Monday, 23 May 2011

How Liming With Dolomite Lime Can Damage Your Garden

Many gardeners are now using dolomite lime in their garden, thanks to the successful marketing strategy of the people behind the dolomite industry. They actually do a pretty good job in selling dolomite lime because more and more people are now persuaded to apply this product in their gardens.

They're right when they say that fertilizing is best done when aerating a lawn, but for the most part, dolomite is the wrong fertilizer.

A search through both conventional and organic gardening websites and books reveals that most garden experts happily pass on this information.

Occasionally, using dolomite lime is warranted, but the truth is, it often makes things worse, sometimes just a little, and sometimes a lot. Let's look at why...

What Is Dolomite Lime?

Dolomitic lime is a rock. It can be quite pretty. It is calcium magnesium carbonate, CaMg(CO3)2. It has about 50% calcium carbonate and 40% magnesium carbonate, giving approximately 22% calcium and at least 11% magnesium.

This can be bought for your garden in granulated form - can be very fine or course - or made into a prill.

Dolomite lime fertilizer is not totally bad. It is used in some organic gardens, and the way it is used can have mild or severe results on the garden.

Why Are We Told To Use Dolomite Lime?

I already tackled this topic before when I talked about the pH level of your soil - where constant raining can wash away other minerals, which can result in your soil having a higher acidity level.

To oppose and mitigate these effects, dolomite limestone is usually used in the garden. However, this doesn't mean that using it is totally safe.

Why Are Minerals Leaching From Your Soil?

Minerals can be drained away from the soil - thoroughly or partially, because of rain, but there are still other explanations.

Soils that are high in sand and silt, and low in organic matter, don't hold onto minerals as well as a clay soil, or a soil high in organic matter.

Chemical fertilizers cause soil acidity, too, so if you're using them, that is probably part of your problem, as well. Dolomite lime fertilizer won't help. Let's look at why dolomite is probably not what you want.

Here's The Important Part

The main point I want to make is that even if minerals are leaching from your soil, it doesn't make sense to blindly go back adding just two of them (the calcium and magnesium in dolomite lime) without knowing you need them. You might already have enough or too much of one or both of them. We need to think a little more than that when organic gardening.

Your soil needs a calcium to magnesium of somewhere between 7:1 (sandier soils) and 10:1 (clayier soils). Outside of this range, your soil will often have water problems, your plants will often have health problems and insect and disease problems, and you will have weed problems.

To shift the calcium to magnesium ratio to a better level, adding a particular type of mineral to your soil would be the number one priority. If you want to grow naturally healthy plants in your garden, you will need to balance-out the calcium to magnesium ratio of your soil.

The percentage ratio of dolomite lime is 2:1 calcium to magnesium. This is the main issue with this fertilizer. It contains too much magnesium, and although magnesium is important, too much of this mineral can lead to major issues like soil compaction and other problems, including weeds.

Like I said, adding dolomite lime every year in your garden will probably create more problems.

When To Use Dolomite Lime?

You should only use dolomite lime when you have a soil test showing a huge deficiency of magnesium in your soil.

In other words, you can make use of calcitic lime rather than dolomite because it has about a 6:1 calcium to magnesium ratio, which has 30% to 40% higher calcium content compared to dolomite.

Normally, I use calcitic lime in my garden, but then again, I usually have a soil test first before adding any fertilizers to my soil.

Questions? Let me know below.

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