Is Lime Sustainable Fertilizer?

Mining limestone is big business, but does it give us a sustainable fertilizer?

The world's biggest limestone quarry is right near the top of the state of Michigan on Lake Huron. It's 7000 acres, roughly half the size of Manhattan.

I'm not sure how much of the material from this particular quarry goes toward agriculture, but lime is one of the most important fertilizers in organic gardening.

There are different kinds, the best for gardening and farming usually being calcitic lime, which supplies mostly calcium and not too much magnesium.

The Importance Of Calcium

Calcium is critical in order for so many good things to happen in the soil and plants. Interestingly, it's the most needed element by weight and volume for plants, and without sufficient calcium, nothing works.

While nitrogen and potassium get a lot of attention, more and more focus is being put on calcium, particularly in organic gardening. Calcium helps plant cells communicate with each other by physically moving between cell membranes.

Not only is it integral in the basic structure of plants, with a deficiency often showing up as thick, woody stems, it’s largely responsible for the availability of nutrients in plants and has a strong influence on microbial activity.

In the book Mainline Farming For Century 21, Dan Skow says "calcium is essential for its energy creation potential in the soil to release the other elements that cause a plant to grow."

Why Considering Your Inputs Is Important

Why I'm discussing mining limestone today is to bring up the point that when we mine and use this stuff, it's gone. When you get into organic gardening, you start to think more about sustainable fertilizer choices and even the sustainability of your actions outside the garden. This is important stuff.

That huge quarry is going to run out of lime in 100 or so years. In the case of calcium, we still have plenty on the planet, but we're actually getting close to reaching "peak phosphorus" (like peak oil but for phosphorus). That's a huge issue.

Are you one of those people who think we should be gardening without external inputs? Without fertilizers and imported compost?

Because I am. And yet, I don't know how to do it. I can do quite well with just compost and microbial inoculants such as compost tea and effective microorganisms - I can get maybe 90% of the way there. I can get a nice-looking garden.

But if I want to get my vegetable garden to a state of health where most pests go away and the food I grow gives me the nutrients I need to be healthy, it's much easier if I have a balanced soil. Unless I've been lucky enough to stumble upon that, it requires a bit of tweaking early on in my garden's life.

Why I Often Need Some Organic Fertilizers

Of course, in a well-balanced ecosystem, external inputs aren’t necessary. Nature does most of the work and there is always some plant that will happily grow. But I'm growing many foods that simply wouldn't grow in my soil if they had the choice.

It's not that I'm growing plants that are entirely unsuitable for my climate. It's just that in nature, plants only flourish in soil conditions that are right for them. Take weeds - they're just plants that are adapted to your soil conditions and show up first.

So for the most part, I can't just throw some veggie seeds onto my soil and expect them to be happy there.

Much of our soil has been tremendously altered in the past by deforestation, farming methods, tilling, chemical use and on and on to the point where it could use a little help from us. We don’t want to wait 10 or 100 years to be able to grow optimally healthy food.

So this is why we may concede to ship some lime halfway across the country to get more calcium into our soil. Being environmentally conscience, we don’t want to ship this lime and we may not want to be mining limestone in the first place.

This is a complex topic that merits debate, but I believe until we learn to tap into other energies to balance our soil nutrients, we need to do it. We need healthy plants and we need healthy food right now.

Sustainable Fertilizer - What Does This Mean For You?

If you're wondering where to focus most of your attention for soil building, not to worry, it's still on composting and mulching and plain old proper watering. Even if you have a tiny backyard, you can get a small compost bin going, and all you need is a little of the good stuff to provide you with the nutrients and microbes your garden needs.

It's interesting, 95% of what your soil and plants need is carbon, oxygen and water. Organic matter helps with all of those. But like I said in my photosynthesis simple explanation, 5% of what they need is specific nutrients.

A few of those nutrients need to be in specific ratios in the soil. That's why you may need to bring in a few external inputs if you are serious about producing the healthiest plants, especially food. That's when you take a soil test and add the deficient minerals. It may only be 20 pounds of organic fertilizer per 1000 square feet of garden.

Even in permaculture, which is a design approach that's very concerned with sustainability, it is generally agreed that bringing in some inputs early on in the process to get things productive much more quickly is important.

So while I keep my inputs to a minimum, I do use them in the early years of a new garden, especially a vegetable garden.

What are your thoughts on this? Do you try to use sustainable fertilizer sources? Or do you try to get all of your nutrition from materials on your property like compost?