Growing your own garden can be a rewarding hobby. Whether you are waiting to enjoy fresh garden vegetables or anxious to see your flowers bloom, you will spend plenty of time tending your garden. Some factors that affect your garden’s growth are obvious – like water and sunlight. However, when it comes to compost, mulch, fertilizer, and soil, many don’t know the difference between them or how to use them correctly.
So, what is the difference between compost, mulch, fertilizer, and soil? All four are essential components of the growth and cultivation of plants and crops. They can best be defined by their location and use.
- Compost is decomposed organic material that is placed underneath the soil – close to the plant’s roots – and helps to remove toxins from the soil.
- Mulch is an organic material that is placed on top of the soil to help prevent weeds from growing and can include things like wood chips, leaves, and straw.
- Fertilizer can be both natural and chemical and is used to enhance the growth of plants.
- Soil is the part of the earth from which plants grow; it is made up of broken rocks and minerals, decaying living organisms, living organisms, water, and air.
Compost, mulch, fertilizer, and soil are all beneficial to the growth of plants and the cultivation of crops in different ways. Which of these you choose to use for your plants, is completely up to you. There are many factors that can affect the way that you tend your plants, like the climate where you live and the composition of the soil in your yard.
What is Compost?
Compost is made of decomposed organic material. You can purchase compost or make it yourself. It is meant to be placed underneath your plants, resting at their roots. To use compost, you dig up your garden area and place a layer of compost at the bottom before refilling it with soil. You can also work compost into the soil by placing it in between plants and working it in with your hands.
Compost is a wonderful addition to any garden because it conditions the soil and allows the plants to grow stronger and healthier. Over time, it removes toxins from the soil, and the nutrients in the soil become more readily available to the plants. Compost finishes the natural soil cycle by returning organic material into the soil.
When looking for compost to use in your garden, look for a dark-colored compost with an earthy aroma that has a more even texture. You don’t want a lumpy compost because it may have organic material that isn’t fully decomposed that can take nutrients away from your plants.
What is Mulch?
Mulch is an organic material that is placed on top of soil in your garden, and it can be made of many things. Most commonly, you will see wood mulch – mulch that is made from wood pieces. Shredded leaves are another popular form of mulch. Organically dyed newspaper and straw can even be used as mulch.
Mulch has a few different purposes:
- It helps to retain the moisture and nutrients in the soil.
- It helps to prevent the growth of weeds.
- It helps to regulate the temperature of your plants to allow them to thrive.
- It prevents soil erosion.
- It improves soil structure as it decomposes. (only organic mulch)
Mulch can be both organic and inorganic. Some people prefer inorganic mulch, like stones or gravel, because it has no chance of competing with their plants for nutrients and it doesn’t decay. However, organic mulch offers the added benefit of improving soil structure. So, using organic or inorganic mulch is entirely up to you.
What is Fertilizer?
Fertilizer is a plant additive that can be either naturally or chemically made. It adds essential nutrients to the plants to help them grow properly. There are many different nutrients that fertilizers supply for plants.
| Significance | Nutrients |
| 3 Main Macronutrients | nitrogen, phosphorus, potassium |
| 3 Secondary Macronutrients | calcium, magnesium, sulfur |
| Micronutrients | Copper, iron, manganese, molybdenum, zinc, boron |
| Occasional | Silicon, cobalt, vanadium |
These nutrients are necessary for proper plant growth. For instance, nitrogen encourages leaf growth, phosphorus aids in root development, and potassium helps to ensure strong stem growth. Each nutrient has its own job to do within the plant growth process.
Different combinations of fertilizer are used on plants. You can use a single nutrient fertilizer that is a nitrogen-based solution, usually ammonium nitrate, urea, or calcium ammonium nitrate. There are also single nutrient fertilizers that are phosphate based called superphosphates. There is one widely used potassium-based single nutrient fertilizer called Muriate of Potash.
Multinutrient fertilizers are also regularly used. There are three binary fertilizers – NP, NK, and PK. NP fertilizer provides nitrogen and phosphorus. NK fertilizer provides nitrogen and potassium. PK fertilizer provides phosphorus and potassium. NPK fertilizers offer all three main macronutrients – nitrogen, phosphorus, and potassium.
Organic fertilizers are obtained or derived from living or formerly living things. They use things like animal waste, plant waste, compost, biosolids, bloodmeal, bone meal, feather mill, hides, hoofs, and horns. Some store-bought organic fertilizers use organic additives in their products like rock powders, ground seashells, seed meal, kelp, and cultivated microorganisms.
What is Soil?
Soil is a combination of organic matter, organisms (both dead and alive), minerals, gases, and liquids that help maintain life. Soil, alone, makes up the pedosphere – Earth’s body of soil – and it has four important purposes.
Soil functions as the following things:
- A means of plant growth
- A way for water storage, supply, and purification
- A modifier of the atmosphere
- A home for organisms
Every single one of these functions modify the structure of the soil. Soil exists all around the earth, but it is as different as it is widespread. Factors like climate, elevation, organisms within the soil, and the soil’s original minerals affect soil. In fact, soil is so complex and internally connected that soil ecologists consider soil as its own ecosystem.
In 2010, Estelle Dominati stated in Ecological Economics that
“soil acts as an engineering medium, a habitat for soil organisms, a recycling system for nutrients and organic wastes, a regulator of water quality, a modifier of atmospheric composition, and a medium for plant growth, making it a critically important provider of ecosystem services.”
Soil is an absolutely incredible resource.
There are various types of soil with different physical properties, making some of them very suitable for plant growth and others less suitable. Physical soil properties include texture, structure, bulk density, porosity, consistency, temperature, color, and resistivity. Soil mineral particles, commonly called soil separates, are sand, silt, and clay. Other parts of soil, called soil aggregates, iron oxides, carbonates, silica, and humus.
The best kind of soil for most plants is called loam soil. This soil is a mixture of sand, silt, and clay that is usually mixed with compost and peat moss. Loam soils hold water very well, are properly aerated, and have the right mix of minerals to promote plant growth.
The following percentages show the components of loam soil by percent volume:
- Water – 25%
- Gases – 25%
- Sand – 18%
- Silt – 18%
- Clay – 9%
- Organic matter – 5%
An In-Depth Look at Compost
Compost is “an aerobic method of decomposing organic solid wastes.” It allows farmers and gardeners to recycle organic waste materials and reuse it to fertilize future plants and crops. There are some conditions that must be met for compost to be successfully made.
To make compost successfully, you must consider the following three factors:
- Human management
- Aerobic conditions (meaning air is present)
- Presence of internal biological heat
For composting to be done properly, it must have four ingredients:
- Carbon – This is for energy. Materials high in carbon tend to be brown and dry, and they produce the heat for the compost.
- Nitrogen – This is to grow and create more organisms for the oxidation of the carbon. Materials high in nitrogen tend to be green and wet.
- Oxygen – This is for the oxidation of the carbon to promote decomposition.
- Water – This is needed in measured amounts to make sure that anaerobic conditions do not form.
Not only do these factors and ingredients need to be present, but there must be a specific ratio of carbon to nitrogen present in the compost. The ratio of carbon to nitrogen should be 25:1.
Additionally, there are different kinds of composting. First, there are slow and rapid methods of composting. Slow composting takes more time and relies solely on the components within the compost to prepare it. Rapid composting includes more human interaction and control with the composting during which the farmer or gardeners adds ingredients to make the composting process finish more quickly.
Specialized forms of composting include:
- Vermicomposting – different species of worms and their castings, humus, and manure are used to help the composting along
- Onsite composting – used by farmers, gardeners, or small organizations that just need to compost small amounts of organic waste; only suitable for small quantities of compost
- Windrow composting – good for large volumes of compost; commonly used for entire communities and collected by local governments; residents can use the compost for little or no cost
- Aerated static pile composting – not suitable for animal byproducts or grease from food; composts quickly and uses a more homogenous mix of organic waste like yard trimmings, food scraps, and paper products
- In-vessel composting – can work with almost all types of organic waste and requires the compost to be placed within a vessel for environmental conditions to be controlled during the compost; produces large quantities of compost
Compost can include any of the following products and more: grass clippings, leaves, vegetable food scraps, coffee grounds, black and white newspaper, printer paper, disease free yard waste, cardboard, vegetarian animal manure, wood shavings, and sawdust.
Another way to use compost is in a compost tea. Compost teas are liquid organic supplements for your plants and gardens that are made by steeping aged compost in water. In fact, compost tea is so rich in nutrients that it even doubles as an organic liquid fertilizer for your plants!
Compost tea is a great addition to your plants because:
- It increases plant growth, resulting in prettier, healthier, and bigger plants and vegetables.
- It gives nutrients to both plants and soil quickly because it is in liquid form.
- It introduces organisms that are beneficial for plant and soil health.
- It helps to lessen diseases that can occur in plants because its natural microbes destroy disease-causing microbes, and the tea itself helps to dissolve toxic pesticides or other chemicals in the soil.
- It is a completely organic and non-toxic replacement for harsh chemicals normally used on plants and gardens.
You can make your own compost tea very easily! Just follow these six steps:
- Fill a bucket 1/3 of the way full of mature compost.
- Add water until the bucket is full.
- Let it sit for 3 to 4 days. Make sure to stir it every so often during this time.
- Strain the mixture through a porous material like burlap or an old shirt into another bucket. You can put the solids that remain back into your compost pile or into your garden.
- Add more water to the remaining water until it is the color of weak tea.
- Use on your plants immediately for best results. If you are putting the tea on potted, young, or delicate plants, dilute the tea a bit more, so it isn’t too strong.
An In-Depth Look at Mulch
Mulch has one main job – to improve soil conditions. It can be organic or inorganic, and it is used by gardeners and farmers in order to help their soil keep its moisture, suppress weed growth, regulate its temperature, and make gardens look more attractive. One added benefit of using organic mulch is that it helps to increase the soil’s fertility.
Organic Mulch
If you choose to use organic mulch, you must be prepared to replace it from time to time because it does decompose. One rule of thumb when dealing with organic mulch is that the drier and woodier the mulch is, the longer it will take to decompose – but the fewer nutrients it will give back too the soil. This can help you decide what kind of organic mulch you want to use.
Types of organic mulch you can use include:
- Bark – Bark mulches are great to place around trees, shrubs, and in garden beds that don’t require much digging.
- Compost – You have to make sure that compost mulch is weed-free before placing it. This mulch is good for placing a light layer around your plants in the growing season to help give them a boost of nutrients.
- Grass Clippings – Grass clipping mulch is only really suited for remote areas of your garden where you just need to prevent weeds from growing. This mulch decomposes very fast and can sometimes have an unpleasant look and odor as it decomposes.
- Newspaper – Newspaper mulch is becoming more and more popular. Black and white newspaper is shredded and placed onto the garden bed. The newspaper is great for holding in water, preventing weeds, and regulating soil temperature. Newspaper mulch is also very good for jump-starting a brand new garden.
- Shredded Leaves – Leaf mulch can be used anywhere, and it actually encourages earthworms to move into your soil, which helps with soil aeration and plant growth. Leaf mulch can become matted together and start to repel water, so you do need to watch it and rake it to loosen it up if this happens.
- Straw and Hay – Mulch made from straw and hay is incredibly popular for vegetable gardens. The straw will last the entire growing season because it decomposes slowly. This mulch also brings in spiders and other good insects that help keep pests away from your growing vegetables.
Inorganic (or Synthetic) Mulch
Inorganic mulch is a suitable mulch choice for those who want the benefits of mulch without the added fertility to the soil and maintenance of the mulch. For instance, choosing a synthetic mulch will still help suppress weed growth, hold in water for your soil, and regulate the soil’s temperature – but it won’t decompose. Therefore, you won’t need to replace it like you do with organic mulch.
Types of inorganic or synthetic mulches that you can use include:
- Plastic or Landscape Fabric – These synthetic mulches are great for plants that don’t need to be fertilized often, like foundation plants, shrubs, and trees. Be aware that plastic gets very hot in the summer and can kill good things in the soil – including plant roots – so you have to be sure to water your plants regularly.
- Gravel and Stone – Before deciding on using gravel or stone as mulch, know that they are hard to remove. You want to make sure that you definitely want to use them. They are great for gardens or flower beds that need good drainage and additional heat.
When you are deciding on your mulch, it is important to consider the plants that are growing in the area you want to place mulch in. If your plants are ones that need as many nutrients as possible, organic mulch is probably best. For stronger plants, trees, and shrubs, inorganic mulches can be a suitable choice.
An In-Depth Look at Fertilizer
Simply put, fertilizers are materials that are added to plants in order to give them nutrients that are essential for optimal growth. They can be either organic or synthetic, but they will always deliver nutrients.
Some of the different fertilizers available include:
- Single-nutrient fertilizers
- Multi-nutrient fertilizers
- Compound fertilizers
- Organic fertilizers
- Liquid fertilizers
- Solid fertilizers
- Slow or controlled-release fertilizers
Single-nutrient fertilizers include just a single essential nutrient for the plants. Multi-nutrient fertilizers combine nutrients and deliver multiple nutrients to the plants. The nutrients used in these kinds of fertilizers include nitrogen, potassium, and phosphate.
Compound fertilizers are similar to multi-nutrient fertilizers in that they combine nitrogen, potassium, and phosphate, but they are different from them because they usually involve chemical reactions between the components.
Organic fertilizers are made from organic waste only. They get their nutrients from the decomposed organic wastes, and they can be bought from a store or created by the farmers themselves.
Liquid fertilizers are less common than solid fertilizers. They are typically made from ammonia, ammonium nitrate, or urea that are diluted with water in order to be sprayed directly onto the plants. The benefit of liquid fertilizer is that it is easy to apply and can cover lots of area very quickly. Sometimes, liquid fertilizer is added to the irrigation systems of crops – this is called fertigation.
Solid fertilizers comprise about 90% of all fertilizers used. They are placed directly onto the soil around plants in order to introduce the nutrients into the soil. The most commonly used solid fertilizers are urea, diammonium phosphate, and potassium chloride.
Slow or controlled-release fertilizers are not often used because you have to be very careful not to overfertilize your plants. While they are more difficult to manage, they are better for the environment and less likely to contaminate water supplies. Most slow release fertilizers are made with urea. Controlled-release fertilizers are packed within a capsule that slowly degrades and releases the fertilizer.
An In-Depth Look at Soil
Soil is one of the most interesting and complex parts of the earth, and it’s often overlooked because it stays under our feet. In fact, soil has so many parts and peculiarities that soil science is split into two different disciplines – edaphology, which studies the soil’s influence on living things, and pedology, which focuses on the formation, description, and classification of soil as it occurs in nature.
Soil has different types and various layers. You can grab soil from two spots across the street from each other and see two completely different soil compositions. Soil can be some of the newest formations on earth, and you can dig deep into the ground and hold soil that is from as far back as the Cenozoic Era that occurred 66 million years ago.
The four types of soil and their characteristics are:
| Soil Type | Characteristics |
| Sandy Soil | – made from small particles of weathered rock like granite, limestone, and quartz – not good for growing plants – very low nutrients – doesn’t hold much water – good for drainage systems |
| Silt Soil | – made up of smaller particles than sandy soil and larger particles than clay soil – holds water better than sandy soil – usually found by rivers, lakes, and other bodies of water because it is transported by water currents – the most fertile of all the soil types – commonly used to improve soil fertility in agriculture |
| Clay Soil | – made of very small particles that pack tightly together and leave very little space for air – great water storage – sticky to the touch when it is wet but very smooth when it is dried – the heaviest and densest of all the soils – does not drain well – does not provide much room for optimal root growth |
| Loamy Soil | – a combination of sand, silt, and clay that gives the benefits of all three soils – retains moisture and nutrients well – best soil to use for farming – also called agricultural soil – has higher calcium levels and pH levels because it is inorganic in origin |
In addition to soil having different types, it is also comprised of many layers – called horizons. There are 6 soil horizons – most soils have at least three of them, some soils have all layers, and some include an organic layer. The horizons are referred to as O, A, E, B, C, and R in order of their appearance and according to how often they are present in different soils.
| Horizon Name | Description |
| O – Humus or Organic | consists of mostly organic matter like decomposing leaves and grass – can be a thin or thick layer, depending on the soil type – not present in all soils |
| A – Topsoil | – consists of minerals from the parent soil material and some organic matter – the layer where plants and other organisms live – present in all soils |
| E – Eluviated | – consists of a concentration of sand and silt from resistant materials like quartz – does not include any clay, minerals, or organic matter – not present in all soils – most often found in old soils and forest soils |
| B – Subsoil | – full of minerals that move down from A and E horizons -present in all soils |
| C – Parent Material | – the original deposit that the soil developed from – present in all soils |
| R – Bedrock | – a solid mass of rock, usually basalt, granite, quartzite, sandstone, or limestone – creates the parent material for some soils that have a bedrock close enough to their surface to weather – not present in all soil |
Soil has been studied by humans since the Greek historian Xenophon wrote of the benefits of adding manure to crops to help them grow between the years of 450 and 355 BCE. Soil has been studied since ancient times because it is directly connected to a human’s need to feed himself and his livestock. Improvements in agriculture and advancements in soil science are still happening today.
In Conclusion
Compost, mulch, fertilizer, and soil are all very different from one another, but, somehow, they all come together to create the perfect environment for plants and crops to thrive. These four components work together to make gardening and agriculture possible, helping humanity continue to sustain itself while bringing beauty to the world as well.