Mulching has a lot of benefits both for plants and for the topsoil as well, but how beneficial the mulch actually is, depends on what kind of mulch you use. Mulches are used for several reasons although, for the most part, their main use is as weed control and soil fertilizer. The most important factor which dictates how good a mulch will be for your plants depends on how you use it, if you make a thin layer of mulch then the benefits will be limited, if you make a thick layer then you could damage some of your plants.
The main benefits of mulch are that they protect the soil from erosion, feed the plants, and are extremely good at suppressing weeds. Keep in mind that organic mulches are far superior to inorganic mulches, as they decompose and help retain moisture in the soil. The most beneficial mulches for annual plants are grass clippings, hay, pine needles, and straw, and for perennial plants, the most beneficial mulches are wood chips and pine bark.
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There are two types of mulches, organic and inorganic mulches, both types do have several benefits but they tend to have some drawbacks as well. Organic mulches decay after a while which means that the trapped nutrients inside the mulch will be available for the plants to use. On the other hand, inorganic mulches are excellent at suppressing weeds but they do not decompose and feed the plants.
Some mulches like pine needles are also used to raise the acidity of the soil, although you should keep in mind that this is a temporary solution and you will have to keep on adding pine needles if you want to have a constant acidic soil. If you want to know the drawbacks of mulching then check out my recent article Mulching Disadvantages ( Top 9 Cons ).
Mulch Protects The Soil From Erosion
Erosion control is one of the main benefits of mulching, and if you have a couple of bare spots in your garden where nothing is growing then you can fix it by placing mulch on the bare spots. One of the main rules of permaculture is not to leave any bare spots in the garden or food forest, mostly because these spaces will be prone to growing weeds. A thick layer of mulch protects the soil from erosion by keeping the topsoil cool and moist where beneficial bacteria can thrive and plants can grow. If you want to know which mulches are the best for your vegetable garden then check out my recent article Best Mulch For Vegetable Garden ( Top 10 Mulches ).
Mulch Keeps The Soil Moist
Organic mulches are extremely good at retaining water, and this is extremely important for most plants. If you let the topsoil dry out then water will simply run off and not seep into the ground. Green organic mulches like grass clippings, fresh straw, and pine needles are excellent at retaining water. Plants that are grown in soil that is covered with mulch will be able to withstand drought, and some plants will grow without being watered provided the layer of mulch is thick enough.
Mulch Shades The Soil
Shade is extremely important for areas where there are little to no plants growing. Bare spots in the garden which are in direct contact with the sun will not allow anything to grow because the sun’s UV rays simply fry everything in the topsoil. Organic mulches which cover the soil in a thick layer will allow the beneficial bacteria and other microorganisms to come back, and in a matter of a couple of months, the soil will be good enough for plants to grow in. If you want to know how to fill a raised garden bed for as cheap a possible then check out my recent article How To Fill A Raised Garden Bed Cheap ( Top 13 Ways ).
Plants Can Grow Directly In The Mulch
The best part about using organic mulch is that you can directly grow plants in them, although not all mulches are good for this. For the most part, mulches that decay relatively fast like grass clippings, hay, and straw are a good growing environment for most plants. You do not even have to till the soil, just place a thick layer of mulch on top of the soil and plant your seedlings directly in the mulch.
Mulches Feed The Soil
As the organic mulch starts to decay they will release their nutrients into the ground, this acts as a fertilizer. Different types of mulches have different nutrients trapped inside them, and it is always a good idea to feed your plants with organic mulches which benefit them, like pine needles for blueberries and grass clippings for tomato plants. Keep in mind that inorganic mulches are only used as a weed barrier and they do not feed the soil, rather they deplete it by heating up the topsoil.
Mulches Suppress Weeds
Most mulches are used for weed suppression and the thicker the layer of mulch is the better it will be at smothering weeds. Both inorganic and organic mulches are excellent weed suppressors although inorganic ones like rubber and plastic mulches will be the best for suppressing weeds. Organic mulches are also good weed suppressors but you will need to de weed from time to time as some weed seeds will be able to germinate in the mulch.
Mulches Protect From Soil Compaction
Soil compaction occurs when the soil is already eroded and the soil particles are so close together that air can no longer circulate in the topsoil and water will not be absorbed. Soil compaction can happen to any type of soil but clay soil is extremely prone to soil compaction. By placing a thick layer of mulch on top of the compacted soil you will not only stop the compaction process but also fix it in the long run.
Once beneficial bacteria, bugs, and worms start feeding on the mulch they will slowly loosen up the soil with the holes they make in it. Just keep in mind that this process can take several years, depending on how compacted the soil actually is.
Mulches Attract Beneficial Organisms
Organic mulches attract beneficial organisms, like bacteria, bugs, worms, and even slugs. As these organisms start to feed on the mulch they will slowly start adding back the nutrients contained in the mulch to the soil. Basically, these organisms convert the mulch into an extremely good fertilizer for the plants. Just keep in mind that only organic mulches will attract beneficial organisms and inorganic mulches do not.
Mulches Aerate The Soil
Aerating the soil simply means that the air can circulate in the soil, and this is extremely important for the plants to develop healthy roots. The mulches do not directly help with aeration but they will attract worms which are extremely good for aerating the soil. This is why it is so important to use organic mulches as only these will attract worms and other borrowing bugs that help with the soil aeration.
Mulches Protect The Plants Form Frost
If you live in an area where winters tend to be fairly brutal then you can protect your plants with a thick layer of mulch. Organic mulches are excellent for protecting plants from frost although the best mulch for this job are wood chips. Wood chips tend to decay relatively slowly and this means that you only need to mulch in the fall and in the spring you will still have a relatively thick layer of mulch.
Mulches Regulate The Soil Temperature
No matter if you live in a hot or in a cold environment a thick layer of mulch will be able to regulate the temperature of the soil which allows the plants to grow tall and strong. During the summertime, the mulch will shade the topsoil thus reducing its temperature, and in the wintertime, it will trap the heat which is coming out of the soil thus protecting the plants from frost.
Mulches Stop Water Splashing On Leaves
There are some plants that are prone to diseases if they get their leaves wet, like the tomato plants. A thick layer of mulch will absorb the shock from the water droplets and dissipates it, which means that the water will not splash on the leaves of the plants. Just keep in mind that mulches like rubber, plastic, and wood chips tend to splash water as they are not that good at absorbing raindrops.
Mulches Increase The Soil Fertility Over Time
As the organic mulches decompose and feed the soil, the fertility of the soil will slowly rise. This happens because all the decaying plant matter will attract beneficial microorganisms and worms which will fertilize the soil with their poop. Just keep in mind that you will have to mulch the soil every year and it will take a couple of years until the fertility of the soil improves significantly.
As you can see mulches are extremely beneficial both for the plants and for the topsoil. Ideally, you should use an organic mulch as these have much more benefits than inorganic mulches like plastic and rubber mulches.