Everyone has a right to have a productive garden, to grow organic fruit and vegetables, to know what goes into your food and to be able to have real food. Food should be pesticide free, grown naturally just as nature intended it to be.
Soil amendments or soil conditioners are one of the easiest ways to get the ground right to be able to grow the best garden EVER!
For new gardeners, a few questions arise about soil amendments such as how do you know which soil amendment to use? What are soil amendments? Are they even necessary? Read on to find out the answers to these questions and more.
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It’s that time of the year; when emails and catalogues come flying through inboxes, postboxes and mailboxes around the northern hemisphere tantalizing us with the latest seeds, fertilizers and more. It is also the time to be thinking about adding soil amendments to your garden to improve the soil for the growing season ahead.
The snow has melted here in Utah and we’re well within the February thaw. After the loss of Bubba we’ve been making time to appreciate each other whether it was seeing Neil deGrasse Tyson for our anniversary (it was totally awesome and I fell in love with Romanesco Broccoli in a mathematical fractal geek kinda way!), enjoying a good cuppa tea and the best cinnamon rolls recipe, planning the garden redesign together or planting berry canes which arrived.
Since we’re moving to a raised bed garden sooner than originally anticipated (woohoo!), now is a great opportunity to build the native soil and have the best start to the raised beds and everything I’m growing this year!
My family want to get involved with this blog a little more too! So the title for this post was from my ManBear (husband). I thought it was pretty clever but everyone does have a right to have a productive garden to grow real food organically. Why not give soil amendments a try and see if you can get a more productive plot this year?
What are soil amendments?
A soil amendment is any material added to the soil to improve its physical properties. Properties which are improved include water retention, drainage, aeration, structure and increasing the organic content so that the soil is more capable of holding nutrients and moisture.
The goal of improving the soil is to provide a better environment for your plant roots for strong healthy plant growth.
Amending a soil is not the same thing as mulching however, many organic mulches also are used as amendments and may be incorporated into the soil as amendments after they have decomposed.
A mulch is left on top of the soil where the purpose is to reduce evaporation and water runoff, moderate soil temperature, prevent weed growth or to provide curb appeal.
Soil amendments are also known as soil conditioners and just like the hair care ads are telling me that their latest lardy-dah hair conditioner is going to stop traffic, soil conditioners are key in having a show-stopping garden.
How do you know which soil amendment to use?
The simplest way to find out which soil amendment you should use is to test your soil.
The key to a great garden is getting the soil right. As gardeners it is one of our seasonal tasks to assess the soil and replenish missing nutrients and improve fertility so that we can reap what we sow in the months to come.
Test Your Soil
If you are a scientist like me, the prospect of testing the soil is probably quite exciting. There are many soil test kits available for gardeners and I really recommend testing for pH (how acidic or alkaline the soil is) as well as testing for nitrogen, potassium and phosphorus (NPK). They come with instructions and you don’t need a degree in a STEM field to be able to use them.
If you are not comfortable doing your own soil tests, or if you want more information about your soil; you can get more complete soil analysis done. Often your local university extension office or some garden supply stores online offer the service and will come with instructions on how to take a representative soil sample. These in depth soil analysis are ideal if you want to find out more about other trace elements, cation exchange capacity, organic matter and more.
Why you should test
Soil testing may seem like an unnecessary expense but they will pay for themselves in the long run by having highly productive garden areas.
By testing the soil you will know what the strengths and weakness are and armed with this knowledge you can correct weaknesses and imbalances with targeted fertilizing or addition of soil amendments before the growing season starts. Having this knowledge will bolster your growing season and lead to a much more productive plot whether you are square foot gardening in a community garden or farming acres organically.
Types of soil amendments
There are organic and inorganic soil amendments available to gardeners and commercial growers. Organic amendments come from something that was once alive and include wood chips, grass clippings, compost, manure, straw, peat and biochar. Inorganic amendments, on the other hand, are either mined or man-made. Inorganic amendments include sand, vermiculite, rubber mulch and gravel.
When organic amendments are added to the soil, they can also act as fertilizers by providing a mixture of nutrients to plants. Inorganic amendments also add nutrients to the soil but lack the organic humus to improve soil structure.
You should keep a record of your soil test results so that you can track changes over time and look for trends.
Inorganic Soil Amendments
See below for typical inorganic soil amendments and their uses.
Azomite acts as a re-mineralizer for soil which comes from ground deposits. It contains trace minerals magnesium and calcium.
Sometimes called Glacial rock dust and is ground up glacial rocks providing readily available trace minerals, calcium and magnesium. It is also a good source of iron and potassium and can help reducing the effects of soil depletion.
Provides slow release of potassium and trace-minerals. Greensand is glauconite, an iron potassium phyllosilicate (for the geologists) which can improve moisture retention and loosens hard, compacted soil.
Humic acid and humates are usually combined in products. They come from ancient remains of living matter and are believed to increase nutrient uptake by plants. These products come from Leonardite shale. There is some research which suggests that these materials with chlorinated drinking water form toxic compounds. Use non-chlorinated water when watering if you plan on using this in your garden.
Epsom Salt is magnesium sulfate crystals which can provide a nice soothing bath and you can add your bathwater to the garden for a magnesium boost for the soil and your plants!
Dolomite or Lime
Lime and dolomite are used to increase or raise the pH of the soil making it more alkaline. Dolomite is used to raise low pH soils where magnesium and calcium levels are low. If your soil has high magnesium and calcium, limestone or oyster shell lime are a better choice.
Helps to break up clay soil. Gypsum contains calcium and sulfur and is also used in brewing to alter the composition of water for many beers like a dry Irish stout although not fertilizer grade gypsum.
Pumice is a porous volcanic rock that aids soil aeration. It also helps to opens up clay soils.
Like vermiculite, perlite is often used in hydroponic and aquaponic growing and is also added into potting mixes or seed starting blends. Perlite reduces compaction and improves drainage.
Organic Soil Amendments
I mostly use these in the garden because they are more readily available and my sandy soil needs more organic matter to bind or aggregate the soil particles.
Easily available for most gardeners from your own garden by making it, local landfill or dump and buying compost online. Compost provides humus, organic matter and beneficial microorganisms as well as nutrients to the soil.
Nothing beats good old fashioned muck as my Granny says. Manure needs time to mature, like a great whiskey or wine (yup I went there). If you use it fresh the high nitrogen content from the ammonia will cause your plants to “burn”.
Worm castings are a great all round soil amendment. They add humus, enzymes and microorganisms to the soil for fertilizing and improving soil structure.
Made by heating dry wood to high temperatures with low oxygen. Biochar is like charcoal with a vast porous surface area which allows ot to hold soil microbes, nutrients and water.
Humus provides organic matter to improve soil texture and structure. Some humus blends contain beneficial microorganisms that help increase availability of nutrients in the soil.
Mycorrhizal fungi and soil microbe inoculants are an easy way to boost numbers of beneficial microorganisms to the garden. These microbes work with plant root systems to allow greater uptake of nutrients which leads to stronger, healthier plants. These come as powders for compost tea, inoculants and boosters. I use Organic Plant Magic currently and I’m running some trials with it in the garden to find out how to get maximum benefit.
Application Rate of Soil Conditioners
Most commercial products provide guidelines on applying soil conditioners and amendments. Some soil amendments may be high in salts and the amount to be added to the soil is
limited due to salt burn of roots. This causes death of plants because they cannot grow without good root structure.
Typically soil amendments are added between 5 and 50 lbs per 1000 sq. ft. of soil. Some common application rates are:
1 cu. ft. per 200 sq. ft.
10 lbs per 100 sq. ft.
5-20 lbs per 1000 sq. ft.
50-150 lbs. per 1,000 sq. ft.
Manures must be well rotted or composted before use. Fresh manures burn plants because they are high in ammonia or ammonium salts. Fresh manures may be applied to the soil in autumn for spring planting in the same area.
Do you have favorite soil conditioners and soil amendments you like to use in your garden? Please share them in the comments or at the Misfit Gardening Community Forum, we would love to hear your ideas and tips.
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