07 May 2012

Soil Amendments for Beginners

Welcome to Garden Month!  Let's talk about soil amendments.  If you're taking the time to garden so that you can feed yourself healthy things, then it stands to reason that you'd also be willing to feed your plants healthy things so that they produce even MORE healthy food! 
Over farming and mono-farming has left the soil depleted.  Think of it this way:  if you had a whole city of people just like you, then when you all went grocery shopping, everyone would be shopping for the exact same foods.  The grocery store would quickly run out of some things, and other things would be overstocked.  It is the same with soil.  If you plant corn for acres and acres, that corn is going to eat up all of the nitrogen in the soil.  This is why farmers need to add chemical fertilizers to the soil.  This isn't sustainable or healthy.  A healthy garden would have diversity, so that some plants would add nitrogen to the soil and other plants would eat it up.

The minerals that are key to the health of the plants and our health are missing in the soil.  So we need to add those back so that the vegetables we grow have all the nutrients that we need.  This is an important reason to grow your own food.  Vegetables in the grocery store today have much lower mineral content than they used to.

Feeding Your Outdoor Garden
So what do you need to add to your soil?  Well, that depends on what your soil is missing.  Here in Michigan, you can send in a soil sample to the MSU Extension office and get a full soil report for $22  (not in Michigan?  You can probably find the same thing at a state university).  In the meantime, here are the things that your soil might want:
  • Compost - recycled organic matter from food preparation, yard trimming, etc.  This link has a very helpful table of things that you can compost, and what they add to the soil.  Composting could very easily take up a whole blog post by itself, but I'm not that intense about composting yet.  Maybe next year.
  • Kelp meal (seaweed!  It's good for everything - feed it to your plants and your animals!) - kelp adds potassium, as well as a plethora of other trace minerals and micronutrients.  It also helps soil retain water.
  • Azomite - adds a lot of trace minerals to the soil. These trace minerals boost plant immunity and resistance to adverse conditions and aid flowering and fruiting.
  • Biochar - the "clinkers" left over in your ash - this leftover organic matter is extremely porous, so it holds moisture and minerals that plants love.  Follow the link for an in-depth lesson on how wonderful biochar is for gardens. 
  • Peat moss - holds moisture, keeps the soil loose, keeps nutrients and minerals from leaching out of the soil.
  • Leaf mold - the easiest thing on this list.  Maybe you have a park nearby that rakes up all their leaves every fall and drops them all in the same place.  At the bottom of that years-old pile. you'll find the mucky, decomposed leaf mold.  Or you can make your own for a little extra effort.  It does many of the same things as peat moss - holds moisture, keeps the soil loose, and it also adds calcium and magnesium.  It is very good for clay soil.
  • Perlite - also good for clay soil, it helps break up the compacted soil and provides better drainage.
  • Greensand - it has high concentrations of minerals (like potassium) and releases them slowly; it is a natural fertilizer.  It also helps the soil hold water.
  • Feather meal - extremely rich in nitrogen.  It provides both a quick boost and a slow release.
  • Rock phosphate - adds phosphate to the soil.  Bonemeal is a good substitute if you can't find rock phosphate.
  • Lime - add this to soil to lower the acidity (aka raise the pH level)
Image sources: 1 2 3 4 5 6

That's a lot of information!  So if you're feeling overwhelmed, just remember this:  The best soil amendments increase water- and nutrient-holding capacity and improve aeration and water infiltration.  

These soil amendments aren't sustainable either.  You shouldn't have to add a ton of stuff to the soil every year in order to grow things.  The idea here is that you remineralize your soil the first year, and next year it won't need quite so much amending.  Eventually, you can start dedicating part of your garden to growing your own compost (like John Jeavons outlines in his book, How to Grow More Vegetables Than You Ever Thought Possible, which is somewhat summarized in this article).  Also you can start practicing companion planting and crop rotation.

So the big question now is how to apply these soil amendments.  I'll go over that in my next post, which will be about double digging.  I also have an upcoming post about companion planting, which will include the layout of my garden this year!

Feeding Your Container Garden
Craig Schaaf's soil mix is great for starting seedlings indoors - he uses them to make soil blocks, which he later transplants into the ground.  Recipe makes 80 qts, or is available for purchase pre-mixed at Craig's farm.
  • 30 qts peat moss
  • 25 qts compost
  • 15 qts leaf mold
  • 10 qts perlite
  • 1 c. greensand
  • 1 c. sea life kelp
  • 1 c. feather meal
  • .5 c. Tennessee brown rock phosphate
  • .5 c. colloidal rock phosphate
  • .5 c. lime
Not the kind of recipe you normally see on this blog! You don't have to dive right into all these things, but if you're a new gardener, the important takeaway here is that in order to grow the best plants and vegetables, you need to start with a healthy, living soil.

Happy gardening :)

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