Organic vs. Inorganic Fertilizer – A Comparison

Keeping your garden and lawn fed is an essential part of a beautiful lawn. But what kind of fertilizer should you use — organic or inorganic? What’s the difference? And what does it mean for your lawn?

What is organic fertilizer?

Organic fertilizer is made from organic material broken down or is biodegraded by beneficial microbiology to make nutrients available to your plants.

Organic fertilizers include compost, livestock manure, vermicompost, kelp, bone meal, blood meal, alfalfa meal, and more.

Organic fertilizer is not the same as certified organic, a certification process that farmers and other companies undergo to ensure their products follow national guidelines.

Organic vs. Inorganic Fertilizer - A Comparison

Organic fertilizer may be certified organic, but it isn’t always. Your backyard compost or vermicompost is still considered organic fertilizer.

Want to learn more about making compost? We’ve got a guide for that!

What is inorganic fertilizer?

Also known as chemical or synthetic fertilizers, inorganic fertilizers are manufactured using synthesized chemicals.

While the specific ingredients in inorganic fertilizer depend on the manufacturer, it could include ammonium hydroxide, urea, ammonium nitrate, phosphoric acid, and potassium hydroxide. Many of these ingredients are actually in salt form.

Inorganic fertilizers come in different formulations of NPK (nitrogen, phosphorus, and potassium) and can be quick-release or slow-release, liquid or granules or spikes.

Organic vs. inorganic fertilizer — which is better?

Which is better for nutrients?

Lab studies have shown that plants themselves can’t tell the difference between nutrients from inorganic fertilizers or organic. But that’s not the complete picture.

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Inorganic fertilizers come with higher concentrations of the 3 main macronutrients: nitrogen, phosphorus, and potassium (NPK). Manufacturers design them to give your lawn or garden a quick boost. But these concentrations come with 2 downsides:

  1. High concentrations of nitrogen will cause nitrogen burn if improperly applied, which can kill your plants, and
  2. While some formulas may come with added iron and calcium, they’re missing 13 micronutrients that your plants need to grow and thrive.

Organic fertilizers come with lower concentrations of NPK, but they’re also full of 13 other micronutrients. While you don’t get the artificially dark green grass of a spike of nitrogen, you get healthier plants overall, and you’re rarely in danger of applying too much nitrogen.

Organic vs. Inorganic Fertilizer - A Comparison

Think about your diet. You could technically survive on just carbohydrates, proteins, and fats. Still, you’re going to be unenergetic, pale, and likely to come down with every cold and flu you come across as your immune system is compromised. But when your diet is full of minerals and vitamins, you’re full of energy, your skin glows, and your immune system fights off most infections.

It’s the same with plants. They need more than just NPK to grow healthy and fight off pests and disease.

A wide variety of micronutrients is essential when growing vegetables. If all your vegetables get is NPK, and whatever leftover micronutrients linger in the soil, then your vegetables will not be full of iron or calcium or other healthy human micronutrients.

Some argue that some organic fertilizers (especially homemade ones) have varying and unpredictable amounts of nutrients, so you can’t possibly provide your plants all the nutrition they need.

Synthetic fertilizers tell you exactly what ratios NPK is. But the truth is, most of us don’t need to be that precise. Just keep an eye out for signs of nutrient deficiency and add the appropriate amendments when required. It’ll be fine.

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And if you’re anxious, get the soil test done on your compost pile when you submit soil samples for the rest of your lawn.

(You need to be precise with synthetic fertilizers, as too much will kill your plants.)

Which are better for the soil?

Plants may not be able to tell the difference between organic and inorganic fertilizers, but the soil definitely can.

Synthetic nitrogen decimates the diversity of beneficial microorganisms in the soil that would otherwise break down organic matter into nutrients to support your plants.

Inorganic fertilizer also cuts down on the amount of organic matter in the soil, which means more erosion and more compaction.

Organic vs. Inorganic Fertilizer - A Comparison

Organic fertilizers, especially composts, add organic matter into the soil and support beneficial microorganisms, supporting your plants and lawn. They create loamy, aerated soil that’s a pleasure to garden in.

What are the costs of organic vs. inorganic fertilizer?

You may think that organic fertilizer is way more expensive than inorganic since organic products like vegetables cost more than non-organic.

But you can make compost in your backyard for free or buy a bag for $10. Other organic fertilizers can be more expensive, like fish emulsion.

According to Fixr, it costs between $50 – $95 to have a lawn care company apply organic fertilizer or $25 – $80 to apply inorganic. The price depends on the type of inorganic fertilizer.

However, since you only need to apply organic fertilizers once a year, but you need to use inorganic fertilizers multiple times, you’ll save more time and money by going organic.

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If you have a large lawn or need a lot of fertilizer for your garden, look for bulk compost in your local area. You can get compost much cheaper per pound in bulk than by buying bags.

Bags are better if you only need a small amount. Or make your using yard and kitchen scraps for free.

What are the environmental impacts of organic vs. inorganic?

Organic fertilizer typically positively impact salt types of the environment, supporting the food web in your soil and reusing kitchen and yard scraps instead of sending them to the garbage dump. In contrast, inorganic has a negative impact, to say the very least.

Inorganic fertilizers:

  • Destroy the beneficial microbiology food web in your soil, meaning you have to apply more and more fertilizer to get the same results, and increases erosion and soil compaction.
Organic vs. Inorganic Fertilizer - A Comparison
  • Leech quickly from the soil, ending up in wildlife preserves, local waterways where they cause algae blooms and kill fish.
  • Increase the risk of developing cancer in humans and cause Blue Baby syndrome, a fatal illness, when they end up in groundwater and drinking water. Always wear a mask and protective clothing when applying synthetic fertilizers.
  • Cause salt-buildup in the soil, as most of the components are salt types, especially when there’s little rain.
  • Add greenhouse gases, and nitrates are just as harmful as carbon dioxide.

Environmental Protection goes more into the dangers of using chemical fertilizers.

This video presents the properties, advantages, and disadvantages of organic and synthetic fertilizers:

Conclusion

Using inorganic fertilizers comes with a lot of downsides, especially in the long-term. Whenever possible, use organic fertilizer. Your garden, lawn, and soil will thank you for it.

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Jill Sandy

I am a sustainable focus gardener. I love decorating my home backyard with beautiful landscape design and creative garden care techniques I develop myself.