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Types of Fertilizers: A Detailed Overview

Published:

November 15, 2024

Key Takeaways:

The two key types of fertilizers are organic and inorganic, each with specific reasons for use, the speed of components’ release, and the way of application.
The main nutrient-focused fertilizers include nitrogen-based, phosphorus-based, potassium-based, and multi-nutrient containing all three.
With the help of modern technology, it becomes easier to define when the plants need particular fertilizers and choose the most appropriate time for applying them.

Even the most natural, organic farm needs to add some agricultural fertilizers now and then. Plants need their nutrients to grow well, and it's impossible to maintain perfect soil content without additional efforts from the farmer’s side. From giving plants a mid-growth boost to ensuring your soil is healthy enough for the next season, fertilizers are a major part of operations at farms of all sizes.

However, fertilizer should be used as a precision tool: only using as much as necessary, and picking the right type to match your needs at the moment. So in this article, we'll look at your options in fertilizer for crops, and how to select the right product depending on your needs.

Organic vs Inorganic Fertilizers

One of the most basic choices is whether to use organic or synthetic fertilizers. Organic fertilizers are made directly from natural materials, such as manure or animal byproducts like fish meal. Synthetic options are manufactured in laboratories to concentrate nutrients into economical packages.

We've written on the topic of organic vs inorganic fertilizers before, so here we'll keep this short.

Synthetic fertilizers are powerful and fast-acting. They're also generally cheaper to obtain and utilize. However, they require caution because their overuse can wreck the soil's biological components. Too much nitrogen at once, for example, can scorch plants' stems and roots. In addition, synthetic fertilizers can potentially lead to runoff and cause environmental issues.

Organic fertilizers are bulkier and slower-acting, typically used for measured nutrient replenishment over the course of a season. They're also usually more expensive to use. However, they are far better for your soil health and for the environment in general. In the long term, a farm will be healthier if it sticks to organic fertilizers.

Best practices are typically to rely on organic fertilizers as much as possible, while using synthetic fertilizer sparingly as needed.

Nutrient-Focused Fertilizers

Regardless of whether they're organic or synthetic, most fertilizers used in agriculture are focused on delivering the very specific nutrients your plants need to thrive.

The most important nutrients that nearly all crops need are nitrogen (N), phosphorus (P), and potassium (K), or NPK. So, typically, a fertilizer will focus on delivering one or all of these core nutrients.

Nitrogen-Based Fertilizers

Nitrogen is key for plants' proper growth, as it is necessary for them to produce the chlorophyll which converts sunlight into energy. Nitrogen also contributes protein to plants and supports their amino acids. So, nitrogen fertilizers are usually a go-to solution for helping crops perk up if they're growing too slowly or showing signs of being stunted.

Typically, nitrogen-specific fertilizers are synthetic, including popular options such as ammonium nitrate (nitric acid), and calcium ammonium nitrate. A more organic option is to use urea ammonium nitrate, which is based on one of the main ingredients in urine — another good source of nitrogen.

It's also worth mentioning that legumes such as peanuts and soybeans can fix their own nitrogen from the atmosphere, and will actually contribute nitrogen to the soil as a result. Rotating nitrogen-hungry crops with legumes across seasons can help maintain nitrogen levels with a reduced need for fertilizers.

Phosphorus-Based Fertilizers

Phosphorus contributes to the health of plants' roots and stems, as well as assists with flowering, seeds, and fruit creation. So it's a necessity for most crops intended for food.

Phosphorus fertilizers are typically formulated to be slow-release, spread on a field before planting so that they can support the crops throughout their life cycle. Most commonly, water-soluble options are used, such as calcium superphosphate or triple superphosphate.

In cases where crops need extra phosphorus mid-cycle, nitrophosphate is often used. This can be applied infrequently, as needed, rather than being spread before planting.

Potassium-Based Fertilizers

Potassium is used by plants in a wide variety of ways. It improves root health, activates enzymes, aids in photosynthesis, and more. Its multipurpose nature means that plants will often rely on potassium as a backup nutrient if they're lacking nitrogen or phosphorus.

Potash, or mixtures including it, is the most common source of potassium fertilizer for plants. Potassium chloride, aka muriate of potash, is a frequent go-to option for adding potassium to a field when needed. It's particularly effective with tall-growing grains such as corn, rice, or wheat.

For smaller crops, or those growing in dry fields, potassium sulfate can also be used.

Multi-Nutrient Fertilizers (NPK)

Finally, there are compound fertilizers that include all three major nutrients. A wide variety of formulations are available, to fit the needs of any given field. However, it's typical for them to deliver equal amounts of all three nutrients to promote all-around soil health.

These fertilizers are almost exclusively synthetic, and typically intended to be spread before planting.

Specialty Fertilizers

There are more specialized fertilizers available, for particular cases. These include:

Micronutrients. Besides NPK, small quantities of other minerals are needed for plant growth. This includes sulfur, magnesium, calcium, iron, zinc, copper, and even boron. Typically, these are folded into other compound fertilizers, but occasionally may need to be added directly if there's a deficiency.
Slow-release. As opposed to organic fertilizers like manure which are naturally slow-release, some synthetic fertilizers are coated in resins or polymers to slow their release over time. This can be useful during times of drought or other difficult planting situations.
Spikes and tablets. Fertilizers can be delivered as spikes or tablets, stuck directly in the ground for a different form of slow-release at the root level. These are convenient as fertilizers used by farmers on smaller plots, but most commercial operations will use more direct fertilizing methods.
Liquid fertilizers are fast-acting and often used as quick pick-ups. However, they're also vulnerable to evaporation and runoff, so they should only be used during times of moderate sun and rain.
Foliar fertilizer is applied directly to the leaves, rather than the soil or roots. Most often, these are used to stimulate flower or fruit/seed growth in plants that are struggling to mature on their own. Care must be used: much like nitrogen, overuse of foliar fertilizers can scorch plants and harm them, and sometimes, inorganic foliar fertilizers may decrease nutrient absorption.

When you have questions, we'll help you find the answers you need to take control of your fields and the harvest you care about. Contact Cropler to discover more about our products and the ways we help you proactively protect your operations from the effects of crop diseases. Learn More

Choosing the Right Fertilizer for Your Plants

Efficient farming which can support the growing human population, while remaining ecologically sustainable, is a major issue facing modern farmers. It's vital to carefully consider the needs of your plants in the short term, as well as think about the overall long-term health of your land.

Frequent soil testing is a must. You need to keep close tabs on the nutrient content of the soil and keep it balanced. In addition, you should know the specific ratios of NPK your crops need. For example, leafy greens are hungry for nitrogen, while flowering plants need more phosphorus.

And always consider the environmental impact. As we said before, consider a combined approach for higher effectiveness: stick to natural fertilizers and crop rotation as much as possible and use synthetic fertilizers only when necessary. Overuse of synthetic fertilizers is a quick-fix solution but it can cause bigger long-term problems for your soil health.

Cropler can help! Our revolutionary smart farming products combine wireless weatherproofed agricultural cameras with an always-accessible online dashboard collecting data about your plants' health. If they're suffering from nutrient deficiency, you can see the signs more easily, and keep track of their health and environmental conditions over many seasons to improve fertilizing efficiency.