I often wonder why I spend most of spring pulling weeds. I became a defacto gardener after I bought my house seven years ago-and soon realized that my small square footage house had a complex yard with multiple climate microzones and a consuming outdoor maintenance schedule during all four seasons.

I decided early on to never use chemicals in my yard. Being a former student of Agroecology, this became my mantra. I have to admit my copy of “Teaming with Microbes –  The Organic Gardener’s Guide to the Soil Food Web” by Lowenfels & Lewis has sat unread on my bookshelf for years. I picked it up this winter and am conquering the science-y chapters one at a time, slowly comprehending the mission of understanding how microbes, bacteria and fungi all interact like one big happy family to keep my little microcosm of a yard and garden in harmony sans industrial chemicals.

I know, I know, I’m kind of a worm and insect Guru.  Everytime I scoop up some dirt, worms and larvae and insects crawl out of each and every clod…I swear they look up at me and say, “Hey thanks Lady for not dumping a bunch of junk in our house”…but that might be the wine talking. I started wondering why do I have so many dandelions          and gobs of crabgrass overtaking my yard now? Turns out-my soil is lacking in Calcium after a quick Google search. Thanks internet. Here’s the skinny on Calcium soil amendments for your yard and some quick DIY pH tests you can try without having to purchase a soil pH test kit.  

Dried crushed egg shells – save all those shells. Dry out, pulse to a powder in your food processor. Lasts 3-12 months depending on quantity used and distribution percentage.

Ground oyster shells – available at any garden center – Lasts 1-2 years. Slow release.

Gypsum is 23% calcium and 17% sulfur, which means that it can provide a source of calcium without raising pH levels. Improves drainage by aerating the soil, neutralizes plant toxins, and removes sodium from the soil. The sulfur reacts with water and forms a weak sulfuric acid that frees up calcium.

Calcitic Lime vs Dolomite Lime – very different products. Both hail from ground limestone but you must discover your soil pH level first to determine which product to use. If soil pH is below 7 (acidic) you should raise the pH with Lime. I f soil pH is too high (above 7, alkaline) you can lower the pH with compost, worm castings, or Sulphur. Calcitic lime and dolomite lime are both made from pulverized limestone and both are effective at raising the pH in acidic soils. They have a different influence on soil, however.  Dolomite lime contains large amounts of magnesium along with calcium carbonate while calcitic lime only contains calcium carbonate. Magnesium is an important mineral for plant health. And if soil needs magnesium, wouldn’t it be best to just use dolomite lime all the time, just in case? Not if too much magnesium can also be a problem.

You’ll want to determine if your soil is lacking in minerals first. The soil type can usually point you in the right direction. Clay and clay loam soil tends to retain magnesium well because it drains poorly. Loam soil also retains magnesium well, but under certain conditions it can become magnesium depleted. Finally, sandy soil is much more prone to mineral loss because drainage can leach the soil.

  • dolomite lime (magnesium carbonate)

Dolomite lime contains large amounts of Magnesium. Magnesium deficient plants are often yellower, have shorter root systems, and produce noticeably lower yields than plants grown in healthy soil. Excess magnesium can cause your soil to become overly compact, deterring plant growth while also making the soil more difficult to water efficiently. It may also cause unchecked weed growth.

Magnesium deficiency is likely in quick draining sandy soils, while clay and clay loam soils rarely suffer from magnesium issues.  Dolomite can make soil compaction worse.

An incorrect application of dolomite lime (and magnesium) can be tough on your garden and soil, so for most purposes, plain calcitic lime is usually adequate. It works quickly to restore soil pH and doesn’t increase the risk of too much added magnesium.

  • calcitic limeThe main “ingredient” in calcitic lime is calcium carbonate.  It counteracts the acidification of soil. In addition to neutralizing pH, lime also encourages the growth of micro-organisms that contribute to plant health. With the combination of helpful micro-organisms and pH balanced soil, plants and crops will thrive.Calcitic lime works effectively, even with one treatment. If you garden every year, calcitic lime will likely be the only treatment you’ll need.

    Calcitic lime also works more quickly than dolomite lime: Calcium carbonate is better at balancing pHs than magnesium carbonate, and calcitic lime contains much higher levels of calcium carbonate than dolomite lime. Calcium is a component of plant cell walls, and it’s needed for enzyme formation and nitrate uptake. It helps neutralize excessively acidic soils, which is especially important when you’re growing green, leafy vegetables like lettuce and spinach, or cruciferous vegetables like cabbage, broccoli, cauliflower, and kale.

    Calcitic Lime’s Limitations

    Typical calcitic lime treatments require some patience.Water is required for the chemical process to begin and the calcitic lime must be worked into the soil a little to help activate it. However, calcitic lime won’t replace depleted magnesium. If your soil is magnesium deficient, calcitic lime treatments won’t improve plant health.



How to test soil pH without a test kit:

  • Vinegar/Baking soda method:

Collect 1 cup of soil from different parts of your garden and put 2 spoonfuls into separate containers. Add 1/2 cup of vinegar to the soil. If it fizzes, you have alkaline soil, with a pH between 7 and 8.  If it doesn’t fizz after doing the vinegar test, then add distilled water to the other container until 2 teaspoons of soil are muddy. Add 1/2 cup baking soda. If it fizzes you have acidic soil, most likely with a pH between 5 and 6.

If your soil doesn’t react at all it is neutral with a pH of around 7 – the ideal range.

  • Cabbage water test: 

Measure 2 cups of distilled water into a saucepan. Cut up and add 1 cup of red cabbage. Simmer for 5 minutes. Remove from heat and allow it to sit for up to 30 minutes.

Strain off the liquid – which will be purple/blue. This will have a neutral pH of 7.

Add 2 teaspoons of garden soil to a jar and a few inches of cabbage water. Stir and wait for 30 minutes. Check the color. If it turns pink, your soil is acidic.  If it is blue/green, your soil is alkaline.

Good luck and don’t forget to leave some dandelion blooms for the Bees the first few weeks of spring! dandelion-weeds-indicator-plants


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