The Composition of Good Soil

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Hey everyone. I’ve spent ample time gardening with less than adequate soil from seasons of growing plants in the tough Phoenix climate. At first, I thought it was impossible to grow anything with such horrible conditions. The truth is very few people are blessed with the kind of soil that’s talked about in gardening books and magazines.

As a gardener you have to keep working at your soil until it provides the right amount of nutrition and support for your plants. It’s often times a long and arduous journey but the rewards are well worth it. As your soil improves so will the yield and health of your plants. This  leads to a garden that is more resistant to insects and disease. I’ve created this post to show obtain good soil over time.

If you’ve already started a garden you might already be aware that developing good soil is no quick feat. You suddenly become faced with a myriad of terms you might have never encountered. Soil can be well-drained, loose, rich, loamy, dry, water-holding, humusy, chalky, or silty among many other names. They all really mean the same thing: it needs work. If you’re new to gardening I’ll spare you most of the terminology and classify soil into its three basic types: clay-based, sandy, and loamy . Let’s delve deeper into each type.

Soil

Sandy Soil

Sandy soil is made up of rather large particles of earth which are either smooth if you’re near a beach or angular if near a lake or quarry. It usually feels gritty and rough to the touch if you rub it between your fingers. Although not the ideal medium, it does have the benefit that the large particles which make up the sandy soil create plenty of air pockets and space for your plant’s roots. The downside is that it’s not very good at retaining any water or nutrients as these pockets of space are easily permeable and water quickly sinks deeper into the earth. Sandy soil is easily worked in the spring and will be your friend with plants that prefer good drainage.

Clay-Based Soil

This is the stuff I’m most used to seeing. It’s prevalent in dry climates like the Phoenix desert. This type of medium is in some ways the opposite of sandy soil. It is made up of very fine particles of earth that like to stack on top of each other. This leaves very little space for water, nutrients, and plant roots to penetrate. If you wet it enough it turns into goo and becomes quite difficult to work with. Clay soil drains very poorly and turns quite hard when left to dry. With a little bit of personal bias, I consider this the toughest soil to improve.

Loamy Soil

Loamy soil is the absolute best type of soil you could have for your garden. It’s right in between sandy and clay-based soil. The particle size and overall structure is spacious enough to allow air, water, and plant roots to penetrate with ease and holds the nutrients long enough for plants to absorb. Loamy soil drains relatively well and is a pleasure to work with. If you happen to have loamy soil in your garden consider yourself one of the lucky few. If you don’t, I’ll explain how to improve your soil in its current state through the use of organic matter.

Organic Matter

This element in your garden is what determines what type of nutrients your plants will absorb and is a major contributor to your soil structure. Organic matter is simply the decayed remains of plant or animal matter. This can be obtained by keeping a proper compost heap. I’ll soon create a detailed post on how to create and maintain several types of compost piles in your home and link back to it. For now let’s get back to organic matter as a whole and what it does for your garden.

As mentioned, organic matter is responsible for the majority of the nutrients and properties that are brought into your garden. It’s typically brought in while it is fresh and decomposes while sitting in your garden, meaning that eventually you’ll have to add more. Once your garden is well established, you probably won’t have to add anything to your garden except maybe once or twice a year. For an underdeveloped soil, it can be a good idea to add organic matter throughout a growing season. By doing so you’ll provide enough nutrients for your plants to grow and over time you will notice the composition of your soil start to change for the better.

Organic matter adds microscopic organisms that break down compounds in your soil. However, the most important property is its ability to retain water. By keeping water in the soil it can create spaces between tightly packed clay-based soils while filling in spaces and helping retain moisture in sandy soils. It’s a win win for either soil and eventually with the help of some microscopic critters your garden can bask in its good soil glory.

Before you get excited and start adding any decomposed matter to your garden, there’s a particular concept that you need to consider.

pH

pH is the measurement of the overall acidity or alkalinity of your soil. There’s a lot to be said about pH as it can affect the type of microorganisms that grow in your soil, the health of your plants, the quality of any grown food, and even,  once again, the composition of your soil. There’s many ways to maintain a proper pH balance as well as various methods of testing it, and I’ll be dedicating an entire entry on it and linking back to that article once it’s published. For now, it’s enough to say that pH is very important while we move on to another soil related gripe.

Drainage

Drainage is a very important and often underrated factor in soil composition. It simply refers to how well water gets soaked into and moves through your garden soil. It’s definitely one of the hardest characteristics to change in your soil, but you should pay attention to it for the well being of your plants.

Poor drainage can be noticed at the surface of the soil or just below the surface. On a rainy day pay attention to where water puddles in your garden area and try to keep in mind how long the puddle lasts. If the water lasts more than 4 hours it could cause your plants to have “wet feet”. Many plants tolerate this habitat poorly and will show the effects rather quickly. Since water accumulates at the plant roots, there’s no space for air to come in contact with your plants and provide essential gas exchange. If the plant roots are completely submerged for too long, the plants are likely to die from having too much water.

Improving Drainage

If your garden has poor draining soil, there are some things you can do to improve the overall conditions. An effective solution is to dig 2-4 feet of your planned garden site and fill it with sand or gravel. This will ensure that no puddles are made on the surface or anywhere near the surface depth. It’s possible that the soil will still have poor drainage in depths deeper than where you supplemented your soil but you decrease the risk by at least covering the surface.

A second option is to try to limit the amount of water that drains into your garden site. You can do this by building some sort of diversion ditch, dam, or dike. It’s really just a ridge of soil around the garden. The idea being that when water drains down from higher parts, it will run through the ditches which will divert water around your garden. This option doesn’t improve the drainage of your soil, but if you’re in an area with lots of rainfall it can prevent an awful lot of unneeded water from entering your garden area. Both of these options require quite a bit of work, but if you don’t have good drainage in your soil then you won’t have a healthy garden.

A third option which takes less work is using additives in your garden. There’s many things you can find online and at your local gardening store to add to your garden but the ones that I’ve had the most success with are perlite, vermiculite, and peat moss. You can usually find small bags of these supplies at your local gardening stores, but to get the best quality and price I recommend buying them online and getting it shipped.

Perlite

Perlite is a naturally occurring volcanic glass with great water retention properties. It looks like little balls of Styrofoam and is great for filling in spaces with water-holding matter. Perlite can be a good additive for your garden and can contribute to better drainage over time, however I’ve learned that it is most effective when used in a 1:1 ratio with soil. If you’re working with pots or small raised beds adding an equal amount of perlite to your soil can be very effective in improving drainage and creating quality soil to grow plants in. However, if you’re working on a large garden bed in your yard it can take a lot of perlite before you start to notice a difference. I tend to buy it in bulk and have no complaints with the product listed below. You can click here and check it out on Amazon.

Peat Moss

This additive is a naturally occurring substance that can work wonders for new gardens. It’s the decomposed remains of prehistoric plants that have been compressed at the bottom of bogs and swamps. It literally takes millennia for nature to make more of this stuff. It’s a bit controversial to use because it’s not a renewable resource. If you want to use it you can find it readily available in many stores. This substance has a high nutrient density , retains lots of water, and is lightweight. Adding a generous amount to your soil can make a big difference. To cut down on costs I also buy this one which comes in bulk.

Vermiculite

A bag of this stuff can make the biggest difference when it comes to having good soil. Vermiculite is a hydrous phyllosilicate mineral which becomes heated and explodes kind of like popcorn. It’s lightweight, can hold more water than a sponge. This mineral will improve the water-holding capacity of both sandy and clay-based soils. I generally mix this stuff at a rate of 10-20% of my garden volume.

The great thing about vermiculite is that it lasts forever and becomes a valuable part of your soil for years to come. I consider it to be the best investment you can make for your garden. A note to keep in mind is that the more coarse and chunky it is, the better. Some garden supply stores sell very refined  almost sand-like versions of vermiculite which isn’t as useful. I recommend this one because of its coarseness and, honestly, it’s at a great price.

Good Soil

Onto the Nutrients

You’ve now learned about the overall composition of soil and how to deal with its problematic forms. Therefore it’s time to briefly cover fertilizers you can add to your soil. There’s quite a lot to say on this topic and I’ll keep it brief for the sake of this post.

If you shop around for fertilizers you might see a series of three numbers (5-14-2) next to the name of the product. Those three numbers symbolize the content and ratios of the nutrients in the fertilizer in the following order: nitrogen (N), phosphorous (P), and Potassium (K). In the future I’ll be adding a post covering these extensively and providing product reviews. For now let’s cover a few of the most common garden fertilizers.

Greensand

If you buy a bag of this stuff you won’t be surprised by what you find inside. It’s literally green sand and it works wonders for very dry clay-based soils. Greensand composed of a mineral found on the ocean floor called glauconite and releases potash, silica, and a bunch of other trace elements. It’s a great product compatible with organic gardening, although a little bit pricey. The biggest brand that provides this packaged material is Espoma and you can find it on amazon here.

Bonemeal

The source of this fertilizer can also be inferred by its name. Bonemeal is a ground up meal of animal bones. It’s commonly made from beef bones and is perfectly safe to use in your garden. It contains high amounts of phosphorous and is especially useful on flowering plants like roses, it helps them provide larger and healthier bulbs and flowers. Espoma is also a big provider of this stuff, and I’ve been using this one for a while now.

Bloodmeal

If you haven’t guessed already, this fertilizer is also exactly what it sounds like. It’s made up of dried up animal blood and typically derived from cows or other packaged meat animals. Bloodmeal is perfectly safe to use, and provides extremely high amounts of nitrogen for your plants. It’s particularly useful for growing green and lush plants. The only drawback is that it tends to increase soil pH so we can’t use it as abundantly as we might like. I also use the Espoma brand for this product and you can find the link here.

All-Purpose Fertilizer

If you’re new to gardening this fertilizer recipe will save you time and money:

  • 1 part bloodmeal
  • 2 parts bonemeal
  • 3 parts greensand
  • 4 parts composted leaves or peat moss

This should give you a 10 part fertilizer with an average of 2.5-5-2 NPK per part value. It’s not too concentrated but can help a new or established garden.

Now, if you want to combine this fertilizer recipe with some of the other compounds mentioned today we can create a pre-planned amazing soil mix.

Make the Best Soil

If you want to provide your garden with good soil in little time use the following formula. This mixture covers an area of about 16 square feet at a depth of 1 foot.

  • 2 bags – 6 cu. ft of peat moss
  • 1 bag – 4 cu. ft of Vermiculite
  • 4.5 5 gallon buckets – 3 cu ft. of sand
  • 4.5 5 gallon buckets – 3 cu ft of compost or your existing soil
  • 2.5 lbs of organic fertilizers

When these ingredients you’ll be able to fill a garden that is 16 sq ft at a 1 foot depth; or a 32 sq ft garden at a 6 inch depth. If you follow this combination you’re sure to notice a difference in the quality of plants grown in it. If it’s too much to add all at once, I’d recommend adding whatever you think your garden needs most. Building good soil takes a lot of patience and effort, but those are the virtues of a gardener.

Anyway, that’s it for now! I hope you enjoyed this post and found it informative. If you have any questions feel free to leave a comment below and I’ll get back to you. Cheers!

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