Liquid vs Granular Fertilizer [Pros and Cons] With Science

Wouldn’t it be great if you can just quickly choose the best liquid or granular 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 best results.

What are the Types of Fertilizers?

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:

Liquid fertilizerThese act faster than solids, and can be spread faster over larger areas such as farms and orchards.
Dry fertilizerDry fertilizers such as powders, granules, pellets, and cakes are best for small gardens and farms because of lower cost, better control of nutrient release, easier storage, and control of wastage.
Gel fertilizerGel fertilizers combine the advantages of both dry and liquid fertilizers designed for slow or controlled nutrient feeding. They contain specific NPK macronutrients and chelated trace elements. They’re water-soluble and provide a high ratio of nutrients per liter.

What Fertilizer Should You Use?

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.

Liquid Vs Granular Fertilizer – Infographic

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

Nitrogen (N)The first NPK numberFunction: Nitrogen helps develop the parts of plants that you see above-ground, 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 numberFunction: Phosphorus makes plants resistant to pests and diseases as well as helps in root growth and development.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 numberFunction: Potassium helps plants to develop buds, flowers to blossom and fruits to grow.Deficiency: Potassium deficiency in plants show as chlorosis, or yellowing between the veins of leaves, scorching at the edges of leaves, and some plants show purple spots under the leaves.
Example 3NPK 12.10.20 fertilizer for tomato plants: One kilo includes 120 grams N, 10 grams 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.
Trace elements (not coded)Minuscule quantities of calcium (Ca), sulphur (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.

PRO TIP: Other countries use NPKS where S stands for sulphur.

Know Your Fertilizer: What NPK really means

What Is Granular Fertilizer?

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

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

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 fertilizer 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 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 as well as DIY fertilizers in concentrated pellets or chips are made for ease of application and for the slow release of nutrients. Examples are chicken manure, fecal sludge, wool pellets, goat pellets, and fish pellets.
PowdersCommercial 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.
SludgeMunicipal sludge from community sewage can be collected, dried, treated, and ground into biosolid compost for ease of application as 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.

PRO TIP: Hammer the spikes into soft, damp topsoil along the dripline for nutrient distribution and root contact when watered.

What is Better? Liquid vs Dry Fertilizer

What are the Pros and Cons?

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

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.

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

How to install fertilizer spikes & how they work.

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.

The disadvantages? 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 slow release of nutrients.

  • Liquid concentrates: 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.
  • Extracts or natural concentrates: Liquid fertilizer extracts are more concentrated by pressing, straining, and when most of the water content is removed, often by evaporation.
  • Emulsions: Liquid fertilizers that come with A and B solutions are called emulsions. When the two solutions are combined, the nutrients and elements react with each other.
  • Gels: Gel fertilizers such as liquid gel, starch gel, and seaweed gel combine the advantages of powder and liquid fertilizers. Slow-release fertilizers provide a high ratio of nitrogen, phosphorus, potassium, and other nutrients per liter of product (yes, they’re completely water-soluble).
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

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

Liquid Fertilizer: Pros and Cons

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

Liquid Extract Fertilizer: Pros

Liquid Extract Fertilizer: Cons

  • Economical: 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 require 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.

Liquid Concentrate Fertilizer: Pros

Liquid Concentrate Fertilizer: Cons

  • 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 Fertilizer: Pros

Emulsion Fertilizer: Cons

  • Organic: Emulsion fertilizers made from organic elements do not harm the environment and are mild to plants.
  • Nitrogen: Fish or kelp emulsion fertilizers have high nitrogen content that works quickly and can be made at home.
  • 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: Pros

Gel Fertilizer: Cons

  • 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

PRO TIP: Emulsions are liquid fertilizers with A and B solutions. To fertilize, the two solutions must be combined

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 two to six 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 soil from about six up to eight weeks.

Can I mix granular fertilizer with water? Yes. You should completely dissolve dry fertilizer in hot water (about 180° F).

Can I turn granular fertilizer into liquid? Yes. 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 your plants, switch to organic, natural, or diluted liquid fertilizer.

How do I know when I must fertilize? You have nutrient deficiency when you see generalized (not localized) symptoms of purple, reddish, or dying plant tissue (necrosis), stunted growth as well as:

  • Dark green veins on pale green or yellow leaves (chlorosis) needs nitrogen;
  • Dull, dark green or purplish leaves (interveinal chlorosis) towards the base means potassium is low;
  • Reduced flowering means phosphorus is low;
  • Rotting ends of blossoms means calcium is needed.

Note: Before applying fertilizer, check if it’s too much water that’s turning leaves yellow or pale green or if it’s the lack of water that results in dying or dead leaves

What NPK ratios are used for indoor herbs? Here’s a table of NPK ratios for indoor herb gardening.

Table 7: Recommended NPK for 10 Indoor Herbs

HerbsN (nitrogen)P (phosphorus)K (potassium)
General fertilizers888
Recommended NPK (nitrogen, potassium, phosphours) for 10 Herbs

You’ll find many resources online regarding recommended NPK ratios for lawn or yard grass, rooting purposes, and for 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.

Foliar sprayApplication: Can be sprayed on leaves

Supplementation: Can supplement soil-applied nutrients

Timing: Can correct mid-season deficiencies
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.

FREE PDF: Fertilizer Types and Calculating Application Rates (3 pages)

But, before you go, here are your key takeaways.

Quick Takeaways

Because plants can’t tell us when they’re hungry or what they need to eat, it’s our job to know that and provide the right input.

Now you know: their lives are in our hands.

When choosing the better fertilizer, know what’s available and how to use it, what your plants need, and what the environmental effects will be. For example:

  1. Pellet VS liquid: Go for pelleted fertilizer if you buy 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.
  2. Fertilizer forms: 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.
  3. Fertilizer content: 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.

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