Liquid vs Granular Fertilizer [Pros and Cons] With Science

Wouldn’t it be great if you can just quickly choose the best liquid or granulated fertilizer? Unfortunately, there are so many fertilizer types, elements, and factors to consider that choosing one can be rather, well… daunting.

Liquid and granular fertilizers have different pros and cons to consider in terms of 1) your goals and limitations, 2) what your plants need, 3) what the soil lacks, as well as 4) the fertilizer type and nutrition content you should use for the best results.

Today, I’ll help you get to the bottom of it all and make choosing the right fertilizer much easier!

What are the Different Forms of Fertilizers?

The three main forms of fertilizer are 1) liquid, 2) dry, and 3) gas. In general, they differ in terms of speed of effect and method of application.

Few of us who use fertilizers actually know the key advantages and disadvantages of granular and liquid fertilizers. Of course, we know common generalizations such as these:

TypeDescription
Liquid FertilizerThese act faster than solid or granular fertilizers, and can be spread faster over larger areas such as farms and orchards.
Dry FertilizerThese are organic or synthetic fertilizers that are produced en mass but require water for the plant to efficiently absorb its nutrients.
Gas FertilizerThese are generally produced from natural gas such as methane which is processed to form nitrogen fertilizer.
Difference Between Liquid, Dry, and Gas Fertilizers
What is Better? Liquid vs Dry Fertilizer

What are the Subtypes of Dry Fertilizers?

Subtypes of granular fertilizers include 1) cakes, 2) granules, 3) manure, 4) mulch or compost, 5) pellets, 6) powders, 7) sludge, and 8) spikes, sticks, or stakes.

Whether organic or synthetic, dry fertilizer gives different benefits. Here’s a quick rundown of dry fertilizer forms.

Forms of Granular FertilizersDescription
CakesDIY as well as commercial fertilizers cakes are made to be ground or powdered for dilution and control. Examples are dung cake, oil cake, neem cake, mustard cake, sugarcane cake, and fermented cake fertilizer.
GranulesCommercial-grade fertilizers sold as concentrated dry granules are used for slow release. The granules are activated by water.
PRO TIP: To prevent fertilizer burn, always wash away with water any granules left on the leaves.
ManureAnimal feces, either raw or dried dung collected from animals have been used for centuries to fertilize crop soils. It can smell but is eco-friendly.
Mulch or compostOrganic fertilizer can be in the form of mulch (spread on topsoil) or compost (mixed into the soil) which is deteriorated bio-materials from plants or animals.
PelletsCommercial and DIY fertilizer is made in concentrated powder form for ease of sprinkling or mixing into soil or compost, as well as for water solubility in hydroponic or indoor use. Many manufacturers of powder fertilizer use synthetics such as phosphorus, calcium, magnesium, potassium, or silicon, or organics such as bone meal, fish, peat, neem seeds, or seaweed.
PowdersMunicipal sludge from community sewage can be collected, dried, treated, and ground into biosolid compost for easy application as soil fertilizer.
SludgeMunicipal sludge from community sewage can be collected, dried, treated, and ground into biosolid compost for easy application as a soil fertilizer.
Spikes, sticks, or stakesCommercial fertilizers in spike forms are designed for hammering into the ground and for slow nutrient release over 6 months. Before using, know how much fertilizer to use, and the type of fertilizer for specific plants.
Subtype of Dry Fertilizers

Spikes of fertilizers are particularly interesting in terms of application. You need to hammer the spikes into soft, damp topsoil along the dripline for nutrient distribution and root contact when watered.

How to install fertilizer spikes & how they work.

What Fertilizer Should You Use?

The fertilizer one should use depends on the needs of the plant they are planning to feed. Leafy vegetables and foliage plants require nitrogen-rich fertilizers while flowering and fruiting fertilizers need

Liquid Vs Granular Fertilizer – Infographic

While mother nature doesn’t do labels, fertilizer manufacturers are required by law to inform buyers exactly what goes into their products.

Thus, each package shows an NPK code: three numbers that indicate the proportion of elements in the fertilizer.

Nitrogen (N)
The first NPK number
Function: Nitrogen helps develop the parts of plants that you see aboveground, particularly the health of leaves.
Deficiency: Your plant lacks nitrogen when the leaves are smaller than normal and many of the leaves are turning yellow.
Example 1NPK 12.0.0: The fertilizer contains 12% nitrogen. 
NPK 0.1.1: The fertilizer has 0% nitrogen, 1% P, and 1% K.
Phosphorus (P)
The second NPK number
Function: Improves flowering, promotes seed formation, and induces the fruiting of plants.
Deficiency: Phosphorus deficiency is not easy to spot. Some plants show purplish stems or dark blue-green leaves.
Example 2NPK 1.9.1: The fertilizer has 1% N, 9% potash, and 1% K.
NPK 7.8.9: A 100-pound bag of fertilizer has 7 pounds of nitrate, 8 pounds of phosphate (phosphorus), 9 pounds of potash (potassium), and 76 pounds of filler (also called ballast).
Potassium (K)
The third NPK number
Function: Potassium makes plants resistant to pests and diseases as well as helps in root growth and development. It also facilitates the development of fruits.
Deficiency: Potassium deficiency is not easy to spot. Some plants show purplish stems or dark blue-green leaves.
Example 3NPK 12.10.20 fertilizer for tomato plants: One kilo includes 120 grams of N, 10 grams of P, and 20 grams of potassium.
NPK 10.10.10 or 5.5.5: This is a fertilizer that provides the same relative amount of nutrients, so which one you use doesn’t matter. What you must know is how much fertilizer you should use, and when.
Minuscule quantities of Calcium (Ca), Sulfur (S), Iron (Fe), and Magnesium (Mg) in the soil are secondary but are key elements for chlorophyll as well as for plant growth and development.Function: Potassium helps plants to develop buds, flowers to blossom, and fruits to grow0.
Deficiency: Potassium deficiency in plants shows as stunted, discolored, and curled leaves, weak stems, and small fruits.
Effects of Nutrient Application and Deficiency on Plants

PRO TIP: When buying fertilizer from bulk sellers, write the NPK formula on your containers. Also, remember: that formula shows the percentage by weight.

Other countries have fertilizers with NPKS in their labels where S stands for sulfur.

More info on this in our article on plant nutrients!
Know Your Fertilizer: What NPK really means

What is a Granular Fertilizer?

About 90% of fertilizers are dry. Powders, pellets, granules, or cakes are put into the soil, but most are dissolved in water and then diluted before fertigation.

What is a Granular Fertilizer?
What is a Granular Fertilizer?

What are the Advantages and Disadvantages of Granular Fertilizer?

Since it’s clear that the well-being of our plants lies entirely in our hands, choose your fertilizer only after you have considered these common arguments for and against dry or granulated fertilizers.

Advantages of Granular FertilizerDisadvantages of Granular Fertilizer
Blending: Can be blended into specific types of fertilizer analysis.

Application: Can be applied as broadcast or bands. With powders, there’s less chance of waste or spills.

Timing: Nutrients are available throughout the growing season

Cost: Cheaper when purchased in bulk. When ordering online, lighter weight means cheaper shipping.

Storage: Will not settle or salt out when stored for long periods.

Release control: Slow-release products (e.g., polymer-coated urea) available
Non-liquidity: Requires water for nutrients and minerals to be absorbed by plants

Non-distribution: Less mobile elements (e.g., phosphorus) stay in the individual granules until accessed by plant roots.

Rejection: Roots turn away from hot granules with too-high levels of potassium or nitrogen.

Inconsistency: Nutrition or mineral content of each granule varies and cannot be assured.
Pros and Cons of Granular Fertilizer

FACTOID: For centuries, food crops in China and Japan grew on soil fertilized with human feces, the smell of which spread around agricultural provinces.

What is Liquid Fertilizer?

Liquid fertilizers can be natural concentrates or extracts, or they can be commercial products sold in agricultural stores as natural extracts, liquid concentrates, emulsions, or gels.

One advantage is that you can precisely control liquid fertilizers to provide a steady supply of nutrients. For instance, you can stop feeding dormant plants in winter or increase feeding for new growth.

What is a Liquid Fertilizer?
What is a Liquid Fertilizer?

The main disadvantages for small-scale home gardeners? You need to a) remember to do it every time, b) never go away on long trips, and c) you can’t use them for the slow release of nutrients.

What are the Subtypes of Liquid Fertilizers?

Subtypes of liquid fertilizers include 1) liquid concentrates, 2) natural extracts and concentrates, 3) liquid emulsions, and 4) gels. The best liquid fertilizer for plants will depend on the plant it will be applied to.

Liquid FertilizersConcentrated Liquid FertilizersLiquid Emulsion Fertilizers
UrineAnhydrous liquid ammoniaFish emulsion fertilizer
Compost extractAmmoniatesHydrolyzed fish liquid
Grass extractAqueous ammoniaWater-in-oil emulsion fertilizer
Seaweed extractAmmonium nitrate and ureaPinolene polymer emulsion
Mulch extractNitrogenous fertilizersSoluble calcium emulsion
Chicken manure extractPotassium, phosphorus, nitrogen calcium blendsAmmonium nitrate emulsion, suspension, or gel
Aquarium waterUreaEmulsifiable concentrates
The Different Subtypes of Liquid Fertilizes

FACTOID: Colloidal clay and bentonite additives are used to prevent crystallization in liquid fertilizers during long storage.

What are Concentrated Liquid Fertilizers?

Concentrated liquid fertilizers dissolve and mix with water more rapidly than powders or other dry forms and therefore work more effectively. These are best for hydroponic plants.

What are Natural Extract Fertilizers?

Extracts or natural concentrates are a subtype of liquid fertilizers that are more concentrated through processes such as pressing and straining. Ideally, the excess water content must be removed, often by evaporation.

What are Emulsion Fertilizers?

Liquid emulsion fertilizers often come with complimentary A and B solutions. When the two solutions are combined, the nutrients and elements react with each other.

What are Gel Fertilizers?

Gel fertilizers such as liquid gel, starch gel, and seaweed gel combine the advantages of powder and liquid fertilizers. Slow-release gel fertilizers provide a high ratio of nitrogen, phosphorus, potassium, and other nutrients per liter of the product (yes, they’re completely water-soluble).

Advantages and Disadvantages of Liquid Fertilizers

Here’s a quick summary of the most common pros and cons of liquid fertilizers such as extracts, concentrates, emulsions, and gels.

Subtype of Liquid Fertilizer

Advantages of Liquid Fertilizers

Disadvantages of Liquid Fertilizers

Liquid Extract FertilizerEconomical: Natural liquid fertilizer extracts can be diluted with water for more use per drop
Safe: Natural extracts cannot burn or shock plants. There are no harmful chemicals or toxins.
Ease of use: Natural fertilizer extracts can be easily applied by using either foliar or fertigation methods.
Time & effort: Creating natural liquid fertilizer extracts requires much time and effort for mixing, fermentation, pressing, and containing.
Storage & preservation: Since they do not contain preservatives, natural liquid fertilizer extracts cannot be stored for a long time. They are best used when fresh.
Content precision: There is no way to precisely measure or identify the nutrient or chemical content of natural liquid fertilizer extracts.
Concentrated Fertilizer Strength control: Concentrates can be diluted with water for starter plants
Consistency: Each drop contains the same amount of nutrition and minerals.
Adaptability: Will blend with other products (e.g., for crop protection)
Absorption: Nutrients are quickly absorbed by plants
Evaporation: Nutrients and minerals may evaporate along with the liquid.
Drainage: Nutrients can be washed away by flowing water and can contaminate underground water sources.
Storage: Will settle or salt out when stored for long periods. Water content means costlier shipping due to bulk and weight. Leakage is a concern.
Emulsion FertilizerRequires mixing: Emulsions are composed of two liquids that must be mixed to activate the fertilizing agent.
Cost: Due to special production and packaging requirements, emulsion fertilizers can cost more than commercial fertilizers in liquid or dry forms.
Requires mixing: Emulsions are composed of two liquids that must be mixed together to activate the fertilizing agent.
Cost: Due to special production and packaging requirements, emulsion fertilizers can cost more than commercial fertilizers in liquid or dry forms.
Gel Fertilizer Handling: Gels are handled more easily than liquids; spills are recovered easier and faster.
Slow-release: Gel fertilizers are particularly useful when you need fertilizers that slowly release nutrients. This means you can’t over-fertilize your plants.
Conservation: Gel fertilizers do not allow volatile nutrients to be wasted through leaching or volatilization.
Unfamiliarity: Most soil fertilizer users are unfamiliar with gel fertilizer products and their proper applications.
Cost: Due to specific production, packaging and container handling, requirements, gel fertilizers may cost more than liquid or dry commercial fertilizers.
Leakage: Gel fertilizers can leak when containers are subjected to undue pressure.
Pros and Cons of Liquid Fertilizers

What NPK Ratios are Used for Indoor Herbs?

Here’s a table of NPK ratios for indoor herb gardening.

HerbsN (nitrogen)P (phosphorus)K (potassium)
Basil101010
Chives5105
Cilantro2486
Coriander301010
Lemongrass201010
Oregano302030
Parsley301020
Rosemary121217
Thyme16200
General fertilizers888
Recommended NPK (Nitrogen, Potassium, Phosphorus) for 10 Indoor Herbs

You’ll find many resources online regarding recommended NPK ratios for lawn or yard grass, rooting purposes, and specific plants such as tomatoes and other garden vegetables.

Which is better: foliar spray or soil fertigation?

You can use liquid fertilizers either way. Here’s a summary of what you need to know.

UsageProsCons
Foliar sprayApplication: Fertilizers are irrigated for ground absorption (via roots)

Supplementation: Can supplement foliar-applied nutrients
Limitation: Rain, wind, heat, or pests limit effectiveness.

Short availability: There is short-lived nutrient availability
Soil fertigation Application: Fertilizers is irrigated for ground absorption (via roots)

Supplementation: Can supplement foliar-applied nutrients
Escape: Nutrients can be carried away by water out of reach of plant roots.
Pros and Cons of Foliar vs Soil-Type Liquid Fertilizers

PRO TIP: Since nutrient intake is higher when absorbed via roots (compared to the foliar spray) always dilute organic liquid fertilizer before fertigation.

FAQs

How long does it take for fertilizer to work?

If quick-release fertilizer is used, plants absorb nutrients in 15 to 24 hours. If you use slow-release fertilizers, you’ll see the effects any time after three to 10 weeks.

How long do organic fertilizers last in the soil?

Organic fertilizers need about 2–6 weeks to decompose but can nourish plants from three months up to 10 years. Nutrients in liquid fertilizers are immediately consumed by plants—the fertilizer remains in the soil for two weeks at most. On the other hand, dry or granular fertilizer remains active in the soil for about 6–8 weeks.

Can I mix granular fertilizer with water?

Granular fertilizer can be mixed with water. Home gardeners should completely dissolve dry fertilizer in hot water before use. The water temperature should be around about 180°F or 82°C.

Can I turn granular fertilizer into liquid?

Granular fertilizers can and should be turned and diluted into a liquid solution for proper application. Soak 1 cup of granular organic fertilizer in one gallon of water for 24 hours, with occasional stirring. Strain out the solids. Use the liquid as fertilizer.

Why does granular fertilizer have more salt content?

As a slow-release fertilizer, granular fertilizer is highly concentrated with nutrients that last longer. Higher salt content is due to high concentration. If this doesn’t work for one’s plants, switch to organic, natural, or diluted liquid fertilizer.

How do I know when I must fertilize?

Plants must be fertilized once the following signs are seen: 1) purple, reddish, or dying plant parts, 2) stunted growth, 3) dark veins on yellow leaves, 4) dull green leaves, 5) reduced flowerings, and 6) rotting blossom ends.

Summary of Liquid vs Granular Fertilizer

Fertilizers can be gaseous (not available commercially), liquid (including concentrates, emulsions, and gels), as well as solid (including powders, pellets, sticks, and cakes). Solid fertilizers can be slow-release or fast-acting.

Go for pelleted fertilizer if you buy it in bulk for more savings and easier storage and handling. Pellet fertilizer releases nutrients gradually over the growing season. Use liquid fertilizer for quick absorption of nutrients to correct the severe nutritional deficiency.

Organic fertilizers improve the soil and provide a slower distribution of NPK nutrients and micronutrients. Synthetic or chemical fertilizers feed plants quickly with specific ratios of NPK nutrients. Unfortunately, the need for constant replenishment is bad for the soil and the environment.

Sources

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