
  on highly calcareous soils of Bihar.
• Zinc sulphate and zinc oxide are the important
  zinc fetilizers available in India.
• Application of 25 kg zinc sulphate
  (heptahydrate)/ hectare is generally recommeded
  in India (for rice). Dipping rice roots in 2-4
  ZnO suspension has also been found to be very
  effective.
• If zinc is not applied in soil at transplanting/
  sowing and zinc deficiency symptoms appear,
  foliar spray of 0.5-1.0 zinc sulphate is
  recommended. contd..

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• Fe chlorosis in rice is better controlled by
  foliar spray of 0.5 Fe-sulphate.
• Soil application of B should be made when
  deficiency of B has been established.
  Indiscriminate use may result in toxicity of
  plants. When foliar application is must, a 0.2
  borax solution (with lime twice the weight of
  borax) is recommended to avoid injury to
  foliage).

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Micronutrients fertilizers

• Zinc Sulphate - Crystalline (ZnSO4.7H2O) - 21 Zn
  .
• Zinc Sulphate Mono Hydrate - Powder (ZnSO4.H2O) -
  33 Zn
• Ferrous Sulphate - Crystal/Powder (FeSO4.H2O) 19
  Fe
• Copper Sulphate - Crystal/Powder (CuSO4.5H2O) -
  24 Cu
• Manganese Sulphate - Powder (MnSO4.H2O) - 30.5
  Mn.
• Chelated Zinc - Powder - 12 Zn - EDTA

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Summary
Sustainable rice production through integrated
nutrient management will require integrated
strategies for the use of various sources of
plant nutrients in conjunction with efficient
soil, water and crop management practices. Due
attention is required to improve the use
efficiency of the expensive fertilizer resource.
Different sources of fertilizers discussed in
this presentations would help in improving the
rice productivity .