1. Chemical Fertilizers as a Component of Integrated Nutrient Management
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2. Chemical Fertilizers as a Component of Integrated Nutrient Management
Introduction
Fertilizer can be defined as
a mined, refined or manufactured product containing one or more essential plant nutrients in available or potentially available forms and
in commercially valuable amounts without carrying any harmful substance above permissible limits.
Many prefixes such as synthetic, mineral, inorganic, artificial or chemical are often used to describe fertilizers and these are used interchangeably.
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3. Chemical Fertilizers as a Component of Integrated Nutrient Management
Introduction
Fertilizers have been traditionally classified into following two group, depending upon the number of nutrients available in them.
Straight fertilizers
Complex/ compound
fertilizers
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4. Chemical Fertilizers as a Component of Integrated Nutrient Management
Straight fertilizers
Straight fertilizers contain one of the three major nutrients N, P or K.
This is a traditional term referring to fertilizers that contain and are used for one major nutrient as opposed to multinutrient fertilizers.
For secondary nutrients, these include products containing elemental S, magnesium sulphate, calcium oxide, etc.
In the case of micronutrients, borax, Zn and Fe chelates and sulphate salts of micronutrients are straight fertilizers.
However, the term is not often used for micronutrient carriers.
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5. Chemical Fertilizers as a Component of Integrated Nutrient Management
Complex/compound fertilizers
Complex or compound fertilizers contain at least two out of the three major nutrients.
They are produced by a chemical reaction between the raw materials containing the desired nutrients and they are generally solid granulated products.
These include both two-nutrient (NP) and three nutrient (NPK) fertilizers.
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6. Chemical Fertilizers as a Component of Integrated Nutrient Management
Complex/compound fertilizers
These are also referred to as multinutrient fertilizers, but do not include fertilizer mixture or bulk blends as no chemical reaction is involved.
Multinutrient fertilizers can be further classified into:
Complex/compound fertilizers;
Mixtures and bulk blends;
Multimicronutrient carriers;
Fortified fertilizers.
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7. Chemical Fertilizers as a Component of Integrated Nutrient Management
Mixed Fertilizers
Mixed fertilizers are advantageous because they reduce cost of application and ensure better mixing in soils.
These fertilizers can be used on all crops grown under different conditions of climate, soil and crop husbandry.
Their use has been advantageous and is the effective way to supply the fertilizer requirements of a crop.
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8. Importance of Mixed Fertilizers
Chemical Fertilizers as a Component of Integrated Nutrient Management
Importance of Mixed Fertilizers
Application of mixed fertilizers save labour cost.
Granulated mixed fertilizers are good source because many nutrients can be applied at a time.
Nutrients are distributed evenly in the crop root zone
Fertilizer use efficiency is increased
Mixtures prepared by farmers are cheaper than purchased from the market.
The firm and free flowing granules are safe for spreading by hand.
Mixed fertilizers are also well suited for application by machine.
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9. Chemical Fertilizers as a Component of Integrated Nutrient Management
Neem Coated Urea
Urea is most widely used fertilizer of nitrogen & is produced by reacting ammonia with carbon dioxide under pressure and high temperature.
Urea is placed in reduced zone in submerged soil to minimize volatilization and denitrification losses.
To facilitate deeper placement, urea is manufactured as super granules and made into bolls.
To reduce nitrification losses, ordinary prilled urea is coated with neem oil. At present, it is being manufactured by the leading fertilizer manufacturers in the country.
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10. Chemical Fertilizers as a Component of Integrated Nutrient Management
Neem Coated Urea
Good paddy crop due to neem coated urea
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11. Chemical Fertilizers as a Component of Integrated Nutrient Management
Advantages of neem coated urea
Slow release of nitrogen by extending the urea hydrolysis for a longer period.
Inhibits nitrification.
Reduces nitrogen losses by leaching and dentrification.
Increased nitrogen use efficiency in paddy.
Regulates supply of nitrogen coinciding with the crop growth and development.
Increases growth and grain yield of paddy
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12. Chemical Fertilizers as a Component of Integrated Nutrient Management
Mode of Application
Application of recommended dose of fertilizers in two or three splits during crop period is known as split application of fertilizers.
The number of split application has to be more in light soils and less in heavy soils.
Nitrogen is applied in more splits for long duration crops. The stage of application is also important.
In cereals, nitrogen is applied at tillering and panicle initiation stages in addition to basal application.
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13. Chemical Fertilizers as a Component of Integrated Nutrient Management
Time of Application
Nitrogenous fertilizers are generally recommended to be applied in splits, depending upon climate, soil and crops.
Application of phosphatic and potassic fertilizers to field crops is recommended as basal. In a Phosphorus deficient field, a delayed application is better than no application at all.
In tree crops, giving all phosphorus and potassium only once as basal is not a practical preposition because of their long life.
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14. Methods of Fertilizer Application
Chemical Fertilizers as a Component of Integrated Nutrient Management
Methods of Fertilizer Application
Soil Application / Broadcasting
Application of fertilizer uniformly on the soil surface is known as broadcasting of fertilizers.
This is done either before sowing of the crop or in the standing crop.
Broadcasting is the most widely practiced method in India due to ease in application.
Broadcasting is advantageous with solid and soluble fertilizers.
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15. Methods of Fertilizer Application
Chemical Fertilizers as a Component of Integrated Nutrient Management
Methods of Fertilizer Application
Broadcasting is
The entire dose of phosphatic and potassium fertilizers are applied by broadcasting before sowing.
Because of their low mobility in soil, these fertilizers are incorporated into the rooting zone.
Broadcasting of Fertilizer
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16. Chemical Fertilizers as a Component of Integrated Nutrient Management
Row or Band Placement
When localized fertilizer placement (putting the fertilizer only in selected places in the field) is used, the fertilizer is concentrated in specified parts of the soil during planting, which may be either in bands or strips under the surface of the soil or to the side of, and below, the seed.
This can be done either by hand or by special planting and/or fertilizer drilling equipment (seed-cum-fertilizer drill).
It is preferably used for row crops, which have relatively large spaces between rows
(maize, cotton, and sugar cane);
or on soils with a tendency to phosphate and potassium fixation;
or where relatively small amounts of fertilizer are used on soils with a low fertility level
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17. Chemical Fertilizers as a Component of Integrated Nutrient Management
Side-dressing
Applying fertilizer as side-dressing is the practice of putting it to the side of widely spaced plants grown in rows such as maize, cotton and sugar cane.
Trees or other perennial crops also are normally side-dressed.
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18. Chemical Fertilizers as a Component of Integrated Nutrient Management
Foliar application
Foliar application is the most efficient method of supplying micronutrients (but under a stress situation for the crop also N or NPK) which are needed only in small quantities and may become unavailable if applied to the soil.
To minimize the risk of leaf scorch, the recommended concentration has to be respected and spraying should preferably be done on cloudy days and in the early morning or late afternoon (to avoid an immediate drying of the droplets).
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19. Determining fertilizer needs
Chemical Fertilizers as a Component of Integrated Nutrient Management
Determining fertilizer needs
To determine fertilizer needs for crops and soils, knowledge of the following two things is essential:
Which nutrients are needed in the fertilizer?
How much of each nutrient is needed to get the highest or most profitable (optimum) yield?
There are several approaches to finding the answers to these questions. It includes:
Nutrient hunger signs on growing crops (deficiency symptoms).
Soils tests or analyses to determine the fertilizer nutrients and amounts needed.
Plant and/or plant tissue tests in the field.
Fertilizer field trials
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20. Different methods of fertilizer application
Chemical Fertilizers as a Component of Integrated Nutrient Management
Different methods of fertilizer application
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21. Chemical Fertilizers as a Component of Integrated Nutrient Management
Let us sum up
The combination of organic manures and chemical fertilizers (Integrated Plant Nutrition Management, IPNM) provides the ideal environmental conditions for the crop, as the organic manure/organic matter improves soil properties and mineral fertilizers supply the plant nutrients needed.
However, organic manure/organic matter alone is not sufficient (and often not available in large quantities) for the level of crop production the farmer is aiming at. Mineral fertilizers have to be applied in addition.
Even in countries where a high proportion of organic wastes is utilized as manure and to supply organic matter, mineral fertilizer consumption has risen steadily.
The correct kind, time, mode and method of fertilizer application is very important in realizing maximum benefit from the fertilizer use.
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