Tuesday, May 10, 2011

From clay to soil.

Most of the soil in Milwaukee is clay. While trees and shrubs do well in clay soil, smaller plants (like bulbs, vegetables, flowers, perennials) will not do so well. Lets look pros and cons of clay soil, and what you can do to fix the soil.

The Bad News:
  • Clay is dense and compacts easily, preventing roots to grow well.  Bad for root crops and starting from seed. This is also why it clomps together and sticks to your shoes. Don't work the soil when it is wet, it just compacts more.
  • When clay drys out, the soil crusts over and cracks. This rock hard crust makes it hard for seeds start growing and find sunlight. The crust also more run off  from rain.
  • This soil is slow to warm in the spring. Bad for germinating seeds and plant growth.
  • Slow the drain water. Soil that is constantly wet, will rot the plant's roots.
  • Damaging to plants over the winter (Winter/Frost Heaving)
The Good News:
  • The soil retains water, meaning less watering is needed. This is a great for raise garden beds, where other soils dry out too fast.
  • Usually, clay is more richer in nutrient then other soils types
  • Good for making seed balls

What can you do?
Amend the soil by mixing in organic material.
Mixing things like leaves, grass clippings, and compost is great for amending any soil. I have been doing this every fall for 2 years with great results. I mix in leaves using a shovel and over the winter the worms do their thing, making the soil better. This is not a instant change from clay to garden soil. From my progress, I am guessing after the 4th year I should have that 'garden soil' you see sold in the stores. However my tomato plants did great even after the 1st year.
I know mixing manually is tough. You could use a tiller, but using a shovel to mix in leaves is better for the soil (about.com). I use a ratio of 60% soil to 40% leaves, because the leaves compact down when mixed. If you have extra leaves, maybe you should save some for your composting needs next year. Shoveling is a lot of work and takes me about 2-3 days to do a 8ft x 20ft garden bed, but it is a great way to burn off that thanksgiving dinner. Here are some picture of what I have done: clay soil

Build on top of the soil. 
You could just build raise garden bed on top of the soil and fill it with garden soil. Remember just like container planting, you will need to replace the soil each year. I'll warn you it can get expensive depending on your garden size. This is what Mel Bartholomew recommends in his book 'Square foot gardening'.  Mel cites that this is less work, better soil, and usually better results. I think it is good plan if you are doing a small 4ft x 4ft garden and might be moving soon.

Plant clay friendly plants.
If you can't beat them... actually plants that do well in clay soil, slowly start repairing the soil. Beans, Pees, Potatoes, Cabbages, Brussels, Kale, and Legumes are some good plants (plants for clay soil). Cover crops (clover, rye, or oats) plated in September and then chopped down in May also help repair the soil (improving clay soils). I haven't tried cover crops but it sounds easy enough.

What ever you choose, let me know. Clay soil is a challenge. It is always helpful to learn from others.