We all use mulch to suppress weeds and make the landscape more attractive. But is mulch good for the soil? And does it affect soil pH?
Well, mulch is more than a protective layer for your soil. It can retain moisture in the soil, keeping the plant’s roots cool. In addition, mulching can prevent frost heaving in winter.
In this article, we’ll tell you everything you need to know about mulch and how it affects your soil. We’ll also tell you about mulch types and which is best for your garden.
Yes! Mulch can improve soil quality in many ways. Let me tell you about them.
Mulching can suppress weed growth in your soil in two ways. For starters, it can act as a physical barrier, depriving weed seeds of light.
In turn, the weed seeds won’t be able to germinate.
There’s also the fact that bare dirt is the perfect environment for weed seeds to germinate.
So, by mulching your soil, you’ll stop most seeds from reaching it in the first place.
After a while, organic munches start breaking down. That can provide your soil with a lot of nutrients and organic matter.
However, that only applies to biodegradable, organic mulches.
There are many types of inorganic mulches, like rubber and plastic. These types don’t break down, meaning they don’t provide your soil with any nutrients.
Fun Fact: the word “mulch” is derived from the German word “molsch,” which means easy to decay!
Plants need an adequate level of moisture in the soil to grow healthy. Otherwise, your plants will become stressed, and might even get sick. That’s why losing moisture can become a problem, especially in hot regions.
To retain moisture, you’ll need a material that covers the soil but also allows it to breathe.
That’s where mulching comes in handy. Although it’s typically a thick layer, it still allows your soil to breathe, while retaining a good amount of moisture.
You can think of mulch as a protective layer that also feeds your soil. Let me tell you how.
After spreading your mulch layer, it acts as a blanket that retains moisture. So, your soil can store water more effectively.
As a result, the soil will remain loose and won’t dry out too quickly.
Not only that, but since it covers your soil, it leaves no room for weeds to grow. That means your plants can grow healthier.
However, it’s worth noting that different types of mulch may affect your soil in different ways.
Let’s check out popular types of mulching materials and how they can affect your soil.
Shredded wood is one of the most popular mulches because it’s one of the better-looking mulches that don’t ruin your garden’s allure.
Shredded wood also can last longer than most decorative mulches. In addition to that, it breaks down slowly, depending on the wood type.
Therefore, it’s perfect for flower beds rather than vegetable gardens, as it provides the flowers with the nutrients they require.
However, the problem with this mulch is that if you use fresh wood, it can slightly affect the nitrogen levels in the soil. So, you should use aged wood chips.
Ideally, you should age your wood chips for at least one year to ensure they won’t have any reaction with your soil.
Are you looking for an easily available mulch? Well, leaf mulches will be perfect for you.
Leaf mulches are good because they’re cheap and nutrient-rich.
You can even produce your own mulch, but it’ll need a bit of patience as you’ll need to dry the leaves first.
The problem with leaves is that if they’re damp, they might rot. On the other hand, if they’re too dry and light, the wind might easily blow them away.
More importantly, you shouldn’t use leaves from chestnut and oak trees, as they contain high amounts of tannins, so they might damage your soil.
After mowing your lawn, you can use the grass cuttings for mulching! Grass clippings are cheap and easily available, but unfortunately, they only last a few weeks.
Despite that, grass clippings are ideal for mulching, as you can use them in garden beds and around trees.
It’s worth noting that you shouldn’t apply grass clippings in thick layers because they might clump together and damage your soil.
If you have vegetable gardens or newly seeded lawns, straw is a mulch material you should consider.
In addition to keeping your soil moist and providing it with nutrients, straw can attract beneficial insects.
On top of that, it partially reflects sunlight from below, providing your vegetables with an extra dose of light.
However, straw isn’t the best option for decorative gardens, as it might not look appealing.
It’s worth mentioning that straw is ideal for dry gardens only. In wet gardens, straw can decompose quickly, which can increase the risks of fungi spreading under the mulch.
The answer to this question can be complicated, as it depends on the type of mulch you’re using.
In some cases, organic mulch materials, like pine bark and fresh wood chips, can become low in nitrogen. The microorganisms responsible for decaying low-nitrogen organic matter need to obtain nitrogen from another source.
So, they take nitrogen from the soil. In that case, nitrogen is temporarily tied up in their bodies.
After the food runs out, the microorganisms will begin to die. Then, the nitrogen they absorbed goes back to the soil.
You can think of it as if they borrowed a small amount of nitrogen from your soil for a short period. However, during the time they’re using it, your soil will be temporarily low in nitrogen.
In some cases, that can lead to pale leaves and stunted growth, which are symptoms of nitrogen deficiency.
Luckily, not all types of mulches borrow nitrogen from the soil.
In addition, you can compost the organic mulch before using it to avoid that.
By doing that, you’ll allow the decomposition process to take place before adding the mulch to your soil.
You can also add nitrogen-containing fertilizer to mulch materials that consume nitrogen.
All in all, you shouldn’t worry too much about nitrogen tie-up, as it’s a normal part of the process.
Yes. Mulch can be highly beneficial to clay soils.
Soil clays don’t typically retain moisture for a long period. So, mulch can slow down water run-off, allowing the soil to store water for longer.
In addition, it can keep the soil cooler and suppress weeds. On top of that, it provides the soil with various nutrients.
Generally, mulch doesn’t significantly alter soil pH. In addition, it depends on the type of mulch.
Some types of organic mulch, like wood, can cause temporary changes in pH. However, the pH change will mainly be in the decomposing mulch layer. So, this will have little effect on the underlying soil.
Some types of mulch, like hardwood, can release alkaline substances into the soil. However, they won’t make your soil alkaline.
Mulch can increase or decrease soil temperature, depending on the type of material you’ll be using.
Some types of mulches reduce evaporation and act as a cover for the soil, leading to a cooling effect.
On the other hand, some mulches increase soil temperature when required. Most of these mulches are inorganic and transparent to allow sunlight to go through them and reach the soil.
So, you need to do your research and make sure to pick the right type of mulch, depending on your soil and the plants you’re growing.
Yes. Mulch can keep the soil moist, as it acts like a barrier, reducing moisture loss. In winter, mulches also allow rain to reach the soil, which helps keep the soil moist.
So, is mulch good for the soil?
The answer is yes! Mulch is generally good for the soil.
That’s because it suppresses weeds, which can be harmful to the soil. In addition, they help the soil retain moisture.
On top of that, after decaying, organic mulch can provide your soil with many nutrients.
However, keep in mind that it all depends on the type of your soil and the requirements of your plants. Choosing the wrong type of mulch can do more harm than good.
Therefore, make sure to do your research and pick the right type of mulching material for your soil.
Ben has a bachelor’s degree in construction engineering. When not constructing or remodeling X-Ray Rooms, Cardiovascular Labs, and Pharmacies, you can find him at home with wife and two daughters. Outside of family, He loves grilling and barbequing on his Big Green Egg and Blackstone Griddle, as well as working on projects around the house.
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