How Much Will Topsoil Sink: Depressions, Potholes and General Uneveness

It happens to new gardeners all the time. You fill a bed or fix a lawn patch, and after you water, you realize you didn’t know how much topsoil will sink. Now you’re left with a mess that isn’t level. What can you do? Depending on the blend, your topsoil may sink substantially. Luckily there are ways to account for that sinkage, and you can minimize it as well. By adding more than you thought you needed, the settling will help even things out for you. However, you can also tamp it down to remove some of the air inside that soil layer so it doesn’t dip as far. I’ll walk you through how to find good topsoil and how to use it, so you get a smoother surface. Soon you’ll have the professional-looking garden or lawn you always wanted. It’s easier than you think. I’ll show you how it all works.

How much will topsoil sink? About a third of your topsoil will settle or sink. You can help minimize this by tamping down the soil in layers to press some of the air pockets out, but there will always be some settling. Well tamped topsoil may only sink an inch or so, but it will always be lower after watering than it was when you first put it in. 


Does Topsoil Need To Be Compacted

Topsoil will not sink as much if it is properly compacted. There are two methods, rolling and manual or stomping it down. Either way, you need to make sure you have well-draining soil underneath your topsoil. Otherwise, your grass won’t grow.

A heavy roller isn’t something everyone has easy access to, but you’re in luck. Walking over topsoil is usually sufficient to do the job. You can also grab a board and some rope to get a nice even compacted layer.

When you finish, bring in more soil and repeat the process. Since soil can settle up to one-third of its initial height, this will prevent sunken spots in your lawn. Remember to add water and let it settle completely before you sod over.

Don’t be surprised if you need to add a bit more soil after you dampen it. The water and soil weight helps press out some of the excess air trapped between dirt particles. However, it would help if you remembered not to compact things too far, or the grass roots won’t be able to dig in.

Choose reliable topsoil like Scotts Company Earthgro Top Soil from Amazon. Scotts is a well-known and trusted brand in gardening. In fact, O.M. Scotts was founded in 1907, and it’s been making outstanding lawn and garden care products for over a century. This forty-pound bag of natural Earthgro will cover a lot of uneven spots. Plus, there’s over a century of research and excellence in every Scotts product. Find out more by clicking here.  


How Thick Should Topsoil Be

Topsoil is an essential layer everywhere, but the thickness depends on where and how you’re using the topsoil. Now that you know how much topsoil will sink, it can help you calculate your layers. Garden beds don’t need as much as your lawn.

Under your favorite grass, you want at least six inches of compressed but not completely solid topsoil. For garden beds, a good six inches is fine, but you can do with just three. Especially when you have raised beds, you need to leave space for topsoil and mulch.

When making space in a garden, remember to leave space for well-draining soil, topsoil, and mulch. The mulch layer on top breaks down and provides some nutrition over time, but it also prevents weeds from germinating as the seeds get into your beds.

Calculate How Much Topsoil You Need

Calculating topsoil in square or rectangular areas is relatively easy. You measure two sides and multiply those numbers. In the case of a rectangle, you need a long side and a short side, but squares have even sides, so it doesn’t matter.

Round up to the nearest foot since a little extra dirt is better than not having enough. Once you know the square footage, you can multiply by the height you need. It’s okay to measure in inches. I will show you how to get cubic feet at the end.

For six inches deep, you need to multiply by half a foot or 0.5 feet. If you measure in inches, then multiply by three or six inches accordingly. Soil is sold in cubic feet, so if you used inches, you need to divide your final total by twelve and round up to the nearest whole foot for a cubic measurement.


Does Topsoil Harden

Not all topsoil hardens. If your topsoil sinks and hardens, you may have poor-quality topsoil. Luckily, you can buy more and mix in better topsoil to get a consistency that drains and does not clump. Alternately, you can always dig out the bad topsoil and start fresh.

When the top layer of earth in your yard has too much clay, sand, or even rocks, it won’t give you a healthy lawn or garden. The problem with hard or clumpy topsoil is that it blocks plant roots.

Furthermore, bad topsoil may not allow drainage. When soil doesn’t drain, it can pool on the surface resulting in puddles and ultimately root rot for your garden or lawn. It is crucial to get good topsoil.

Soil that’s too sandy won’t hold water. Just like soil with too much clay, this isn’t good for plants because they can’t drink as the water passes right through. Mulch can disguise these problems in garden beds, so move the mulch aside and check if your plants aren’t healthy.

Topsoil is the top layer of soil. This part is often inert unless you buy a custom blend with organic material and soil microbes inside. On the other hand, Mulch provides shade, prevents excess water evaporation, and biodegrades over time to help feed your plants.

When you’re looking for a less weighty solution, Scotts Premium Organic Top Soil from Amazon is perfect. With no biosolids, you get clean, safe soil for your lawn and garden beds. The lighter blend is great for raised beds and indoor plants because it won’t weigh them down as a traditional blend can. Peat moss helps with drainage. To read the reviews yourself, click here. 


Should I Tamp Topsoil Before Seeding

There are several steps you should take before seeding. Hopefully, your topsoil has already sunk by the time you have reached the planting stage. If not, now is the time to level it with more topsoil. Tamping comes later after the grass seed is in.

For a healthy lawn, you may want to turn peat moss into the soil first. Since this unique moss holds as much as twenty times its weight in water and releases it back slowly, it’s an ideal soil amendment. A roto roller is best for large lawns since it will mix the peat moss up to six inches below the surface.

Next, run a rake through any areas where you plan to seed. Doing this helps turn over any stones and ready the soil for seed. Good grass seed can be expensive after all. You want it to grow without needing to over-seed.

After you have raked, you should roll or manually tamp the soil down. Your seeds don’t want to be packed in cement-like clay, but they also don’t need to be sitting in loose fluffy dirt that is more air than nutrients. By taking the time to pack the dirt before you plant, you will have a better germination rate.

This step helps the topsoil hold enough water for new seeds to sprout and grow. Remember that you only need to go over things about once. Too much tamping will create a dense, hard-to- penetrate layer where new baby roots can’t spread, and leaves can’t break the surface.

More importantly, tamping makes sure the seed is in contact with the dirt. This is essential to help seeds sprout. Without this step, you could lose more seed than you grow in loose topsoil. Plus, loose topsoil will blow away in the wind.

Tamp the best with a bag of Scotts 0.75 cu ft. Premium Topsoil from Amazon. This rich blend is great for gardening or filling depressions in your lawn for that smooth, perfect look. This type of topsoil packs down well for a nice, finished look. Have Amazon deliver to your door by clicking here.


Final Thoughts

No one wants a messy, uneven yard, and unsightly topsoil sinkage can spoil all your hard work. Sure, some gardeners like a messy look, but for most, an even bed or smooth expanse of grass is the best to look at. You can get to that level easily. Make sure you tamp it down and add a little more dirt on top if things still don’t look right when you’ve watered.

With a third of your soil settling, it can get frustrating, but it’s easy to do the math. Take your number of inches deep and divide by three. Then multiply that number by four, and you know how deep it needs to be to settle properly. Or, tamp things down a layer at a time instead of filling up garden beds all at once for less sinking.

Patience and gardening go hand in hand. Soon, you’ll have a handle on how low your topsoil sinks, but remember that switching brands may mean a slightly different effect.

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