With the desire to always improve agricultural yield, compost and fertilizer have become a favourite. Some prefer compost while others prefer fertilizer. Then, some think they are the same. The similarities they have are the reason for this, and it can become a problem. Hence, all plant growers need to understand that there is a difference between compost and fertilizer.
In basic terms, compost helps the soil, which benefits the plant. Whereas, fertilizers have no role in soil health. Their only purpose is to make nutrients available for plant uptake.
I will talk about this later in the post while aiming to also discuss the benefits of each and if they can have a use together.
Let’s dive in and try to understand both better.
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What is compost
Compost is a mixture made by the natural decomposition of organic matter. Microbes and protozoa help catalyse the breakdown of organic matter. It leaves behind a mixture rich in nutrients for plants to uptake. It also has a role to improve the soil structure and quality.
The importance of compost cannot be underestimated. Their use has been common across all plant growers, ranging from commercial farmers to local planter such as myself.
Benefits of compost
Compost is formed by decomposing organic matter to give a mixture rich in nutrients for plants to uptake.
The benefits of compost for the soil and plant alike include:
Prevent soil erosion
Compost prevents soil from running off when there is a water storm. It has binding properties that clump the soil together. You can think of it as a glue for the soil and this is vital to prevent nutrients from being washed away.
Compost reduces water flow through the soil. This helps to prevent soil erosion as well.
Another property that helps to prevent soil erosion is the permeability of the heavy soil. After a water storm, the soil absorbs the water. This reduces water flow, which then prevents soil erosion.
Reserves water
Compost increases the permeability and infiltration of water in the soil. So… when it rains, the water does not flow from the soil into the sewages or drainage. Instead, the soil keeps the water available for the plants to uptake when needed.
Not only that, but compost can also transfer water within the soil. This allows plants to uptake and maximise their growth.
Environmental benefits
Compost has environmental benefits as it prevents emissions of dangerous gases.
We can add kitchen scraps, dead leaves or moulded fruit and vegetables to a compost pile. They decompose and break down to give nutrient-rich compost. For example, composting onions can have various beneficial affects on your soil
But, if you throw away food waste, it would go to landfill sites. This produces the potent gas methane. This can cause damaging effects to our atmosphere.
What is a fertiliser?
Fertilizers release available nutrients for plants to uptake. Fertilizers comprise three main nutrients. These are nitrogen, phosphorous and potassium.
Nitrogen helps with leaf growth and gives plants a pleasant green colour. Phosphorus helps with photosynthesis and nutrient movement within the plant. Potassium strengthens the plant’s ability to resist diseases. It also improves the yield and quality of what you grow.
Gardeners.com explain how to choose a fertilizer, as well as explaining if it is best to choose organic or synthetic.
Benefits of fertilisers
I often refer to fertilisers as ‘nutrient boosters’. This is because they increase the availability of nutrients for plants to uptake.
The benefits of this are:
Increase in yield
Fertilizers have a use commercially and locally to improve productivity. For example, commercially, fertilizers are added to wheat. This helps crops to grow faster and maximises their yield.
Help combat growing populations and demand
Because of the steady rise in population worldwide, the demand for food is now more than ever.
Thus, a sufficient amount of crops is a yearly need to meet the demands. Commercially, these crops have a role in food, agriculture and clothing. Without the use of fertilisers, crops such as wheat and barley are unlikely to produce high yields. This can have severe consequences to farming, trade and the economy.
Help with nutrient-deficient plants
When plants turn yellow or become discoloured, it can be because of malnourishment. These plants need more nutrients. Fertilizers are a great way to add a concentrated amount of nutrients to the soil. These nutrients are available for your plant to uptake.
When to add compost
It is best to add compost as a top dressing when you first pot the plant. I do this for all my plants, as compost has benefits not to ignore.
For example, when I repot succulents, I prefer to use cactus compost as it has good drainage and provides nutrients.
Every couple of months, add a new layer of compost on top of the soil when nutrients deplete.
Good Tip!
If you notice discolouration or yellowing of your leaves, it is best to add fertilizer. NOT compost. This is because compost has a much slower release of nutrients that can take weeks or months.
When to use fertiliser
You would add a fertilizer either initially or when the plant needs it. For commercial purposes, fertilizers are added to increase growth and yield of production.
Initially when planting
If you are a beginner, you will not know how rich your garden in nutrients. Hence, it is best to add some fertilizer to your soil when you first pot your plant. I remember when I first grew my first plant; I did not add no compost or fertilizer. The plant did not grow well and eventually, it died.
On the contrary, you may hear that some people never use a fertilizer. Luckily for them, their soil is nutrient-rich, and the plant can grow.
If you want clarity on how to decide if your soil is nutrient-rich, you will never know.
It is only when you start to grow often, you will come to know if your soil is nutrient-rich or not. It is just a matter of trial and error.
When choosing a fertilizer, you may find it difficult to understand what the numbers on the front of a bag mean and how they influence plant growth. The video below will explain this:
Plant becomes nutrient deficient
Fertilizers are used the plant becomes depleted of nutrients. The leaves will start to shrink and become discoloured/yellow as seen in the image below. It is best to add fertilizer when this happens. This will allow plants to instantly uptake the nutrients now available in the soil.
Stimulate growth to improve yield
You can also use fertilizer to stimulate growth. For example, you may have a plant that is growing well. But you want to increase its growth. Or get a bolder colour from the plant. Or increase its growth rate. For this, the addition of fertilizer is suitable to meet those requirements.
Similarities of compost and fertilizer
Farmers have described compost as black magic. This is because it can provide a lot of nutrients for the plant. Similarly, fertilizers can play a crucial role in providing nutrients for plants too.
Compost and fertilizer provide nutrients, such as ammonia phosphorus and potassium in plenty.
On a commercial level, both have uses to increase crop yields and help plants to grow at a faster rate.
It is possible to make both compost and fertilizer at home. The procedure is simple and you can adjust based on what you choose to grow.
Differences between compost and fertilizer
We can use compost as a soil conditioner. It acts as a pH buffer, preventing the soil from becoming too acidic or alkaline. But, fertilizers don’t change the properties of the soil. Their purpose is to only enrich the plant with nutrients.
Fertilizers allow a quick release of nutrients for the plant. On the other hand, compost has a slower release of nutrients. For those who have a depleted plant, a quick fix to replenish those nutrients is by the addition of fertilizer. It will work to make nutrients readily available.
The composition of fertilizers for compost is different. Compost comprises organic matter that is decomposed. Fertilizers can be liquid, granular or powder and are chemical or organic. The three major elements in fertilizers are nitrogen, phosphorous and potassium.
Limitations of fertiliser
As fertilizers do not benefit the soil, this can lead to limitations with their use. This includes:
Easily washed away from the soil
Fertilizers can saturate into the soil quickly, and this makes them readily available. But this also can make them prone to being washed away from the soil when it rains.
Hence, when it rains, nutrients will deplete from the soil. The plants will have no nutrients to uptake. If you live in an area of constant rain, it is best to use fertilisers with compost.
The washed away fertilizers can have environmental implications. The fertilizers are high in nutrients and can cause random algal blooms.
Also, there are reports of chemical fertilizers in drinking water. This has caused health complications, especially in areas close to agricultural work.
Does not improve the soil.
Fertilizers are an ‘additive’. Their sole purpose is to feed nutrients to plants. However, they play no role in soil health. Hence, they have no role in improving soil drainage or retention, erosion or pH.
Can you compost and fertilizer together
To get the best growth, it is best to use both compost and fertilizer together. Compost also holds nutrients, such as ammonium phosphorus and potassium. Hence, the amount of fertilizer you need to use is less. It is best to use compost and fertilizer in a 2 to 1 ratio.
Add the mixture to the top of the soil as a top dressing. This helps to protect the soil bed while also making the nutrients readily available for plants to uptake.
Good Tip!
You can SAVE a lot of money by mixing compost with fertilizer. During rainfalls, fertilizer is washed away BUT if you mix with compost, compost has binding properties that prevent soil erosion. Therefore, you won’t have to buy fertilizer as often.
Final words
Both compost and fertilizer have a beneficial effect on plants. However, it is important to know the difference between compost and fertilizer.
So let’s run through this one last time… compost is the food for the soil whereas fertilizer is food for the plant.
Also, fertilizers are used ONLY to add nutrients for plants. Whereas compost has MANY uses for both the soil and plant.
It is important to understand that plants can grow without the use of fertilizers. This is because compost releases essential elements already found in fertilizer. But, if you use fertilizers only, the soil may lack the conditions for plant growth regardless if nutrients are taken up.
Keep these differences in mind, know when to use comport or fertilizer and if you are up for the challenge, why not try both together.
