Feed the Soil: Approaches to Galvanizing Soil Nutrients via Fertilizers

August 11, 2020

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Soils, given their direct connection to crops, are essential components to the growth of food as they provide crops with vital nutrients and minerals. To ensure food sustainability, it is necessary to provide the soil with the required nutrients at the appropriate time.

Managing soils to produce food is tantamount to upscaling its nutrients. The application of fertilizers to the soil helps improve agricultural productivity and ensure the effective supply of nutrients.

Nutrients Needed for Plant Growth

The 17 essential nutrients for crop growth are grouped as follows:

Group 1

Carbon (C), Hydrogen (H), and Oxygen (O) – These are supplied from air and water.

Group 2

Nitrogen (N), Phosphorus (P), and Potassium (K) – These macronutrients are mostly supplied from the soil, but soil deficiencies and crop removal deplete their availability. Essentially, they must be replaced with supplemental sources mostly from fertilizers.

Group 3

Sulphur (S), Calcium (Ca), Magnesium (Mg) – These secondary nutrients are no less essential but are needed in smaller amounts as fertilizers.

Group 4

Boron (B), iron (Fe), Manganese (Mn), Zinc (Zn), Copper (Cu), Molybdenum (Mo), Chlorine (Cl), Nickel (Ni) – These micronutrients are needed in very small amounts, but play essential roles as catalysts in metabolic processes of crop growth and development.



Types of Fertilisers

Organic Fertilisers: They are natural fertilizers obtained from plants and animals which enrich the soil with carbonic compounds needed for plant growth. They also increase the organic matter content of the soil.

Inorganic or synthetic Fertilisers: These are manufactured by industrial processes.

Fertilizer Use Efficiency

This refers to the determination of the number of nutrients in a fertilizer that is taken up by the crop. This is estimated after the fertilizer is applied to the soil as a proportion of the amount added.

Fertilizers especially inorganic ones have the ability to increase agricultural productivity.

Compound Fertilisers: These refer to fertilizers with two or more nutrients while straight fertilizers contain only one nutrient (single-nutrient).

Mixed fertilizers: These are physical mixtures of two or more nutrients also called multi-nutrient fertilizers

Complex Fertilisers: Fertilisers in which two or more of the nutrients are chemically combined such as Ammonium Phosphates and Nitro Phosphates.

The main components of fertilizers include Nitrogen, phosphorus, and Potassium [NPK].

Fertilizer rating indicates the amount of Nitrogen, Phosphorus, and Potassium it contains.

Methods of Fertiliser Application

This greatly depends on the kind of fertilizer material, cropping system and equipment used and they include the following:


It is a process whereby a recommended rate of fertilizer is spread over the growing area and left to filter into the soil or is incorporated into the soil with a cultivator.

This method is generally used for large field areas with limited time and labor. It can also be adopted to obtain a uniformed distribution of the soil amendment such as a liming material.


This method is mostly used to apply small amounts of fertilizer such as a plant starter. Starter fertilizer applications may help stimulate early plant growth and increase yield.

Side Dressing

This refers to those fertilizer materials applied to the soil after the crop is up and during the early to the mid-growth period of the crop. Nitrogen fertilizers are more often times dressed than Phosphorus or Potassium materials.


Fertigation is when Nitrogen and Potassium are side-dressed by application in the irrigation water. This is applied to crops at intervals during the growing season. Phosphorus is not always applied in this manner because it forms many insoluble compounds with other elements present in the irrigation water.

Foliar Feeding

Foliar nutrition can help to supplement soil nutrition at a critical time for the plant because its nutrients are absorbed and used by the plant quite rapidly.

NPK Fertiliser

This is a synthetic fertiliser that dissolves in water and provides nutrients to crops immediately and constantly because it is readily absorbed by them. Its major constituents are nitrate which supplies Nitrogen (N) to the plant, Phosphate which supplies Phosphorus (P) to the plant and potash which supplies Potassium (P) to the plant.

The aforementioned nutrients have various benefits they allude to crops. They are highlighted below:

Nitrogen: It promotes plant growth by helping to make new tissues. It helps in the development of rich foliage. Nitrogen is the most frequently applied nutrient in non-legume cropping systems.

Phosphorous: It aids in the development of a healthy root in plants, in the growth of flowers, and in building plant resistance to disease. Phosphorus also plays a vital role in photosynthesis.

Potassium: This element regulates the metabolic activity of a plant through osmoregulation. It also helps in the building of plant immunity to certain diseases.

How to Apply NPK

  • They can be applied directly to the soil using pellets, granules, or powders.
    •They can be applied using sprinklers by dissolving the fertilizer, which is very soluble in water
    •For larger farms, machines can be used to apply the fertilizer.

Before carrying out fertilizer application, a farmer should carry out a soil test to determine the nutrients that are lacking to help in choosing the right type of NPK fertilizer that will satisfy the nutrient the needs of the soil.

Note: Learning the way crops use nutrients as well as the source, time, rate, and method of application are imperative for nutrient management and optimizing crop production.


Source: AgroNigeria

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