1. oder to incoorate fetilizers,reduce the oilto afincr tilth.levcl the surface,ot cunttol wecds
Reduced tillage
Reduced tullage lcaes about |` and 30°%crop residuc cover on the sol This may involvc the
usc of a
chisel plow, ficld cultivators, orother implements.
Intensive tillage
Intensive tillage leaves less than 150o crop residue cover This type of tillage is often referred to
as conventional illage.
Conser ation tillage
(onservation tillage leaves at least 30% of crop residue on the soil surtace,. This slows water
movement. which reduces the amount of soil erosion. Conservation tillage also bencfits farmers
by reducing fuel consumption and soil compaction.
Effects of tillage
Positive
Loosens and aerates the top layer of soil.
Helps to mix residue. organic matter (humus), and nutrients evenly into the soil.
Mechanically destroys weeds
Negative
Dries the soil before seeding
Soil Joses nutrients, like nitrogen and fertilizer, and its ability to store water.
Decreases the water infiltration rate of soil.
Chemicalrunofi.
Reduces organic matterin the soil.
Reduces microbes, carthworms, ants, etc.
Destroys soil aggregates
Compaction ofthc soil.
(Plus Theory Lecture 3)
2. Factors determining the methods ofapplication are:
Weed-crop situation
Type ofherbicides
METHODSOFHERBICIDEAPPLICATION
Mode ofaction and selectivity
Environmental factors
Cost and convenience ofapplication
Dependingon the target site,the herbicides are classified into
1. Soil applied herbicides
2.Foliage applied or foliar herbicides
Different methods by which these herbicides are applied are tabulated below:
1. Surface
3. Band
Soilapplication
2. Sub surface
4. Fumigation
5. Herbigation
1.Soil application ofherbicides:
() Surface application
(ii). Subsurface application
for controllingperennial weeds.
i.
(ii). Band application
ii.
(v).Herbigation
iii.
Foliarapplication
1V.
Blanket spray
Soilactive herbicides are applied uniformly on the surface of the soil either by spraying or by
broadcasting.
Directed spray
Protected spray
It isthe application of herbicides in a concentrated band, about 7-10 cm below the soil surface
Spottreatment
Application to a restricted band along the crop rows leaving an untreated band in the inter-rows.
(iv). Fumigation
Application of volatile chemicals in to confined spaces to produce gas that will
destroy weed seeds iscalled fumigation.
It is the application ofherbicides with irigation water both by surface and sprinkler systems
2. Foliar application
3. (i)Blanket spray
It is the uniform application of herbicides to standing crops without considoring ihe locationof
the crop. Only highly selective herbicides are used here
(ii).Directed spray
Itis the application of herbicides on weeds in between rows of crops by dirceing he sprAy only
on weeds avoiding the crop.
(iii). Protected spray
I1 is a method of applying non-selective herbicides on weeds by covering thc crops which are
Wide spaced with polyethylene covers etc. It is usually done o snall reas having
serious weed infestation tokill it and to prevent its spread.
4. PracticalNo
Broadcasting
Itrefers to spreading fertilizers uniformly all over the field.
i)Broadcasting (Basalapplication)
METHODS OF FERTILIZER APPLICATION
ii) Top dressing
The main objectives of broadcasting the fertilizers at sOwing time are to uniformly distribute the
fertilizer over the entire field and to mix it with soil.
It is the broadcasting of fertilizers particularly nitrogenous fertilizers in closely sown crops like
paddy and wheat, with the objective of supplying nitrogen in readily available forrm
Disadvantages of broadcasting
i)Nutrients cannot be fully utilized by plant roots as they move laterally over long distances.
ii) The weed growth is stimulated all over the field.
b)Placement
1.
1i)Nutrients are fixed in the soilas they come in contact with a large mass of soil.
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Itrefers to the placement of fertilizersin soil at aspecific place
2. Placement offertilizers is normally recommended when the quantity offertilizers to
apply is small,development ofthe root system is poor, soil have alow level offertility
and to apply phosphatic and potassic fertilizer.
The most common methods ofplacement are as follows:
i) Plough sole placement
1, In this method, fertilizer is placed at the bottom of theplough furrow inacontinuous
band during the process ofploughing.
2. This method is suitable for areas where soil becomes quite dry i) Deep placement
iii)Localized placement
Itrefers tothe application offertilizers into the soil close to the plant inorder to supply the
nutrients in adequate amounts to the roots ofgrowing plants.
a) Drilling:In this method, the fertilizer is applied at the time ofsowing by means ofa seed-cum
fertilizer drill
5. b) Side dressing:
It refers to the spread of fertilizer in between the rows and around the plants.
c)Band placement: Itrefers to the placement of fertilizer inbands.
Pellet application
1. Itrefers to the placement of nitrogenous fertilizer inthe form of pcllets 2.5 to 5
cm deep
between the rows of the paddy crop.
2. The fertilizer is mixed with the soilin the ratio of 1:10 and made smallpellets of
convenientsize to deposit in the mud of paddy fields.
Foliar application
I: lt reters to the spraying of fertilizersolutions containing one or more nutrients on the
foliage of growing plants.
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2. Several nutrient elements are readily absorbed by leaves when they are dissolved in water
and sprayed on them.
3. The concentration ofthe spray solution has to be controlled, otherwise seriousdamage
may result due to scorching of the leaves.
4. Foliar application is effective for the application ofminor nutrients like iron, copper,
boron, zinc and manganese. Sometimes insecticides are also applied along with
fertilizers.
Application through irrigation water (Fertigation)
1. It refers to the application of watersoluble fertilizers through irrigation water.
2. The nutrients are thus carried into the soil in solution.
3. Generally nitrogenous fertilizers are applied through irrigation water
Aerial application.
In areas where ground application is not practicable, the fertilizer solutions are applied by
aircraft particularly in hilly arcas, in forest lands, in grass lands or in sugarcane fields etc
6. Foliarfeedingis a
technique offeeding plants by applying liquid fertilizer directlyto their
leaves. Plants are able to absorb essential elementsthrough their leaves. The absorption takes
place through their stomata and also through their epidermis.
Condition favouring foliar applications
1) Late evening:
2) Early morning: after 6:00
p.m.
before 9:00 a.m.
Foliar feeding
3) Low temperature 18-19oC (Ideal 210C)
4) relative humidity GREATERTHAN 70%
Advantages of foliar nutrition
5) Within 24 to 48 hours after afoliar application may reduce the application
effectiveness, as not all nutrient materials are immediately absorbed into the
plant tissue
It helps in rapid correctionof nutrient deficiency
Foliar spraying can be combined with other sprayings like insecticides
When the soil is deficient in nutrients foliar application is beneficial
When aquick growth response is desired foliar application can be sprayed
It willhelp during high fixation ofPand K
Limitations
Foliar spray can be applied when adverse condition like root rot disease, drought
condition etc. were noticed in field
Only use smallamounts of fertilizer
Foliar spray can also be given when there is not adequate moisture in top soil to
absorb the nutrients by plant roots
Improved yield and yield quality parameters
It willcause scorching or burning effect if concentration of the spray is high
Itrequires sticking agent to get more efficiency
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Toobtain good efficiency of spray leaf area should be large
Only small quantities offertilizers can be applied through foliar application
Foliar application efficiency is depends on climatic conditions like temperature,
humidity, windvelocity etc.
Cost ofmultiple applications can be prohibitive.
Possibility offoliar burn (with high concentrations
8. Fertilizer
Urea
SSP
MOP
DAP
Fertilizer required
Solutions steps:
Fertilize Calculations
Nutrient content
(%)
46% N
16% P205
60% K20
18% N
46% P205
100
5)MOP =40 x1.67 =66.67 kg /ka
Nutrient content (%)
1) First we have to work out complexfertilizer
(i.e,DAP for phosphorus =60x2.17 =130.43kg )
2) DAP not only supplied 60kg of Pbutalsocontains 18% N
3) Therefore we haveto deduct 18% Nfrom 130.43kg of DAP.
130.43kg DAP contains =(18/100)x130.43 =23.48 kg N.
4) Therefore 23.48 kg Nrequirement is fulfilled through DAP.
Rest 97kg N(120-23.48) hastobe supplied through Urea
Example: Calculate the quantity of urea, DAP and MOP is required to supply the recommended
dose fertilizer 120:60:40 kg NPK/ha
Urea for 97 kg N= 97 x2.17 =210.87 kg/ha
Factor
2.17
6.25
1.67
5.55
2.17
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X Recommended dose of fertilizer
Therefore, quantity of urea, DAP and MOP is require to supply 120:60:40 kg NPK/ha is
210.87kg, 130.43kg and =66.67kg respectively.
9. Practical No
Mineral Nutrition isdefined as the naturall 0euriy inoreaunic nutricnt lound in the soil that is
essential tor the proper functioning plant. Minerals are vital elements nccessary lor both the
plants and animals
Nutrients which arerequircd bv plants in very smallamounts are ternicd as Micro Elcments or
macronutrients. Some of them include boron. copper. mangancse. Iron, chlorine, and
moly bdenum.
Nutrient Functions
Nutrientswhich are required by plants in larger amounts are termed as Macronutrients. Some of
thenn include sulfur. nitrogen,carbon, phosphorus, calcium, potassium and imagnesium.
Role of Nutrients
Letus have adetailed look at the mineral nutrition notes to explore the role of micronutrients and
macronutrients in maintaining human health.
Copper
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Balancing function: Sonme salts or minerals act against the harmful effects of he other
nutrients thus balancing each other.
Maintenance of osmotic pressure: Several minerals cell sap is present in organic or
inorganic form to regulate the organic pressure of the cell.
Influencing the pH of the cellsap: Different anions and cations has an influence on the
pH of the cellsap.
Construction of the plant body:Carbon, Hydrogen, and Oxygen are elements that help
to construct the plant body by entering protoplasm and constitution of the wall.
Micronutrients
Catalysisof the biochemical reaction:Certain elements like zinc, magnesium, calcium
and copper act as metallic catalysts in biochemical reactions.
Effects of Toxicity: Certain minerals like arsenic and copper has a toxic effect on the
protoplasn under specific conditions.
It is acomponent of oxidase, cytochrome oxidase, phenolases and ascorbic acid oxidase
that is responsible for activating the enzymes.
Copper plays a vital role in photophosphorylation.
It also helps to balance carbohydrate-nitrogen regulation.
Manganese
It is necessary for photosynthesis during the photolysis of waler.
10. Zinc
The mineral is required for the synthesis of chlorophyll.
I acts as an activator of nitrogen metabolism.
l1 is essential for the synthesis of tryptophan. metabolisn ol carbohydrates and
phosphorus.
Ii is a constituent of cnzymes like alcohol dchydrate-gas, carbonic anhydrasc. lactic
dehydrogenase. hexokinase. and carboxypeptidase.
Macronutrients
Functions of certain macronutrients are stated below:
Phosphorous
Phosphorous boosts fruit ripening and root growth in a healthy manner by helping
translocation ofcarbohydrates.
They are found abundantly in fruits and seeds.
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Deficiency of Phosphorus leads to premature fall of leaves and they turn purplish or dark
green in color.
Nitrogen
It is present in various coenzymes, hormones, and ATP etc.
Nitrogen is avital constituent of vitamins, nucleic acids, proteins and many others.
Deficiency of nitrogen leads to the complete suppression of flowering and fruiting.
impaired growth, and development of anthocyanin pigmentation in stems.
Potassium
Potassium is the only monovalent cation that is necessary for plants. It acts as an enzyme
activator including DNA polymerase. The deficiency of potassium leads to Mottled chlorosis.
11. Practical No.
1. Spacing - 75 cmx30cm
1. Caleulate the expected yicld of maize grainin tha' from the detailsgiven below:
2. Average no.of cobs plant
3. Average no. of grain row cob
4. Average no.of sccds grain row
Solution
$. Test weight of secds(1000 secd weight) 250 g.
2. Grain weight plant' (g) =
1. Grain no. plant' =Cobs plant" Xrain rows cob'X No. of grainsrow'
3. Plant population ha'
4.Grain yield ha
- 10
YieldCaleulation
=2X10X 25=500
=
- 25
No. of grains plant X
500 x250(g)
1000
1000
55,55,500
5555.5
1000
=5555500 g ha
Yield plant" X Plant population ha
=
125 g
10,000 sq. m.
125 (g) X 44,444
1000
Spacing plant (0.75 mX0.30 m)
- 5555.5 kg ha
-=5.5555 t ha
Test weigh(g)
Answer: Yield of maize grain would be 5.56 t ha'
= 44,444 ha
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