Soil Amendments for Raised Beds


The dirt! What are soil amendments and why are they important for raised beds?

Last year, even though we got a fair crop yield, we felt that the soil as it was newer and hadn’t “aged” yet, was limited in fertility. Soil fertility is very important – it’s a measurement of how nutrient dense overall what you’re working with.

The texture is important to measure too, soil that is too crumbly will not bode well, too sandy , same thing.

Checking your soil composition is a little bit of a science…There’s a “golden ratio” you want to strive for…It is about 40 percent sand, 40 percent silt, and 20 percent clay.

amending soil

When in Doubt, Test…

Veteran gardeners always have an arsenal of tests to check their soil’s composition.  First you can take a handful and compress it in your hand. If it doesn’t hold its shape and crumbles without any outside force, you probably have a little too much sand. If you poke the compressed ball with your finger and it doesn’t fall apart easily, your clay ratio may be too high.

If you’re still unsure, there is another approach you can take, it involves separating
each ingredient. Drop a cup or two of dirt into a jar of water. Shake the water up until the soil is suspended, then let it set until you see it separate into 3 different layers. The top one is clay, the next is silt, and the bottom layer is sand. This way you can easily gauge what your ratio is, and act accordingly to balance it out, if need be.

Now that you have some idea, time to look at some of the common fixes…If your soil sample has too much sand,  it’s best to add some peat moss or compost. If you’ve got too much clay, peat moss and sand together can help. Peat moss is a common addin that helps the new ingredients to infiltrate the mixture better.Of course, if you need any advice, you may be able to get some tidbits from the local nursery owner.

How much water is present in your soil is another factor.  having elevated beds in the first place helps keep the soil from absorbing too much water and helps maintain good drainage.

Some soils are very lacking in nutrients, so it’s up to you to build them up organically.  One to two weeks prior to planting, you should add a good amount of fertilizer to your garden. Let it sit up for awhile. About a week or two after planting, you should continue or a regiment to add fertilizer. In the first few weeks of being in the soil, the seeds you’ve planted are taking in all the nutrients quickly – but then when they run out, you’ve got to replenish it.

You can space out the length of time you add fertilizer after the plants’ growth is more apparent, as they will gradually need less of it. I use Miracle-Gro, which I mix in a gallon of water and dispense at the proper time.

amend raised bed soil

Check the Soil Ph

You should also be testing your soil’s Ph level….the “ideal” is about 6-7. If you’re not familiar with the Ph scale, anything from 1-5 is acidic, 6 is neutral, and anything above that is alkaline. You could probably get someone at the local plant nursery to do a test on a soil sample at a small fee. This could tell you all you need to know to go forward in improving the soil quality, what to focus on, and what not too, as if you change the ph level too rapidly, the plants could suffer shock.

It’s not too different from the test kits i would get for my aquarium, where there was an individual liquid product to test the Ph, nitrate, nitrite and ammonia levels.

6 or 7 is slightly acidic which is good to strive for. Most of the vegetable crops you’ll be planting will do fine at this baseline. If your ph is not optimum, sulfur can lower it – epsom salt (magnesium sulfate) dissolved is a good source, and lime or calcium-dense products like gypsum can elevate it. One additive I add to my beds is finely ground up eggshells, which are a great source of calcium.

Adding Compost and Mulch

Organic matter is another good soil amendment. There are many ways to acquire it….one of the best ways is compost. Compost sources could be anything like apple or potato peels, melon rinds, things like that we normally throw away but when they start decaying can become a great nutrient source.

Learning to compost well is a skill – you may have to be judicious when you sort your trash but there are no downsides… It’s free or cheap, you do want to be sure to push things like food scraps deeply into the soil (you don’t want to attract nuisance animals, right?)

Mulch is another great component. Mulch is a cover crop that is best applied in the wintertime to stave off potential damage from frost, keep nutrients locked in and prevent water from drainage. Grass clippings, straw, dried leaves and limbs are good examples of organic mulch that can be easily acquired.

Adding Aged Manure

Some of the soil we use in our beds is made from aged manure. Manure has a very heavy abundance of nitrogen, which is an essential nutrient but too high an amount could burn your crops, so that would be something to not use, at least initially. About 6-8 months is needed before it can become usable. Wait and compost it first, allow the odor to dissipate – as it does so it will darken in color.

Well, I think we covered a lot of ground here …(pun intended) Hope this comprehensive guide tells you everything you need to know about how to amend your soil and make its quality the best possible.

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