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 Fertilizers - Methods of Applying Fertilizer  

The following methods are adopted to apply fertilizers-

Application of fertilizer in solid form

Placement

Inserting or drilling or placing the fertilizer below the soil surface by means of any tool or implement at desired depth to supply plant nutrients to crop before sowing or in the standing crop is called placement. With placement methods, fertilizers are placed in the soil irrespective of the position of seed, seedling or growing plants before sowing or after sowing the crops. The following methods are most common in this category.

  1. Plough - Sole Placement

  2. Deep Placement of Nitrogenous Fertilizers

  3. Sub - Soil Placement

  4. Localised Placement

Plough - Sole Placement: In this method, the fertilizer is placed in a continuous band on the bottom of the furrow during the process of ploughing. Each band is covered as the next furrow is turned. No attempt is usually made to sow the crop in any particular location with regard to the plough sole bands.

This method has been recommended in areas where the soil becomes quite dry up to a few inches below the soil surface during the growing season, and especially with soils having a heavy clay pan a little below the plough-sole. By this method, fertilizer is placed in moist soil where it can become more available to growing plants during dry seasons.

Deep Placement of Nitrogenous Fertilizers - This method of application of nitrogenous and phosphatic fertilizers is adopted in paddy fields on a large scale in Japan and is also recommended in India. In this method, ammonical nitrogenous fertilizer like ammonium sulphate or ammonium forming nitrogenous fertilizer like urea is placed in the reduction zone, where it remains in ammonia form and is available to the crop during the active vegetative period.

Deep or sub-surface placement of the fertilizer also ensures better distribution in the root zone and prevents any loss by surface drain-off. Deep placement is done in different ways, depending upon the local cultivation practices. In irrigated tracts, where the water supply is assured, the fertilizer is applied under the plough furrow in the dry soil before flooding the land and making it ready for transplanting. In areas where there is not too much of water in the field, it is broadcast before puddling. Puddling places the fertilizer deep into the root zone.

Sub - Soil Placement - This refers to the placement of fertilizers in the sub-soil with the help of heavy power machinery. This method is recommended in humid and sub-humid regions where many sub-soils are strongly acidic. Due to acidic conditions the level of available plant nutrients is extremely low. Under these conditions, fertilizers, especially phosphatic and potassic are placed in the sub-soil for better root development.

Localised Placement - This method refers to the application of fertilizers into the soil close to the seed or plant. Localised placement is usually employed when relatively small quantities of fertilizers are to be applied. Localised placement reduces fixation of phosphorus and potassium.

Broadcast

This method refers to the uniform application of fertilizers across the entire soil surface. This may be done before the land is ploughed, immediately before planting, or while the crop is standing. Fertilizers may be broadcast on the surface then tilled or watered into soil, or banded on or beneath the soil surface. Broadcasting is efficient and often the method of choice in areas with perennial plants.

  1. Broadcasting at planting

  2. Topdressing

Broadcasting at planting- This method helps to distribute the fertilizer evenly and to incorporate it with part of, or throughout the plough layer.

Topdressing - Nitrogenous fertilizers containing nitrate nitrogen, like sadium nitrate, calcium ammonium nitrate etc are applied as topdressing to closely-spaced crops. In addition urea is also topdressed. This helps in supplying nitrogen in readily available form to growing plants.

Application of fertilizer in liquid form

  1. Foliar Application

  2. Starter solution

  3. Application through irrigation water

Foliar Application

This refers to the spraying on leaves of growing plants with suitable fertilizer solutions. These solutions may be prepared in a low concentration to supply any one plant nutrient or a combination of nutrients.

  • It has been well established that all plant nutrients are absorbed through the leaves of plants and this absorption is remarkable rapid for some nutrients. Foliar application does not result in a great saving of fertilizer but it may be preferred under the following conditions.

  •  When visual symptoms of nutrient deficiencies observed during early stages of deficiency.

  • When unfavourable soil physical and chemical conditions, which reduce fertilizer use efficiency (FUE).

  • During drought period where in the soil application could not be done for want of soil moisture.

  • There are certain difficulties associated with the foliar application of nutrients as detailed below:

  1. Marginal leaf burn or scorching may occur if strong solutions are used.

  2. As  solutions of low concentrations (usually three to six per cent) are to be used, only small quantities of nutrients can be applied in single spray.

  3. Several applications are needed for moderate to high fertilizer rates, and hence

  4. Foliar spraying of fertilizers is costly compared to soil application, unless combined with other spraying operations taken up for insect or disease control.

Starter Solutions

The use of liquid fertilizers as a means of fertilization has assumed considerable importance in foreign countries. Solutions of fertilizers, generally consisting of N, P2O5, K2O in the ratio of 1 : 2 : 1 and 1 : 1 : 2 are applied to young vegetable plants at the time of transplanting. These solutions are known as 'Starter Solutions'. They are used in place of the watering that is usually given to help the plants to establish. Only a small amount of fertilizer is applied as a starter solution.

Application through irrigation water

Fertilizers are allowed to dissolve in the irrigation stream. The nutrients are thus carried into the soil in solution. This save the application cost and allows the utilization of relatively inexpensive waters.

Application Timing

Fertilizer should be applied when plants need it, when it will be most effective, and when plants can readily take it up. Late summer and early fall fertilization may stimulate new growth that is not winter hardy, and summer drought may interfere with nutrient uptake, but spring, fall, and winter applications are acceptable. A split application may be beneficial, applying half the yearly rate in early spring and the rest in the fall as or after plants go dormant. If water is unavailable, do not fertilize at all - plants will be unable to absorb the nutrients. (During a dry season, application of fertilizer through an irrigation system - can be beneficial.)

Commonly Used Fertilizer in the District:

Inorganic Fertilizer:

  1. Urea

  2. DAP

  3. MOP

  4. SSP

  5. Adhor (NPK with Micronutrient)

Organic Fertilizer:

  1. Dhartikhol

  2. Godrej Vikas Neem

  3. Godrej Vikas (Special)

  4. Adhor Organic Manure

  5. Mahalaxmi Organic Manure

  6. Neemshield

BioFertilizers:

  1. Neemaphos

  2. Azotobacter

  3. Azospirillum

  4. Rhizobium

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