Organic vs Inorganic Fertilizer: Pros, Cons [and More]


It’s a familiar story: we know organic and inorganic fertilizers but – talk about artificial, natural, synthetic, and chemical fertilizers and we’re a bit lost. Are they the same? No, not at all.

The pros and cons of using organic vs inorganic fertilizer include (1) variable vs precise nutrition content, (2) immediate and short-term vs gradual and long-term nutrition absorption by plants, (3) effects on the soil and the environment, and (4) fit to your production and application goals, to mention a few.

What Are the Main Types of Fertilizers?

Just for us to be on the same page, here’s a shortlist of how we usually categorize fertilizers:

ClassificationsDescriptions
Organic fertilizersOrganic fertilizers are made when microbes decompose plant parts (e.g., ash, moss, bark, compost, grass clippings, crop residues, etc.) or animal waste (e.g., manure, urine, hair, dung, eggshells, guano, earthworm castings, etc.).
Inorganic fertilizersInorganic fertilizers are made from minerals from clay, rocks, or sand. Most are synthesized with chemicals.
Natural fertilizersNatural fertilizers are made through natural processes such as decomposition, evaporation, and or fermentation. Organic fertilizers are natural.
Synthetic fertilizersSynthetic fertilizers are made when chemical elements such as calcium, nitrogen, phosphorus, potassium, magnesium are synthesized with inorganic elements such as petroleum industry by-products.
Chemical fertilizersThese are fertilizers created with nitrogen, phosphate, potassium, or other chemicals. Synthetic and chemical fertilizers are artificial types.
Nine Fertilizer Classifications

FACTOID: Don’t be confused. Highly processed products that are based on compost or manure are also called organic or bio-fertilizers.

RELATED VIDEO: Organic fertilizer VS Chemical fertilizer (2:12 minutes)

What are the Qualities of a Good Fertilizer?

It’s very important to fertilize soil regularly, particularly when plants are spaced close to each other in small spaces such as planters, pots, or window boxes.

It’s even more important when water leaches crop soil or previous crops deplete the soil of its nutrients. In either case, choose a good fertilizer with at least seven elements:

Non-toxicFertilizer should not contain any toxic elements that can cause direct or indirect harm to humans, plants, the soil, and / or the environment.
SolubleFertilizers with elements that are soluble in water allows plants faster absorption and better distribution of and management of fertilizer nutrients.
Contains 6 macronutrientsThe 6 macronutrients for plant health and productivity are nitrogen (N), phosphorus (P), potassium (K), as well as calcium (Ca), magnesium (Mg) and sulphur (S).
Contains 11 micronutrientsYour plants need micronutrients such as boron (B), chlorine (Cl), cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), nickel (Ni), silicon (Si), sodium (Na), and zinc (Zn).
Protects plantsFertilizers that help plants resist or tolerate pests and diseases reduce the use of toxic pesticides and herbicides.
Improves the soilGood fertilizers contain absorbent and organic materials such as worm casings, perlite, and coco fibers to improve soil texture, oxygen content, and drainage.
Promotes 3 key soil elementsPlants need the three key soil elements of carbon (C), hydrogen (H), and oxygen (O) for photosynthesis, for creating carbohydrate structures, for generating hydrogen from water, and for creating carbon and oxygen from carbon dioxide in the air.
The 7 Elements of Good Fertilizers

PRO TIP: Always store fertilizers away from the reach of children, the disabled, and all farm or domestic animals.

FREE PDF: Fertilizer and plant nutrition guide (190 pages) FAO United Nations

What are Organic Fertilizers?

Organic fertilizers are created by microorganisms to decompose plant and animal sources and create nutrients that remain in their natural forms. Here are some examples:

TypesDescriptions
CompostIt is rich in nitrogen that is formed by decomposing vegetable matter
Composted dungIt is well-balanced and, unlike fresh dung, does not require any pre-composting.
ManureCows, sheep, poultry, and horses are nature sources of garden manure. It has lots of organic matter but low in nutrients.PRO TIP: To avoid plant shock or death, never use fresh manure.
GuanoBat guano fertilizer is usually in powder form and is rich in soluble trace elements as well as nitrogen and phosphorus.PRO TIP: Diluted bat guano can be sprayed on leaves or on topsoil.
Blood mealThis is blood from animal slaughter that is dried and finely ground into powder to create a fertilizer rich in nitrogen, calcium, phosphate, and trace elements.PRO TIP: For strong roots, leafy greens, and flowering, mix to soil before planting.
H&H mealCattle hoof and horn from slaughterhouses is roasted, ground, and dehydrated to create an organic fertilizer with very high organic nitrogen content and has a very slow decomposition rate.PRO TIP: This can be used to introduce microorganisms in the soil.
Mustard seed meal or cakeMustard seeds are made into cakes, which is then crushed into powder for an organic fertilizer that can be mixed with soil to promote plant growth and flowering.
Spinach, peanutsSpinach and peanuts are natural fertilizers that capture nitrogen from the air to enrich the soil. When harvesting, cut at soil level and leave the roots in the ground.
Typology of Organic Fertilizer Content

PRO TIP: Local sources of information about organic fertilizers are livestock operators, farmers, and greenhouse owners. You can also visit cattle feedlots, dairy farms, poultry farms, and hog farms.

FACTOID: At least 8,000 years ago, humans were already using fertilizers to grow their food crops. However, the first modern fertilizer was created only about 100 years ago.

What are Examples of Organic Fertilizers?

Although organic fertilizers are produced in commercial quantities and are available online, they include biodegradable elements that support best green practices. The most common are in the form of cake, emulsion (here go check a good on Amazon), extracts, gels (the general organic here on Amazon is a good brand), granules, liquids (here one quite used by many), powder, pellets, spikes.

FREE PDF: Combined use of chemical and organic fertilizers (9 pages)

What are the Pros and Cons of Organic Fertilizers?

The best sources of information are actual fertilizer users. While some of them might name specific brand names of fertilizer products they’ve used, most would share context-specific advantages and disadvantages they’ve experienced.

Here’s what they know about the pros and cons of organic and natural fertilizers.

Organic Fertilizer

Among the most common: Manure,Compost,Mulch,Worm castings.

Pros

Gradual intake: The slow release of nutrients allows plants to absorb them with no stress on plant roots.

Low cost: Home composting is free. You can even get them free from farms, dairies, and so on.

Neutralizes soil acidity: Improves buffering capacity against fluctuations in pH levels.

Plant health: Carbon and other minerals feed microbes and fungi as well as introduce essential microorganisms that create nutrients that plants need.

Safe: Biodegradable, sustainable, environmentally friendly and can be used in areas with pets, children, or food crops.

Soil health: The organic content enhances the soil structure and improves humidity flow.

Cons

Expensive: Organic fertilizers cost more due to long, complex processing, plus costs for packaging, transport, and storage. Expensive when used on a large scale.

Inconsistent: Natural nutrient ratios are lower and inconsistent. Less nutrient concentrations than synthetics.

Scorching: Excessive nitrogen in blood meal or manure can cause salt burns in plants.

Slow:Nutrient intake and absorption from roots to stems, leaves, flowers and fruits can last from 12 days up to 12 weeks.

Tiring: Dry organic fertilizers must be worked into the soil. This is time-consuming and physically tiring for large-scale use.

Variables: The right mix of microorganisms, warmth and moisture are required to release nutrients for plant absorption.

Naturally Sourced Fertilizers 

Among the most common: Limestone, Rock phosphate, Rock dust, Green sand, etc.

Pros

Enrichments: Includes trace elements essential to soil structure and plant growth.

High nutrient ratios: Provides high degrees of concentrations of particular elements.

Pro-microbial: Provides support to fungi, microbes, and other beneficial bio-organisms.

Plant health: Slow release of nutrients prevent root stress through natural intake speed.

Cons

Large carbon footprint: Components are mined which requires complex equipment and several processes.

Non-renewable: Contains limited resources that are mined from the earth.

Variability: Minerals from different sources have different base compositions or components.

FREE PDF: Secrets of the Soil (225 pages)

What are Synthetic Fertilizers?

Synthetic fertilizers are synthesized from rock salts or petroleum by-products while chemical fertilizers are from ammonia, nitrogen, phosphate, etc. Artificial fertilizers include both synthetic and chemical types and are produced in different forms:

Liquid

Here what you need to remember about liquid ones:

  • Of all the synthetic fertilizer forms, liquid products are preferred for use in most high-value areas and applications such as front lawns, golf courses, and designer greeneries.
  • Liquid fertilizers allow ease and speed of application and quick results for better productivity as well as for immediate correction of nutrient deficiencies in plants, crops, and other vegetation
  • However, expect higher costs than dry fertilizers as well as more capital requirements for production, packaging, transport, storage, and application.

Dry

Here some key points of dry fertilizers:

  • Dry synthetic fertilizers are the easiest to mass-produce into various forms. Uniform nutrient distribution means that each particle has all NPK nutrients.
  • Since nutrients do not segregate during fertilizer packaging, handling or spreading, there is less risk of issues such as spotty growth, non-uniform color, or other crop issues.
  • Dry fertilizers require water to dissolve nutrients for plant absorption.
  • Over-fertilization and toxic buildup are common concerns.

Gas

  • NPK macronutrients and micronutrients in gas form in soil or potting mediums are naturally-occurring food sources for plants.
  • When fertilizers in gaseous form are injected into the soil, there is immediate absorption through the roots of plants.
  • However, due to inherent dangers in the gaseous form, there is no production in commercial quantities.

Gel

  • Gel fertilizer (or suspension) products are semi-solid synthetic products that contain all NPK nutrients embedded in gel particulates that range from strong to weak gels. These are soluble in water.
  • Gel fertilizers release nutrients gently and work best when used as foliar applications.
  • Gel concentrates are cheaper in that they can be dissolved in water to give you higher nutrient ratios per liter.
  • However, due to specific production and packaging requirements, there are less (and pricier) choices on the market compared to dry and liquid forms.

FREE PDF: Synthetic Fertilizer Application (3 pages)

What are Examples of Artificial Fertilizers?

Synthetic or chemical fertilizers are also called artificial fertilisers simply because they’re made by using artificial processes, machinery, and equipment. Yes, you got that right: Synthetics are not made in nature but in laboratories.

Here some example synthetic fertilizers

  • Nitrogen: this pure nitrogen as the on Amazon
  • Phosphorus: Areo Garden Liquid on Amazon
  • Ammonium sulfate: here a good brank on Amazon
  • Ammonium phosphate: here an example
  • Ammonium nitrate
  • Ammonium chloride
  • Sodium nitrate
  • Urea: like this one on Amazon

FREE PDF: All about fertilizers (30 pages)

What are the Pros and Cons of Synthetic Fertilizers?

One of the strongest arguments for synthetic fertilizers is that they can be produced quickly at lower cost and in large volumes to allow more planters, farmers, and gardeners more solutions to their plant and soil issues.

Here’s a summary of the most commonly-cited advantages and disadvantages of synthetic and chemical fertilizers.

Synthetic or Chemical Fertilizers

Here the pros and cons of chemical and synthetic fertlizers are summed up:

Pros

Variety: Dry synthetic fertilizers are sold as concentrated powders, granules, pellets or chips that can be diluted with solids or liquids for strength control.

Efficiency: You can buy synthetic fertilizers in any quantity, so they’re easy to use and more efficient and convenient for all gardeners and farmers.

Speed: Synthetic fertilizers can release nutrients faster and cheaper than organic fertilizers.

Consistency: Their nutrient and chemical content are clearly stated on labels. Best choice if you want to correct soil pH balance quickly.

Faster effects: Synthetic fertilizers provide highly concentrated nutrients that act immediately and without microorganisms.

Precise application: You can choose the specific ratios of nutrients even to large areas

Cost: Chemical fertilizers cost less and are cheaper to produce than natural fertilizers sold on the market.

Cons

Toxic processing: The repeated use of more water and chemicals (arsenic, cadmium, uranium) creates toxic buildups that can harm the planet and everyone in it.

Fertilizer burns: This happens when nutrients are released too rapidly into the soil. Over-fertilization can upset soil ecology and pH balance.

Contamination: Adding more fertilizer leaches toxic chemicals into other areas, pollutes water sources, and harms living things.

Soil degradation: Necessarilyrepeated and long-term use as well as lack oforganic matter can a) deplete soil nutrients, b) kill off essential microbe ecosystems, and c) release greenhouse gases.

Not sustainable: Chemical fertilizer is made of unsustainable petroleum products that pollute the earth. Manufacturing also uses up enormous amounts of energy.

Added expenses: Since crops grow better, weeds do too, and more insects are attracted. Be ready to spend more on herbicides and pesticides.

FREE PDF: Soil pH and Fertilizers (2 pages)

And there you have it – everything you need to know about fertilizers organic, inorganic, and more.

But, wait!

Before you go, here are four essential takeaways from this article.

Key Takeaways

  1. What are you feeding? Do you intend to feed the soil or the plant?
  • Feed the plant: Use synthetic or inorganic fertilizers to feed the plant with nutrients.
  • Feed the soil: Use organic or natural fertilizers to feed the soil with organic matter that introduces nutrients and micro-organisms that, in turn, create plant nutrients.

Synthetic vs organic: Choose your fertilizer form and content according to what your plant or soil needs:

  • Production priorities: Go for synthetic fertilizer if you’re a commercial grower focusing on profit, efficiency, productivity, and deadlines.
  • Green priorities: Go for organic fertilizer if your top priorities are green practices, health and safety.
  1. Constant vs variable needs: Are you addressing constant or changing plant needs?
  • Constant needs: Your plants feed all the time, not just in the daytime, not just when you’re awake, and not just when you’re fertilizing or watering the soil.
  • Changing needs: Herbs grown indoors and plants have needs that change with the seasons, the weather, pest attacks, and so on..

Choosing the right fertilizer: There are five points to keep in mind when choosing fertilizer:

  • What your plants need: If your plants need immediate nutrient feeding, use liquid organic fertilizer via foliar spray. For longer-time nutrition feeding, use organic, slow-release gel or pellet fertilizer.
  • What your soil needs: To quickly enrich poor or depleted soil, fertigate at driplines. To dry soil, add manure fertilizer or add sand. For anaerobic soil, add mulch or compost.
  • What your fertilizer provides: Choose fertilizer with the right NPK ratios. For speed and efficiency, use commercial fertilizer. For non-toxic products and environments, use natural, organic fertilizers.
  • What your budget allows: If you have more time and little money, find local sources of organic, natural fertilizer from cattle feedlots, poultry farmers, and as for free manure or plant and crop waste. If you have more money and little time, buy commercial fertilizer.
  • What your time allows: If you have time for messy DIY tries, make your own fertilizer. If you have short growing seasons, must meet deadlines or profit margins, go for synthetic commercial fertilizers.

And there you have it – everything you need about choosing between organic and synthetic fertilizers.

Happy planting!

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Andrea

A young Italian guy with a passion for growing edible herbs. After moving to the UK 6 years ago in a tiny flat, it was impossible to grow herbs outside. So I start my journey in growing indoor and so I decided to share my knowledge.

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