1. Modern approaches for nitrogen management in rice include site-specific nutrient management, leaf color charts, chlorophyll meters, remote sensing, crop simulation models, use of nanoparticles, controlled release fertilizers, nitrification and urease inhibitors, laser land levelling, and integrated nutrient management. These approaches aim to improve nitrogen use efficiency and minimize nitrogen losses.

1. MODERN APPROACHES FOR
NITROGEN MANAGEMENT IN RICE
PRESENTED BY:
PANKAJ LOCHAN PANDA
B.Sc.(Hons.)Ag 3RD YEAR, I SEMESTER
ROLL-18230AGC027
Institute of Agricultural Sciences, BHU
SUBMITTED TO:
Dr. ARDITH SANKAR
Subject: AGR 311-Practical Crop Production-1(Kharif): (credit- 0+1)

2. Introduction
 Among plant nutrients, nitrogen is the most important. Its importance as a
growth and yield determining nutrient led to rapid and large increases in N
application rates, but often with poor use efficiency. .
 Nitrogen management requires special attention in its use so that large
losses can be minimised and efficiency maximised.
 Cereals are the major source of food and rice( Oryza sativa), is the staple
food for nearly half of the world’s population.
 Global production of rice is more than 740 million tons and world’s 90% of
rice produced and consumed in Asia. India is the 2nd largest producer of rice
after China.
 Fertilizer is one of the major factors for continuous increase in rice
production and more than 20% of nitrogenous fertilizers produced in world
wide is used in the rice fields of Asia
 India placed third in production and second in consumption of chemical
fertilisers in the world.
 The total nitrogen production, import and consumption in India was 13.43,
3.43 and 16.96 million tons respectively.

3. Ill effects of Nitrogen mismanagement
 Besides higher economic inputs due to low NUE, rice and other crops
become more susceptible towards pest and disease, when supplied with
imbalanced nitrogen.
 Higher doses of nitrogen enhances mining of soil nutrients that are not
applied or applied inadequately, thus leading to deterioration of soil
fertility. Such soils may require more fertilizers over time to produce
optimum yields.
 N2 applied in excess of crop demand is lost through volatilization,
denitrification and leaching, which encourages climate change and
ground water pollution respectively.
 Increase in nitrate content of groundwater in some intensively cropped
areas has been reported, which is obviously due to leaching of nitrates
beyond crop root zone and this is potentially harmful, as it is used for
drinking purposes in most of the rural areas.

4. Modern approaches for N2
management in rice
 To overcome the abovesaid problems associated with excess or
mismanaged nitrogen application, we have to adopt modern and
advanced tools for increasing NUE and thereby decreasing nitrogen
losses.
 As in several studies show the major application of nitrogen is done
in rice field all over the world, thus leading to higher
mismanagement of nitrogen in lieu of getting more output in case of
rice.
 Therefore researchers’ prime concern now to manage the nitrogen
application in particular in rice and in general for major cereal crops
also.

5. 1.Site specific nutrient management(SSNM)
 Current approach of fixed time and fixed rate fertilizer application is not
helpful in achieving NUE as this doesn’t consider the existence of large
variability in inherent soil nutrient supply and site specific crop response to
nutrients among farms.
 SSNM was developed in Asia for rice to manage farm nutrient variability.
 It emphasizes on feeding of nutrients to crops when needed in optimum
amount(plant- based approach).

6. Cont.
SSNM comprises following steps:
Step1: Establish an attainable yield target:
 Rice yields are location and season specific depending upon climate,
cultivars, and crop management.
 Yield target is the estimated grain yield attainable with farmers crop
management when N,P and K constraints are overcome.
 Amount of nutrient is directly related to crop yield. So, the yield target
indicate total amount of nutrient must be taken up by crop.
Step2: effectively use existing nutrients:
 SSNM promotes the optimal use of indigenous nutrients from soil, crop
residues, manure, and irrigation water. It can be estimated from Nutrient-
limited yield.
Step3: Apply fertilizers to fill the deficit between crop needs and indigenous
supply.
SSNM saves 10%N, increases 25% yield and more uniform N application in
Rice-wheat cropping sequence as compared to Farmers Fertilizer Practices.

7. Full
application of
N,P and K
N omission
plot
Phosphorus
omission plot
Potassium
omission plot
Difference of crop yield between 1st Plot and 2nd Plot= amount
of Nitrogen to be applied from outside
Nutrient omission Plot technique

8. 2.Leaf Colour Chart for N2 management.
 LCC is cheaper method used for determining timing and amount of N fertilizer
application in rice.
 It has 4 strips and colour of the strips ranges from yellow green to dark green,
green colour indicates sufficient Nitrogen while yellow shows its deficiency.
 LCC offers to manage N need in real time for their efficient use.
 Farmers apply N in splits but no. of splits, amount of N and the time of
application varies, so LCC is more useful, simple and cheaper method for
assessing and managing qualitative leaf nitrogen status for a large area by the
farmers .
 It saves 40% of N as compared to blanket.

9. 3.Chlorophyll meter for nitrogen management
 SPAD- simple, quick and non destructive in-situ tool.
 It allows fine -Tuning of nitrogen management in field condition.
 It measures the ratio of radiation transmittance from 2 wavelengths (
red 660nm, strongly absorbed by chl. and near infra red 940nm, not
absorbed by chl.)
 The linear relationship between SPAD value and N used for N
management.
 For convenience, 37 value as found to be critical for
Improved NUE in short statured indica rice variety.
 If value falls below 37 each time a 30 kg N/ha is applied
to increase efficiency.
 N efficiency: 6.97%
 Save 25% N

10. 4. Use of remote sensing and GIS
 More efficient for large scale application.
It is of 2 types:
 a)Green seeker sensor: remotely sensed indices like NDVI(Normalised
Difference Vegetation Index) are used.
 NDVI=
𝐩𝐍𝐈𝐑 −𝐩𝐫𝐞𝐝
𝐩𝐍𝐈𝐑+𝐩𝐫𝐞𝐝
(pNIR= reflectance of near infra red -800-1000nm,
pred= reflectance of 660-6680nm)
 Can save 68 kg N/ha. compared to Farmers’ fertilizer practices.

11. Cont.
b) Crop canopy sensor:
 Works on same principle as that of Green seeker.
 Visible light produced- yellow(amber), so called as amber sensor and the
index is amber index

12. 5. Crop simulation model
 Quantitative tools.
 Predict the N application time and amount.
 It simulates or imitates the behaviour of a real crop by predicting the
growth of its components.
Types of models:
 Statistical & empirical
 Mechanistic
 deterministic
 Stochastic
 Static
 dynamic

13. Steps in modelling
 Define Goals
 Define systems and its boundaries
 Define key variables in system(state, rate, driving, auxiliary)
 Quantify relationship (evaluation)
 Calibration
 Validation
 Sensitivity analysis

14.  As the simulation model predicts the time of application of N
fertilizer, it also predicts right amount required by the plant, thus
avoiding excessive use of N fertilizers and also improves N use
efficiency.
Crop simulation model used for N management in rice are:
 DSSAT(Decision Support System for Agrotechnology Transfer)
model
 CERES(Crop Environment Resource Synthesis) model
 WOFST(World Food Study) model

15. 6)Use of nanoparticles
 Ceria nanoparticle(CeO2) application resulted in increase of N
level(6-12% in root and 22-30% in shoot) when applied in low doses
and reduced the N(9% in root and 6% in shoot) when there was High N
stress in rice crop.
 Its treatment also enhanced the activities of enzymes involved in N
assimilation, i.e. Glutamic synthase, Glutamine Oxoglutarate
Aminotransferase and Glutamate Dehydrogenase
 It enhance antioxidant enzyme system against N stress in rice.

16. 7) Smart Fertilizer
 It provides significant dosage reduction and yield improvement in an
environment-friendly way.
 It is a breakthrough for low fertilizer use efficiency of water-soluble
N fertilizer such as Urea, ammonium sulphate and ammonium
carbonate.
 Nitrification inhibitors, urease inhibitor, slow and control release
fertilizers increase N use efficiency, productivity and yield and
reduce N losses through better coordination of N availability with
plant demand.

17. a) Control release fertilizer:
 Control Release Fertilizer(CRF) are coated or encapsulated with organic or
inorganic materials with control plant nutrient release pattern, rate and
duration.eg. Polymer, neem, S, resin, Mg/NH4 phosphate etc
 The release rate is optimised to meet the changing crop nutrient
requirements in a designed pattern.
 It provides plant nutrient that are usable for a longer duration than normal.
b)Slow Release Fertilizers:
 Consists of compounds that are typically having low water solubility and
reduce urease or other biocatalyst on enzymatic hydrolysis.
 The release, rate, pattern and duration are not regulated because they rely
on microbial organisms whose efficacy depends on temperature and
humidity.
 CO 𝑁𝐻2 2 + 2𝐻2O Urease (NH4)2𝐶𝑂3(unstable)
 E.g..: Urea Formaldehyde(38% N), CDU(crotonilidine diurea, 32.5% N),
IBDU( isobutylidine diurea, 32.2% N)

18. c) Nitrification inhibitors:
 Inhibits bacterial oxidation of ammonium ion by reducing the
activity of Nitrosomonas over a certain period of time(4-10 weeks)
 Designed to prevent nitrate loss by leaching or producing nitrous
oxide by denitrification by holding N in ammonium form longer and
thus increasing the NUE.
 Delay the conversion of ammonium to nitrate avoiding unwanted
high levels of nitrate in plants used for human and animal nutrition.
 It favours the partial ammonium nutrition of plants because plants
need less energy(5ATP/mol. N) to incorporate ammonium into
amino acid
 Nitrification inhibitor are based on the ability to tie-up Copper – a
vital metal used by bacteria for nitrification.
 E.g.: N-serve, nitrapyrin(2-Chloro-6{trichloromethyl}pyridine),
DCD(dicyanamide), etc.

19. d) Urease inhibitors:
 Prevents hydrolytic action of urea by inhibiting urease enzyme.
 It delays the conversion of Urea into ammonium and nitrate.
 They can inhibit urea hydrolysis for 2 weeks or more depending upon soil
and climatic condition, because Urease activity is greatest in field capacity
moisture level and favours a temperature up to 37˚C
 Inhibition of urease activity is due to a tie-up of soil Nickel – a critical
metal constituent of urease enzyme.
But to apply this there should be prerequisites like:
 Effective at low concentration
 Relatively non toxic to higher forms of life
 Inexpensive
 Compatible with urea
 As mobile in the soil as urea
 Ex- Thiourea(36.8% N), NBPT(N-Butyl-Thiophosphoric Triamide), Agro-
10 etc.

20. Schematic diagram of potential smart fertilizer effects in soil-plant
system

21. 7)Laser land levelling
 Improper land levelling is a serious cause of loss of water and
nutrients, resulting in low yield and decreased fertilizer use
efficiency.
 Lll allows smoothing the land surface to within +2 mm of its
average elevation using laser equipped bucket.
 Because of laser land levelling, a 26.46% increase in rice yield
has been recorded. Significant improvement of agronomic
efficiency of N has also been reported in rice field.
 The average increase in agronomic efficiency of N,P and K
under this was 118.2, 130.3 and 130.2% respectively over
traditional levelling

23. 8)Modified forms and application of
Urea
 Urea is placed in reduced zone in submerged soil to minimize volatile
denitrification losses.
 To facilitate deeper placement urea is manufactured as Super granules or
mixed with mud and made into ball.
 To reduce denitrification losses, ordinary urea is coated with neem cake
powder- Coal tar dissolved in kerosene by heating- the liquid tar is
sprinkled on urea and mixed thoroughly to form a thin layer of coal tar on
urea- finally powdered neem cake powder is sprinkled.
 Neemblended urea-mixing of finely powdered neem cake(20-50%) with
urea. It reduce solubility of urea.
 Urea is made into big sized granules of approx. 1g. Known as USG. It is
also made in the form of briquettes. solubility is reduced due to less
surface area.
 Sulphur coating as described above act as controlled release of fertilizer.

24. 9)Balanced fertilization and split
application
 Imbalanced use of N, P and K also leads to low use efficiency of N.
 Attention to NPK is desirable, because 89% of Indian soil are low to
medium in available N, 80% are low to medium in available P, and
50% are low to medium in K
 Efficient use of any nutrient depends on the balanced supply of other
nutrients.
 Nutrient interaction can also be synergistic and multiplicative, not just
additive.
 Split application of N is well known for increasing NUE. When large
quantities of N are applied at a time as a basal dose N, lowers
efficiency.
 2 split doses recommended for short and medium duration, 3 split doses
are for long duration variety.
 Less split doses for heavy soil and more for sandy soil.

25. 10) Integrated nitrogen management
 It refers to the combined use of fertilizer N and organic nitrogen,
which includes N fixed by legumes and other organisms(
azotobacter, azosprillum, BGA etc.) and N supplied by organic
manures such as FYM, compost, vermicompost etc.
 Studies show that application of RDF Urea + FYM increased
agronomic efficiency by 5.4-14.8% in rice.
 The use of biofertilizer is particularly important from the eco
safety point and to reduce cost of cultivation.
 Along with green manuring, brown manuring is also done, which
has added benefits of weed control in rice through space
capture effect.

26. References
 Recent approaches in nitrogen management for sustainable agricultural
production and eco-safety ( An article of Archives of Agronomy)- found
online
 www.knowledgebank.irri.org/ericeproduction/pop_up_nutrient_omission
_plot.htm
 http://www.knowledgebank.irri.org/ericeproduction/pop_up_LCC.htm
 Some Excerpts of the book- Principles of Agronomy by T.Y Reddy and
G.H.S. Reddy
 SlideShare(online) of Real-time nitrogen management and Crop
modelling
 Nano particle’s use for nitrogen management- from:
https://scholar.google.com