Fertilizer Practices: What are the Types of Fertilizer?

What are fertilisers?

Fertilizers are the plants’ food and are usually derived from the soil they grow in. Hence, the overarching goal of fertilizers is to restore or add the required nutrients needed for plants to continue their development. As the plants grow and nutrients are absorbed from the soil, their levels in the ground need to be monitored and restored to avoid depletion. Nutrients can be made out of organic or artificial materials and contain one or several different kinds, depending on their use case. Fertilizers and the corresponding nutrients they provide the plant with are fundamental for maintaining and enabling its physiological properties. 

Besides their nutrient component, fertilizers can come in liquid, granular or even gaseous form. Each has its perks and specific use cases. Manure is an example of liquid fertilizer. After it has been collected from livestock, it is spread into the field via a specialised liquid fertilizer distribution machine or an irrigation system using sprinklers. In the case of manure, it can also be applied when in a more solid format. Using a solid-manure spreader, it is distributed on the field by shredding it. Compared to other fertilizers and application methods, solid manure is limiting as it rarely can be done during the growing season. 

Granular or pellet fertilizers vary in size and can be applied more freely at any time during the growing season. This is especially helpful when a farmer chooses to fertilize in combination with seeding and can do so without damaging the seeds. Furthermore, using granular fertilizer brings about additional flexibility. With different equipment available and based on the crop’s needs, farmers can choose to spread over the crops but in specific rows next to it, e.g. for potatoes. 

Anhydrous ammonia, a combination of nitrogen and hydrogen, is an example of both a liquid and gaseous fertilizer. When pressurised, it is a liquid and also stored as such. However, when the pressure is released and under atmospheric pressure, it turns into a gas. Therefore, anhydrous ammonia is applied to the field in a gas form by injecting into the soil 13-15 cm deep using a pipe.

What are the most critical nutrients?

1. Nitrogen

Nitrogen is of the three essential nutrients and required for the crops metabolic functions. It plays a vital role in almost all processes in the plant, from building protein to facilitating chlorophyll. How? Nitrogen helps the plant to build important structures such as nucleic acids and proteins. The quality and amount of protein found in the crop is a key metric farmers need to measure. Depending on the crops end use (e.g. human consumption, processed for alcohol) certain standars need to be met. Farmers get paid more for better quality crops.

2. Phosphorus

Phosphorous is the second of the three most critical nutrients. Therefore, maintaining the correct phosphorous levels is a primary concern of farmers at the beginning of the growing season as it promotes root development. Later in the growing season Throughout the plants life phosphorous is key in allowing the plant to store energy and its transfer across cell membranes. Phosphorous also helps to maintain the plants membrane structure. 

3. Potassium

Potassium is the final of the essential nutrients. It, too, serves many functions especially in successful enzyme activation. It also plays an important role in photosynthesis for example through transpiration. Potassium also allows plants to store water during warm weather conditions such as drought. With the correct amounts of potassium, plants also become increasingly resilient to pests.  among which are water retention and increased resilience to pests.

4. Boron

Boron enables the vital function of cell wall synthesis which allows plan cells to expand. Without the correct levels of boron plant growth is stunned. Root development and pollen production are also reduced. Such a deficiency is also visible on the leaves which become deformed. Ultimately a lack of boron leads to a lower quality harvest.

5. Sulfur

Sulfur too helps plants effectively fight diseases. It also aids in the process of photosynthesis by helping to produce the amino acids chlorophyll production. 

6. Calcium

Calcium helps to maintain the plant’s membranes and survive environmental extremes such as drought. 

7. Magnesium

Magnesium enables plants to continue their growth and development even in high temperatures, which otherwise would have slowed it down.

What about other micronutrients?

Plants contain many other elements such as sodium, iodine and silicon. These have, however, not been found to contribute essentially or significantly to the plant’s health. 

Human Nutrition

Proper human nutrition is not only dependent on yield alone. Healthy and well-developed crops are needed. Hence, maintaining the correct levels of nutrients in the soil, which gets absorbed by the plants, directly impacts us. By keeping healthy crops through fertilization, we get our daily calories, vitamins, proteins, fibre and minerals. Though we have become increasingly better at producing more better quality crops through fertilization, we need to become better at scaling. The worlds agricultural outputs need to grow by 60% to meet the demands of the global population in 2050. In our fight for a greener future and freedom from hunger, fertilizers are the key. Sustainably applying fertilizers allows us to grow more food at a better quality for an increasing population without requiring more land.

In our upcoming blog series Fertilizer Practices, we will deep-dive into the world of fertilizers and how they enable the lives of over 3 billion people today.