Fertilizer is defined as any organic or inorganic element of natural or synthetic origin which is added to the soil to provide one or more plant nutrients required for plant development.

By Rehan Jameel, Muhammad Anjum Zia, Athar Mahmood and Maria Naqve

Naturally occurring nutrients are not always accessible in the forms or quantities required by plants. Fertilizers are applied to enhance the soils nutritional status and quality by supplementing it with nutrients. To sustain proper physiological function of the cell, crop plants require nitrogen, phosphorus, and potassium. Fertilizers include all of the elements required by plants to reproduce, and they are applied to the soil to improve its physical, biological, and chemical characteristics. It has been observed that farmers apply both organic and inorganic fertilizer for improving crop production and maintain fertility. Fertilizers are needed and applied to restore nutrients depleted from the soil during crop harvest, and they are also used to supplement extra nutrients in order to increase crop production.

Plants needs vital nutrients such as nitrogen (N), phosphorus (P), potassium (K), and many other minerals for development and obtain them from soil. The nitrogen-phosphate interaction is critical and has a direct influence on soil performance. NPK fertilizers are added to soil to increase yield, however they are not entirely used by crops.

Synthetic fertilizers:

Synthetic fertilizers are extensively used in agriculture. Synthetic fertilizers was firstly used at the end of nineteenth century and made revolution to modern agricultural production. Their use increases crop yield and show revolution in the field of agriculture that world had not seen before. They immediately act on soil and easily available to plants unlike organic fertilizers which firstly need to break down and then absorbed. There are also some negative effects of synthetic fertilizers.

Disadvantages of Synthetic fertilizers:

Synthetic fertilizers reduce the nutritional value of crops. Excessive use of synthetic fertilizers causes toxicity in soil. They kill the beneficial microorganisms present in the soil that decomposes human and plant dead bodies into organic matter which is rich in nutrients. A natural balance is found between healthy soil containing microbes and plant health. When synthetic fertilizers added to soil this balance gets disturbance which ultimately affects plants and environment. NPK based fertilizers reaches underground water and cause water pollution. When these fertilizers drain in lakes, rivers and streams affect water bodies and disrupt aquatic ecosystem. Plants grown in excessively fertilized soil lacks iron, protein, vitamin C, copper and zinc. These three elements, when supplied synthetically, have a significant negative impact on how plants absorb other essential mineral elements. These are only 3 of the 13 fundamental components, although there are many more. It is not a healthy, well-balanced diet for plants.

Nitrites levels are increased by synthetic fertilizers. These nitrites interact with hemoglobin present in blood vessels, which affect the respiratory and vascular system causing suffocation and leading to death in severe cases. Metals found in synthetic fertilizers are known to be carcinogens, reproductive, liver and blood toxicants. According to EPAs (Environmental Protection Agency) office of pesticide program, inorganic fertilizers are the major cause of human carcinogens chemicals which causes cancer. The improper use of synthetic fertilizers can produce nutritional imbalances, limiting the absorption of other important nutrients and causing soil acidity, resulting in reduced crop yields. The person having any kind of urinary or liver problem or allergy should avoid any type of exposure to synthetic fertilizers.

Organic fertilizers:

Fertilizers made from living or biological matter. Organic fertilizers are carbon-containing fertilizers that are synthesized naturally. These fertilizers require more time to break down in soil and release nutrients. Bio fertilizers are considerably more preferred now days as they are alternative of synthetic fertilizers and have no negative effect on environment and human health. Organic fertilizers are available in various forms such as:

  • Manure from livestock such as cows, chicken, goats etc.
  • Green manure derived from plants, usually various types of legumes.
  • Compost comes from agricultural waste that is organic waste such as straw, maize stalks, or decomposed trash.

Advantages of organic fertilizers:

Organic farming is one of the fastest developing industries throughout the world with the primary goal of creating a balance between interconnected systems such as soil microorganisms, plants, animals and humans. Like synthetic fertilizers organic fertilizers improve quality and production of crops hence it does not pollute environment. They increase the activity of microorganisms present in soil and fix nutrients for plants availability. Organic fertilizers delivers nitrogen in suitable form, which easily uptake by plants and helps in plants development while not causing root burning or killing important microorganisms in soil. Organic fertilizers increase plant tolerance and prevent disease by meeting the nutritional needs of plants. This step eliminates major source of stress. Organic fertilizers slowly but continuously release nitrogen and other nutrients and prevent leaf and root burning.

The annual production of biofertilizer is estimated about 7000 tones from almost 70 units, with an expected consumption of biofertilizers around 6000 tones. Biofertilizers are substitute of traditional fertilizers since they are less expensive than synthetic fertilizers and can be generated in large amounts on the farm, making them economically advantageous to farmers. Some common microbial inoculants such as Azotobacter, Azospirillum, Rhizobium and blue-green algae are good nitrogen fixer while Aspergillus awamori, Bacillus megathrium var phosphaticum and Penicillium digitatum etc are effective phosphate solubilizer. Because of the use of many nitrogen-fixing bacteria and cyanobacteria, biofertilizers are also known as “Microbial inoculants.” Biofertilizers contain 75% moisture and can be directly applied to the field. The nitrogen content in biofertilizer is 3.5-4%, phosphorus content is 2-2.5% and potassium is 1.5%.