Application of Fertilizer to Soil: 6 Methods

This article throws light upon the top six methods used for the application of fertilizer to soil. The methods are: 1. Broadcasting 2. Placement 3. In Situ Application 4. Foliar Application 5. Starter Solutions 6. Irrigation Water/Fertigation.

Method # 1. Broadcasting:

The fertilizer is spread all over the field with a view to distributing the whole quantity of fertilizer uniformly. This method of fertilizer application should not be practiced where placement of fertilizers in the root zone is feasible because in this practice more amount of fertilizer is required to produce the same yield. Broadcasting of fertilizers is carried out at two stages.

i. At the Time of Planting:

Depending on the crop, broadcasting of the fertilizer is carried out prior to sowing/planting or just before the last ploughing and incorporated in the field.

Broadcasting of fertilizers at the time of planting is generally done under conditions:

(a) When the soils are highly deficient in nitrogen and

(b) When the previous crop has been exhaustive such as sugarcane, jowar, maize, etc.

ii. During Crop Growth Period:

Broadcasting in standing crop is done mainly for nitrogenous fertilizers and mostly for close spaced crop like paddy and wheat. It is called top dressing. Muriate of potash is also applied as top dressing in some crops but this is not a general practice.

Procedure:

Measure the field, divide the field into convenient units, calculate and weight the fertilizer for each unit and spread the fertilizer uniformly on the entire surface of each unit. Division of plot and quantity of fertilizer ensures greater ensures greater uniformity in fertilizer application.

Method # 2. Placement:

Fertilizers are placed in the soil before sowing irrespective of the position of the seed. Placement in standing crop can also be done in widely spaced crop growing in a limited area. For example, in young maize crop fertilizer add can be manually placed 3-4 cm away from the stem.

Placement of fertilizer restricts the surface area of the fertilizer coming in contact with soil particles and thus decreases the fixation of phosphorus and potassium.

i. Plough Furrow or Single Band Placement:

Fertilizer is placed in a continuous band at the bottom of the furrow opened during ploughing. Each band is covered with soil after the application. In single band placement fertilizer is applied on one side of the planted row.

Procedure:

a. Open the furrow with the help of plough.

b. Count the number of furrows and measure the total area of operation.

c. Calculate and weigh the required dose of fertilizer for each furrow and place the fertilizer in the furrow.

d. Cover the furrow with the soil.

ii. Double Band Placement:

In double band placement method, fertilizer is placed and on both the sides of the row. Furrows can be opened with the help of two tyned harrow (if available); keeping the planted row in the centre. After fertilizer is placed, the furrows are covered with the soil by planking.

Placement of fertilizer is generally employed for the application of nitrogenous, phosphatic and potassic fertilizers in the intensive agriculture and in orchards.

Deep placement of fertilizer is generally practiced for application of nitrogenous and phosphatic fertilizers in paddy fields. In this method, 15-20 cm deep furrows are opened with the help of plough and ammoniacal fertilizer is placed in them. They are covered with soil usually by planking.

This operation is done after draining out water from the field. After placement of fertilizer, field can be flooded again. This practice is also useful for concentration dry land areas. In dry land areas moisture is found to be deeper layers of soil. Therefore deep placement can be adopted for both seed sowing and fertilizer application.

iii. Ring Placement:

Ring placement method is mostly practiced for the fruit trees in orchard or for individually grown trees.

Procedure:

i. Open a ring like trench of one foot wide and four to six inches deep around the fruit tree with the help of spade corresponding to the circumference of the shoot system of the tree.

ii. Calculate and weigh the amount of fertilizers for each separately.

iii. Apply fertilizer uniformly in the trench.

iv. Cover the ring with soil.

v. Apply irrigation if required.

Method # 3. In Situ Application:

When fertilizers are applied on a specific spot, it is called ‘in situ’ application or localized application of fertilizer in wide fertilizers.

The following are the kinds of in situ application of fertilizers:

(i) Drill Application:

Drill application refers to the drilling of fertilizer at sowing time. Drilling the fertilizer together with seed should be avoided as it may adversely affect the germination or the young plants may get damaged due to high or concentration of chemicals in the root zone. It is advisable in to use a separate attachment for seed and fertilizer drilling.

This is one of the best methods for applying phosphatic (P) and potassic (K) fertilizers to closely spaced row planted crops like wheat, maize, jowar, bajra etc. This method is also better for applying nitrogenous fertilizers. However, it is safer to drill only small quantities of fertilizers so that germination may not be adversely affected.

Procedure:

i. Attach the fertilizer drilling to be to the plough.

ii. Measure the area of operation.

iii. Calculate and weight the required fertilizers.

iv. Drill the fertilizer taking care of the uniform distribution in the field.

(ii) Dollop Method:

The entire quantity of fertilizer is calculated per plant and is applied on both the sides of the plant with the help of a cup by dividing it into two parts. This is considered to be very efficient method of applying nitrogenous fertilizer in widely spaced crops like cotton and fruit trees.

Procedure:

i. Count the number of plant in the area of operation.

ii. Calculate and weight the required fertilizer.

iii. Put a mark in the fertilizer cup for the desired quantity of fertilizer for each plant.

iv. Dig a hole on both the side of the plants with the help of spade/appropriate tools to a depth of 10 cm.

v. Apply the fertilizer equally in both the holes and cover it with soil.

(iii) Pellet Application:

In pellet method, the fertilizer is mixed with the soil in the ratio of- 1: 10 (one part fertilizer and ten parts of soil) and made into a paste. Then small pellets of convenient size are prepared. These pellets are then applied cost to the field by depositing them in soft mud.

This method is especially useful for the application (of nitrogenous fertilizers in paddy field). This practice greatly increases the nitrogen use efficiency of paddy crop.

Method # 4. Foliar Application:

Foliar application refers to the spraying fertilizer solution on foliage (leaves) of growing plants. Normally, these solutions are prepared in low concentration (2-3%) either to supply anyone plant nutrient or a combination of nutrients.

Advantages:

i. Foliar spraying is useful to correct the nutrient deficiency growing crops.

ii. In extremely dry weather condition where the plants are not able to take up nutrients from soil because of low moisture contents of soil, foliar spray is useful.

iii. When quick response of fertilizer (especially nitrogenous fertilizer) is required.

iv. When the widely spread foliage of plant poses difficulty, for soil application.

Disadvantages:

i. Marginal leaf burns or scorching may occur if strong solutions are used.

ii. As a solution of low concentration, only a small quantity of nutrients can be supplied at a time.

iii. Several applications are needed. This increases the cost of application unless it is combined with other spraying operations.

iv. It cannot be recommended as a sole method of application of fertilizer.

v. Only urea and micro-nutrients can be applied through this method.

Method # 5. 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, and 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.

Method # 6. Irrigation Water/Fertigation:

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 water.

Fertigation:

Intensification of agriculture by irrigation and enhanced use of fertilizers may generate pollution by increased levels of nutrients in underground and surface waters. Therefore, judicious management of plant nutrients available through different fertilizers need be catered.

A higher efficiency is possible with the help of pressurized irrigation system is placed around the plant roots uniformly and allow for rapid uptake of nutrients by plants. Fertigation is the technique of supplying dissolved fertilizers to crops through an irrigation system. Small application of soluble nutrients saves labour, reduces compaction in the field and thereby enhancing productivity.

Need for Fertigation:

i. Uneven growth in fertilizer consumption resulting in state wise, crop-wise variation in consumption.

ii. Mining of nutrient from the soil at alarming rate (soil fertility depletion due to inadequate and imbalanced fertilizer use).

iii. Decline in crop response to fertilizers.

iv. Stagnation in fertilizer production.

v. Weakening relationship between fertilizer use and food grain production.

vi. Increasing dependence on fertilizer imports.

Fertigation is method of applying fertilizers, soil amendments and other water soluble products required by plants during its growth stages either through drip or sprinkler irrigation system.

Advantages of Fertigation:

(i) Increase in crop yield by 25-30%.

(ii) Savings in fertilizers by about 30%.

(iii) Precise application and uniform distribution of fertilizers.

(iv) Nutrients can be applied as per plant requirements.

(v) Acidic nature helps in avoiding clogging of drippers, in cleans up drip system.

(vi) Increase nutrient use efficiency by minimizing loss of nutrients.

(vii) Multi-nutrients including major, secondary and micro-nutrients can applied in a single solution with irrigation.

(viii) Exact concentration of fertilizers can be injected as per requirement of crops.

(ix) Highly leached sandy soils and highly leached soils can brought under cultivation through fertigation as irrigation system.

(x) Cost effective technique due to savings of time, labour and energy.

Characteristics of Fertilizers Suitable for Fertigation:

i. High nutrient content available to crops.

ii. Completely water soluble at field temperature.

iii. Rapid dissolution of fertilizers in irrigation water.

iv. No clogging of filters and emitters.

v. Low content of insoluble matters.

vi. Compatible with other fertilizers.

vii. Minimum content of conditioning agents.

viii. Less interactions between fertilizers and irrigation water.

ix. No drastic changes in pH of irrigation water due to mixing of fertilizer materials.

x. Low corrosive for control head and system.

Compatibility:

Mixing the solutions with two or more than two water soluble fertilizers can sometimes result in the formation of precipitates. Their solutions can ‘be prepared in two separate tanks/containers.

Interactions between Fertilizers Nutrients-Compatibility:

When preparing fertilizer solutions for fertigation, the solubility product of the fertilizer materials must be taken into consideration.

Fertilizer mixtures in the tank/container which reduce the solubility of the mixtures due to the formation of precipitates are as follows:

(i) Calcium nitrates with any sulphates = formation of calcium sulphate precipitation Ca(NO₃)₂ + (NH₄)₂SO₄ = Solution along with CaSO₄ ppt.

(ii) Calcium nitrate with any phosphates = formation of calcium phosphate (CaHPO₄) precipitation

Ca(NO₃)₂ + NH₄P₂PO₄ = Solution along with calcium phosphate ppt. (CaHPO₄)

(iii) Magnesium with mono-ammonium phosphate = formation of magnesium phosphate ppt.

Mg (NO₃)₂+ NH₄H₂PO₄ = Solution along with magnesium phosphate (Mg HPO₄) ppt.

(iv) Ammonium sulphate with KCl/KNO₃= fonnation of K₂SO₄ ppt.

(NH₄)₂SO₄ + KCl/KNO₃ = Solution along with K₂SO₄ ppt.

(v) Phosphorus with iron = Formation of iron phosphate ppt.