Can You Combine Organic and Inorganic Fertilizer?

a man spreading fertililzer granules on soil

If you’re unsure which fertilizer is best, the solution isn’t to choose one over the other. Instead, you can combine organic and inorganic fertilizers to give your lawn an optimal balance of essential nutrients.

Organic fertilizers can enrich your lawn soil with organic matter and beneficial microbes over time, while inorganic fertilizers can quickly supply it with precise nutrients. With a perfect blend of these fertilizers, you can make your lawn healthy, vibrant, and resilient.

What to expect when you combine organic and inorganic fertilizer

Before delving into what happens when you combine organic and inorganic fertilizers, here’s a quick overview of each type:

Organic fertilizers, such as manure and compost, typically contain a mix of macronutrients (nitrogen, phosphorus, and potassium) and micronutrients (e.g., copper, iron, and zinc). While their nutrient content can vary, these slow-release fertilizers contribute to the long-term health of lawns.

Inorganic fertilizers, on the other hand, are known for their specific nutrient compositions. These quick-release fertilizers can deliver the exact N-P-K ratio tailored to your garden and lawn needs.

Type of fertilizerProsCons
Organic fertilizer– Improves soil structure
– Increases microbial activity
– Promotes long-term soil health
– Reduces risk of nutrient leaching
– Enhances nutrient and water retention
– Slow release of nutrients
– Variable nutrient content
– Bulkier to transport
– More expensive
Inorganic fertilizer– Fast release of nutrients
– Precise nutrient formulations
– Lower cost per unit of nutrient
– Easy to over-apply
– Can lead to nutrient leaching
– May degrade soil quality over time
– Can cause environmental pollution

Effects of mixing organic and inorganic fertilizer

person rertilizing lawn
Adobe Stock

Mixing these two types of fertilizers is not necessarily a new concept. If you’re using organic mulch for your landscape, it provides your soil with organic matter and other essential nutrients. Then, when you apply synthetic fertilizer to give your lawn a nitrogen boost, you unknowingly combine organic and inorganic fertilizers.

This combination of practices — using mulch for its organic benefits and supplementing with inorganic fertilizers for targeted nutrient needs — is a good example of a practical approach to integrated fertilization.

According to Andrew McGuire, agronomist at Washington State University Extension, a specific “combination of organic amendments and synthetic nitrogen fertilizer is good for soils, good for water quality, and good for farmers.”

So, it still boils down to adding the right amount of nutrients at the right time. Mixing organic and inorganic fertilizers will be a win-win situation, providing both immediate and long-term benefits to your lawn.

Benefits of combining organic and inorganic fertilizers

illustration depicting organic fertilizer and synthetic fertilizer
Infographic by Juan Rodriguez

Here are some reasons why it can be a smart lawn care strategy to combine organic and inorganic fertilizer use:

  • Balanced nutrient supply: A mixed usage of both types of fertilizers can ensure a more complete and balanced nutrient profile. Synthetic fertilizers provide immediate nutrient boosts during critical growth stages, while organic fertilizers improve soil fertility.
  • Improved soil health: Organic fertilizers can improve soil structure by adding organic matter and increasing microbial activity. But if you add recommended amounts of inorganic fertilizers, it can complement this by supplying specific nutrients that grasses can quickly absorb — leading to better water infiltration and enhanced soil resilience.
  • Cost-effective solution: Since inorganic fertilizers are more budget-friendly and readily available than organic fertilizers, combining them can reduce the overall cost.
  • Reduced environmental impact: Incorporating organic fertilizers can help lessen the risk of groundwater contamination and nutrient runoff typically associated with excessive inorganic fertilizer use. With this proactive approach, you can do your part in saving the environment.
  • Customizable option: Using the right combination of organic and inorganic fertilizers allows you to optimize the nutrient uptake of your turf, promoting healthy growth with over-application.

Potential challenges and solutions of combining fertilizers

feeding lawn with granular fertilizer for perfect green grass

Problems usually arise from incorrect application or overuse of one type of fertilizer over the other. While inorganic fertilizers offer a quick nutrient boost, they can be quickly depleted, often prompting the temptation to add more. But if you give in and over-apply inorganic fertilizers, it can result in fertilizer burn, damaging your plants.

Organic fertilizers are non-toxic and environmentally friendly. However, every homeowner knows they’re not as affordable unless prepared at home from waste materials. These fertilizers have a slow-release effect that allows them to provide nutrients consistently. But if you rely on them solely, it can be consistently expensive.

If you combine organic and inorganic fertilizer use, you can have lush and healthy grass. However, you must do it responsibly and carefully to avoid potential issues such as:

Nutrient imbalance

Problem: When you combine organic and inorganic fertilizers, there’s a high probability of over-fertilization. If there’s an imbalance of nutrients, it can lead to nutrient toxicity and possible environmental harm.

Solution: To avoid this problem, conduct a soil test prior to lawn fertilization and follow the recommended application rates. After fertilizing your lawn, monitor the soil conditions and health of your grass regularly. This way, you can easily make any necessary adjustments.

Environmental concerns

Problem: Using inorganic fertilizer can contribute to nutrient runoff and environmental pollution, especially if not managed properly.

Solution: Combining them with organic fertilizers can help reduce this risk. The organic matter supplied by controlled-release fertilizers improves soil structure and water retention, lessening the odds of nutrient leaching.

Cost and availability

Fertilizer in soil. The concept of plant care is the need for feeding with various fertilizers. Text N, P, K, Ca, Mg, S, Mn, Cl, B, Fe, Zn
Adobe Stock

Problem: Although their long-term benefits often justify the investment, organic fertilizers can be more expensive and less concentrated than synthetic fertilizers.

Solution: To manage costs, you can make your compost using food waste or other locally sourced organic materials. For inorganic fertilizers, buying in bulk and selecting formulas that address your specific soil and lawn needs can be cost-effective.

How to combine organic and inorganic fertilizers effectively

Determining the nutrients your lawn needs is always the first step when applying fertilizer, regardless of your chosen method. You can test your soil by sending samples to a lab or by using a DIY kit. Experts recommend having your soil tested every two to three years, but you can do it more often if you want to closely monitor its fertility.

Based on the recommendations in your soil test results, you can create a fertilization plan using any of the following application techniques:

  • Layering: For this method, you can apply organic fertilizers first, followed by inorganic fertilizers. This approach can help provide an immediate nutrient boost from inorganic compounds while enriching your soil with organic matter.
  • Mixing: Combine both types of fertilizers in a single application. For example, you can mix compost with a balanced synthetic fertilizer before applying it to your lawn or garden.
  • Sequential application: Apply organic fertilizers at the onset of the growing season to build soil health. Then, spread inorganic fertilizers during key growth stages for an immediate nutrient boost.

Sample combinations of organic and synthetic fertilizers

Dung or manure on the farm when the morning sun is shining
Adobe Stock

The key is to choose a balanced organic fertilizer and supplement it with a compatible inorganic fertilizer. Here are some examples of effective fertilizer combinations:

  1. Compost + chemical fertilizer blend: During the growing season, add topdressing by mixing well-aged compost with a balanced chemical fertilizer with the right N-P-K ratio. The synthetic fertilizer offers an immediate nutrient boost, while the compost provides the long-term benefit of organic matter and slow-release nutrients.
  2. Manure + controlled-release fertilizer: This combination is best if your lawn is constantly depleted of nitrogen. The manure can provide a slow release of nitrogen, organic matter, and micronutrients, while the controlled-release fertilizers ensure a steady supply of nitrogen over time.
  3. Fish emulsion + water-soluble fertilizer: The fish emulsion is high in nitrogen and micronutrients, while the water-soluble fertilizer can deliver a balanced NPK ratio. When you dilute the mixture in water and use a foliar spray, you can provide a quick nutrient boost to your plants.
  4. Mulch + coated inorganic fertilizer: This combination can reduce nutrient leaching and minimize the need for frequent fertilization. The mulch helps conserve moisture, suppress weeds, and improve soil health, while the coated fertilizer gradually releases nutrients into the soil over time.

FAQ about combining organic and inorganic fertilizers

When is the best time to apply lawn fertilizers?

In general, the best time to fertilize your lawn is when your grasses are actively growing. Proper timing is crucial for lawn fertilization. If you do it randomly, you’ll just waste your effort, damage your lawn, or harm the environment.

To determine the right timing, first identify whether you have warm-season or cool-season grass. Then, refer to the table below for the best times to apply fertilizer to your lawn.

Fertilizer applicationWarm-season grassesCool-season grasses
First batchLate spring to early summerEarly to late spring
Second batchLate summer to early fallLate summer to early fall
WinterizerLate fall

Note: Regardless of your type of grass, remember to apply late summer lawn fertilizer to help your turf endure the cold winter months.

How can I be responsible when using fertilizers?

To use fertilizers responsibly and minimize negative impacts, consider the following practices:

  • Follow instructions: Always read and adhere to the manufacturer’s instructions and safety precautions on the fertilizer label.
  • Prevent water contamination: Avoid applying fertilizer to areas with natural drainage to prevent water contamination.
  • Protect children and pets: Keep the fertilized area off-limits to children and pets for at least 24 hours after application.
  • Clean responsibly: To prevent chemical runoff, clean applicator tools over grassy areas instead of washing them into the street.
  • Proper disposal: Dispose of fertilizer bags properly and follow local regulations for disposing of expired fertilizers.

Note that improper fertilizer application can adversely affect your turf, attract pests, increase soil salt content, and cause fertilizer burn. And even if you use a pet-friendly fertilizer, letting your pets play on the lawn before the fertilizers have been fully absorbed or dried can pose significant health risks to them.

From a broader perspective, incorrect fertilizer use and over-fertilization contribute to greenhouse gas emissions and severely harm aquatic life. 

How will I know if my lawn is over-fertilized?

Some signs to look out for include grasses turning yellow or wilting. Sometimes, it would look like your turf is healthy because it’s growing rapidly, but this doesn’t necessarily mean it’s strong and resilient. On the contrary, it will be weak and susceptible to pests or diseases.

When you over-fertilize your lawn, expect stunted growth, leaf burn, a rapid increase in soil and nitrogen, and even grass death.

Use the perfect balance of organic and inorganic fertilizer

Don’t get stuck trying to choose between organic and inorganic fertilizers. Combining the two types allows you to go the easier and more beneficial route. With proper planning, you can enjoy the advantages of both fertilizers while saving money in the long run. Remember to use the right amount of nutrients, proper timing, and an optimal application method.

If you don’t want to go through all the trouble, let Lawn Love connect you with a lawn care pro in your area. These experts have the tools and the know-how to combine organic and inorganic fertilizers properly and effectively.

Main Image Credit: Adobe Stock

Melanie Joseph

After discovering her passion for writing through her beauty blog, Melanie left her engineering job in California, became a writer, and never once looked back. When she isn't writing, she loves dipping in the pool, tending to the garden, or doing simple home improvement projects.