Buying topsoil seems like one of the easiest purchases around. Its everywhere…everyone knows what it looks like…and it should be dirt cheap, right?
Nope.
Topsoil is amazingly expensive. Topsoil quality is surprisingly variable. Making topsoil is simple, but to do it on a commercial scale is time consuming, capital intensive and full of unforeseen problems.
I’ve been involved in soil related commerce for 25 years. I can’t recall how many times a customer calls and after hearing the price, there is a pause and a sudden cry, “But I only want dirt!”
Dirt is probably what the customer doesn’t want. If you are shocked by the price of topsoil and can’t figure out why it is so expensive, you only have to look as far as your home. If you are calling a company asking for topsoil, then it’s because you realize the soil in your own backyard or the pile of file in you’re neighbor’s backyard isn’t the quality you want.
If all you want is dirt, then it’s all around. Get your shovel, hop in your pickup and dig it up somewhere. You can find someone who wants to get a hole dug or a mound removed. At around 15 lbs. a shovel full, 160 shovelfuls to a cubic yard and one or two cubic yards in your pickup truck per load (depending on how flat you like your tires to look), the dirt becomes increasingly precious. Suddenly, that landscape yard on the other end of town that wants to sell topsoil for $30 a cubic yard has a pretty good deal. Of course, if you are putting your gym fees on hold while you do this project, then it might not be such a bad exercise alternative. Of course, we haven’t discussed the issue of quality yet.
First, good topsoil is approximately 50% air space. That may be hard to believe especially when one holds up a hard piece of dark, dry clay. Yet, that’s exactly what it is unless it has been compacted severely. That 50% air space shouldn’t be all air space unless it’s bone dry. Ideally, half of the air space is filled with water. Specifically, good topsoil is 50% soil, 25% air and 25% water. It should be crumbly and smooth to the touch or what any decent farmer knows as good tilth.
Topsoil should be friable
No, that doesn’t mean seasoning it on the grill with a steak. Friable is…well, let me explain…Topsoil is composed of various portions of sand, silt and clay. Sand, silt and clay are just different measurements for fine particles of weathered rock. Too much sand and the soil won’t hold moisture. Too much clay and as it dries and hardens, it starts to mimic the days it was a rock. If these components (sand, silt and clay) are in equal proportion, that’s loam. That’s probably the best soil to work with. With a little extra sand, it becomes a sandy loam or with a little more clay, it becomes a clayey loam. These and any other variations are also good.
What you want to stay away from are mixes that are heavy in sand or clay. The best way to tell is to grab a handful and feel it. If it bunches up into a ball there is too much clay. If it falls apart, there is too much sand. If it folds up into a crumbly, smooth mass that slowly comes apart in your hand, then that is just right. Of course, this assumes a moderate amount of moisture…remember the 25% above? Anyway, that’s what friable is.
Topsoil should be partly organic
No, I don’t mean organic like pesticide-free vegetables. I mean organic in the original sense of the word. It needs organic material like humus. Humus is a dark colored organic material decomposed to a stable level. It is also good to have partially decomposed plant matter and a stick or leaf here and there too. Good naturally occurring topsoil has 1-5% organic content. In some places, like near peat bogs, the organic matter can exceed 20% or more. Generally, when a soil gets over 20% organic content it’s called an organic soil. If a soil has less than 1% organic matter, then it’s not topsoil, but subsoil. And that’s not for growing.
The way I figure it is if a customer wants to buy topsoil, then they should buy something better than what they can dig up in a farmer’s field. So I like my soil blends to have more than 5% organic matter. The soil stays fertile longer that way, and the customer keeps a smile longer as well. In some cases soil with lots of organic matter is good, especially with pots. While in other cases soil with less organic matter is better, as when it’s going to fill a deep hole. Generally, a good portion of organic matter is best. A soil with lots of organic matter will have a dark color to it, either black or brown. This doesn’t mean that every soil that is black or brown has organic matter. However, if it isn’t black or brown, then it probably doesn’t have much organic matter, and it’s best to steer clear of it.
One of the best sources of organic matter is compost. Compost varies considerably, however. It shouldn’t be coarse or unduly hot. Almost all compost will have some heat. It isn’t economically feasible for a composter to compost until his material is completely decomposed. That could take a year, and the compost would be very pricey.
Topsoil should be fertile and balanced
This means is that it should have lots of nutrients, and the nutrients should be relatively balanced to each other. There are the major nutrients or macronutrients as they are usually called. These are nitrogen, phosphorous, potassium, calcium and magnesium. Generally if these are okay, then your plants are okay, but there can be problems with the micronutrients, such as iron, zinc, manganese and copper to name a few, but all of these only need a trace amount in your soil, so they are usually easy to fix. It’s probably good to ask for a soil analysis or at least a chat with the soil salesperson about the soil fertility. If they haven’t done a soil test, then they either don’t know what they are making or they know too well what they are making and are trying to hide it.
Sometimes I do soil tests on my finished product. On other times, I’ve done an analysis of all the ingredients and added the proportions together. The first is the easiest for the customer to understand. The second is the best way for the soil manufacturer to create a good soil. A soil test doesn’t have to be up-to-date, just as long as the ingredients haven’t changed dramatically since the last analysis. Sometimes I take the samples to a soil laboratory for a certified report. I’ve also done the results myself in my own lab. As long as it’s down competently, a little variation is acceptable.
If you do see a copy of a soil test, it should have suggested values next to the actual numbers. Most soil labs use suggested values from naturally fertile soils and plug them here. I find that in most landscaping uses these numbers are woefully inadequate. Yes, the plants will do fine for a few months, but then they start to look weak and need fertilizer. If you are paying $20-30 a cubic yard for soil, you should get something that lasts longer than a couple of months.
If the nutrients start exceeding 200%-300% of the recommended value, then there is a danger of plant damage. This is especially important if the nutrients get out of balance. The major nutrients should be roughly balanced with 1 part nitrogen, 2 parts phosphorous, 8 parts potassium, 30 parts calcium and 6 parts magnesium. Of course, these levels still have to be high enough to be fertile. This balance is not a hard and fast rule. Some plants want more of one nutrient than another does. For example, you can pour nitrogen on lawns, and they will love it. These ratios can have a significant amount of variation and everything will be fine. Things start to go haywire when the potassium exceeds the calcium or the magnesium is the same level as the calcium…or, well, you get the idea. If the soil company doesn’t have a good reputation or they can’t answer a few questions on fertility, then call the next company.
Another thing to consider about nutrient balance is the organic content of the soil. The organic matter is a nutrient bank for the soil to draw on over time. This is another reason the organic matter needs to be high, especially for landscape use. You can always put more organic matter into next year’s vegetable garden. If you plant a rose garden or a lawn, getting organic matter back into the soil isn’t as easy. The other advantage with organic matter is that it buffers toxins and nutrient imbalances.
There’s one more thing to look for and that’s pH. Usually a soil around 7.0 is what you want. However, if you have rhododendrons or other acid-loving plants, you’ll want a pH around 5.5, and if you have drought-resistant plants, then you probably want a pH over 7.5. The pH is highly important as it affects how a plant uptakes nutrients.
Topsoil should be screened
Alright, I guess it doesn’t have to be screened. Still, I always figured that if you’re paying good money for it, it’s nice to have the large sticks, rocks and clumps out. Also, if it is a blended soil and it isn’t screened, then it probably was mixed with a loader. Although some loader operators do a great job mixing, others are thinking about the beer after work, and it won’t get mixed well. A blended soil is usually a mixture of soil and organic matter. Sometimes it’s easy to notice poorly mixed soil. A clump of manure is a dead giveaway. Other times you won’t ever notice, but will wonder why the shrubs in the corner of the yard didn’t do as well. If it’s not screened, you should ask why not? If a soil is screened, it most likely will have been agitated enough to get a thorough mixing.
Topsoil should be nearly weed-free
It’s hard to guarantee a 100% weed-free soil. If it’s a sterile material, maintained in a sterile environment, then immediately delivered to the customer, then it’s possible. Most of the soil products purchased in bags fit this category, but the bulk soil dealers, like me, do most of our work outdoors. I don’t know if you’ve noticed it, but there are lots of weeds in the outdoors. It doesn’t take too many weeks for a sterile pile to have some weed seeds blown onto it from a few gusty days. I like to guarantee a 99% weed-free soil, just because if I say 100%, then I know I’m lying to someone every once in a while.
Anyone who blends soil should make a weed-free soil. The organic material should be composted or come from a weed-free source, like sawdust. The soil should not be the upper layer of topsoil, but either topsoil below the top of the ground or subsoil where there are no weeds. Yes, I know that sounds strange. Isn’t topsoil supposed to come from the top of the ground? Yes, but a good soil manufacturer will take soil below the top of the ground and mix organic material with it to make good, weed-free topsoil. If the soil company won’t guarantee that it’s 99% or 98% or 90-something percent weed free, then don’t buy it. Bringing new weeds into your yard is always a mistake.
Ask for the recipe
Yes, that’s the topsoil recipe. If it’s a blended soil, the company should be able to tell you in general terms what they put in it. Some places don’t like to go into specifics for trade secret reasons, but any vendor can give you the general information. If they don’t, it should be a red flag. Pepsi and Coke may have their secret formulas, but the major ingredients are printed on the side of every can. You should at least expect the same information from a soil dealer. Even if its not a blended soil, the company still should tell you what type of soil it is—loam, sandy loam, etc.
One more thing-the organic material should be either composted or nitrogen fortified. If someone is using organic material that doesn’t fit these categories, then be suspicious. Okay, there are exceptions-coir (coconut husks), rice hulls or many other organic materials. If a soil manufacturer uses these products, it should be with other organic material that is composted or nitrogen fortified. Most amended soils use manure or yard waste and these must be composted to control disease and prevent soil problems.
If it smells…
Topsoil shouldn’t smell unless it has the same earthy odor as when you grab a handful off a forest floor. Offensive smells can come from non-composted manure, yard waste or other chemicals. If it smells, don’t even ask questions, just walk away.
One of the biggest soil myths to dispel is color. Yes, dark soil does look good and it often is good. Seeing good color is a good place to start when evaluating soil. However, the soil can be dark and not be good topsoil. It might have weeds or it might be contaminated. There are even a few tricks to making a light color soil dark and not adding any organic matter. But by asking the questions I’ve pointed out, you can determine how the quality of the topsoil.
The last thing to evaluate is a company’s reputation. There are lots of companies selling topsoil. Those with a good reputation are doing something right. And if they won’t give you a guarantee, think long and hard before buying. I always tell people if you have a problem let me know. I want to know before more people have the problem. This isn’t a perfect world and even good companies make mistakes. Over the years, I’ve given refunds, free loads of soil and many apologies, even during times when I knew the customer to be wrong. A company has to stand behind its product. If it won’t give a guarantee, then something is wrong with the product.
If you want to garden successfully, you need to start with the soil. It’s the foundation for everything else. If you take your time finding the right soil, you’ll prevent many future problems.
