Compost as a Fertilizer – Usage and Application Guide

Organic waste from the garden and kitchen can be used as a fertilizer for your plants as well as a soil conditioner. You’ll find out everything you need to know about compost fertilization here.

Latin term compositus, which means “composed,” is the source of the word “compost.” A wide range of organic waste can be used to create compost. The qualities of the finished product can differ as widely as the raw elements.

Using helpful microorganism conversion products, you may fertilize your plants and enhance the soil.

In this post you can learn about

Compost matter Composition and Properties

Compost is the humus that results from the decomposition of organic matter. Compost’s qualities are dependent on the raw materials used, as previously stated.


This compost is created from organic waste and herbaceous green waste. Because so much nutrient-rich material was used, the nutrient level is extremely high. As a result, it can be used as a fertiliser for plants.

Green compost

This compost is made solely from green garbage and other difficult-to-decompose materials. Because it contains fewer nutrients, it encourages the creation of humus rather than fertilizing plants.

However, organic or green waste compost is merely two pillars of a vast array of options. Combinations of these two extremes are also feasible, with features that fall midway between them. As the last point, factors like composting length and circumstances affect the end output.

Fresh compost

Compost that is four to eight weeks old yet still decaying. Even after all these years, the original materials’ structures may still be recognized.

Ready compost

For at least six months, a compost pile withered away. Almost little but friable, fragrant debris is left here.

Mature compost

After two to three years of decomposition, you’ll have finished compost. Even the most durable wood material has been reduced to humus by this point.

Compost Carbon-to-Nitrogen Ratio

Based on the beginning components and decomposing duration, compost has a C/N ratio of 15:1 to 25:1. The carbon-to-nitrogen (C/N) ratio tells us how much carbon (C) and nitrogen (N) a substance has. When the C/N ratio falls below 20:1, bacteria begin to break down the material, releasing nutrients instead of creating humus.

Degradation is slowed and humus formation is more likely when the C/N ratio is greater than 25:1. The fertilizing or soil-improving effects of compost may or may not predominate, depending on the type of compost used. A smaller C/N ratio is common in newly created composts and those made from nutrient-rich material; a higher C/N ratio is common in mature composts and those made from less nutrient-rich material.

Compost as Fertilizer for Garden Plants

Compost of any kind can be used to improve soil and fertilize plants. Even so, the degree to which an effect is felt is primarily determined on the type of compost utilized. Nitrogen, potassium, and phosphorus are most likely to be balanced if they are all present in equal amounts.

Phosphorus and potassium concentration are more frequently than not much higher than nitrogen content. Plants have substantially higher nitrogen requirements, thus this nutrient ratio is unsatisfactory for them. As a result, we suggest using compost in conjunction with another fertilizer.

It’s important to observe the compost’s high concentration of trace nutrients, which your plants require in equal measure as the more important macronutrients they receive. The suitability of several types of compost as fertilizer is shown in the table below. Soil fertilizing agents enrich the soil, whereas plant fertilizers supply nutrients to plants.

Nutritional humus is a type of unstable and easily degradable humus that has a high nutrient content and is therefore considered undesirable. If used properly, it can give plants nutrition while leaving the soil untouched.

Effects of Compost on Soil and Plants

Like organic fertilizers, it has a comparable impact as plant food. Plant nutrients are weather-dependent, therefore they aren’t readily available all at once. Overfertilization can cause plant harm, and preventing it helps keep the soil’s humus from being depleted. Furthermore, the gradual and microbiological conversion has a long-term effect.

When compost is employed, the soil fertilization impact usually takes center stage. The swellable, light humus flakes boost light soils’ ability to retain water. Moisture is effectively retained in the soil as a result of this. Compost loosens thick soils, allowing roots to breathe and water to drain more effectively. As a result, there is less risk of waterlogging, which is bad for plant growth in general.

You may be perplexed as to why compost has such disparate results on different types of soil. The seeming inconsistency can be reconciled, however, by the pore size. Sand has a huge number of open holes, and water cannot be stored there. Think of it like a coating of coarse gravel to get the idea: The water simply passes through it, and the layer quickly dehydrates. When it comes to pore size, clay soils behave in the exact opposite way. A large number of small dirt holes can be found on them.

Because the water cannot drain downward, when it rains heavily, the soil might become completely saturated. As a result, plants experience oxygen deficiency at the root. In addition, the water in the minuscule spaces is completely inaccessible to them since it is trapped in the soil pores in an excessively tight manner. Humus is now a go-between. It has medium-sized pores rather than huge or small ones. These have a higher water holding capacity than sand and a higher water drainage capacity than clay. These medium-sized interstices are ideal for root absorption.

Many nutrients can be stored on the surface of humus molecules alone, making them later available. The so-called clay-humus complexes are also created when clay minerals are combined with humus, and they offer exceptional capabilities in the field of nutrient and water storage.

Only with them can larger “crumbs,” which can be seen with the naked eye, be formed. As a result of the enormous number of loosely linked molecules, clay-humus complexes have a relatively wide surface area. This explains how they can store so much water and nutrients. They’re elastic, so walking on them causes less compaction, which means your soil will be kinder to you because it’ll cushion your fall.

Stable permanent humus is made up of humic acids that range in hue from dark brown to black. Due to the fact that dark soils absorb more sunlight, they warm up more quickly in the spring. In addition, effective soil aeration aids warming since the air in the soil warms up more quickly than water. Humus, on the other hand, aids in soil aeration.

Last but not least, honor should be given to the unsung heroes of your garden compost – Microorganisms. Because they play a role in so many soil processes. Spreading compost is a joy for them because organic material is the foundation of their existence. It gives them the energy and resources they need to break down and convert raw materials, deliver nutrients, and carry out a variety of other tasks that benefit your plants.

Tip: There are some instances where compost might have a negative impact on your soil or plants. Nitrogen leaching can occur if there is a lot of rain in the fall while the soil is still warm and alive. In addition, if the temperatures in the compost bin is not sufficient enough during decomposition, fungal infections and undesired seeds of wild weeds can be transported away from the area. For more detailsĀ on hot and cold rotting, see the section below titled “Creating Compost.”

Use compost as a fertilizer

The table below shows how much compost is required and how it should be used. It is important to remember that compost should not be applied in a deep manner while using it. Because it contains a large number of air-breathing microorganisms that must survive in order to complete the composting process, it is critical that oxygen be available while simultaneously shielding the compost from the immediate weather.

Compost should be worked in as deeply as possible, but just superficially. A specific case of mulching is when a thick layer is put on top of the soil without being integrated.

When to apply Compost to your Garden

Compost should be applied in the dead of winter or early spring for best results. Seasons such as late summer and early fall that are likely to be rainy should be avoided. Composts that are very rich in nutrients continue to release nutrients even when the soil temperature is high, and these nutrients can be carried away during heavy rains.

When nitrogen seeps into natural waters from the earth, it pollutes both the water and the environment. Mature composts and green waste composts, which contain fewer nutrients, release fewer nutrients, and are safer to use. If at all feasible, use them when it’s cloudy and not too dry outside.

Using Compost in Garden Beds

Compost can be distributed in a 0.2 to 7 cm layer, depending on your goals. A small layer of annual maintenance is all that’s needed to keep the humus level where it should be while also providing a nutritional foundation. Increasing the humus content of the soil with completed or mature compost already necessitates the use of relatively higher quantities.

Nevertheless, the compost is only worked in very shallowly in both circumstances. Compost from green waste is used to create a thick layer of mulch, but it is not pushed into the ground. Mulching should be done every three to five years.. if not more. The section that follows has more information about compost’s additional applications.

Where to get Compost Soil

If you’re interested in learning how to make your own compost and get the many benefits it has to offer, check out our guide on how to build a compost bin. This page includes a quick tutorial to effective composting. Compost bin construction has several advantages, but it takes some forethought and consideration.

Layering trash or moving it occasionally for aeration, for example, may be required to ensure adequate decaying. This procedure may also involve a variety of aggregates that are more or less necessary. With the help of our unique article, you may also make your own compost.

Or maybe you don’t have the time to compost yourself and need high-quality compost right away so that you can plant something new or make an entirely new bed? Compost, or humus as it’s often known, is readily available in a variety of forms.

A local recycling facility, where organic compost and green compost can be purchased separately or as a blend, is clearly the most affordable alternative. However, those living in less rural locations have access to more cheap housing options.

A variety of compost forms are included in potting soil, which is sold in various-sized bags. Because the raw materials used to make the soils can vary widely, the variety of soils available is also wide. You’ll discover everything that you need to know regarding buying humus in this subsequent essay.