|Back to Back Issues Page|
Lorraine's Garden, Issue #006 -- Garden Planning Tips
January 08, 2014
January 2014 Issue 6
In this issue:
Garden Planning TipsI just love it when all my favorite, mouth-watering seed catalogs start coming in the mail. The garden is still a perfect, weed-free, overflowing dream in my head, and I conveniently forget the heat and the weeds. (Or if I do bring them to mind, it is with a certain romantic nostalgia that only winter can induce.)
Even though the first ripe tomato is probably 7 months away, I start drooling with anticipation. The time for planning the garden has arrived!
Here are some planning tips to keep in mind as you leaf through the catalogs:
Soil Science Lesson: Cation Exchange Capacity: Part 2So after last month’s homily on what cation exchange capacity is, why is it so important?
CEC is an indication of how much cation plant nutrition your soil can hold (similar to having cubbyholes in a pantry). A loose soil like sand has very few of these “cubbyholes” and is not be able to hold much plant nutrition, whereas a loam soil which contains a little clay may be able to hold a lot. The more your soil can hold (the higher the CEC), the more resistant it is to losing plant nutrition by it washing away, or “leaching”, and the more fertile it can be.
Sandy soils may have a CEC of only 3-5, silty loams a CEC of 10-25, clay loams a CEC of 30-40, and organic "muck" soils a CEC of 50-100.
If you have low CEC soil (3-5), you can increase the CEC by adding lots of completely-broken down, well-balanced compost, or you can boost it even more by taking a tiny bit of clay dug up from the subsoil (or taken from an exposed road cut), pulverizing it and mixing in with the compost you add.
With a low CEC soil you will also need to fertilize more often, because the fertilizer will wash away more quickly. If your CEC is above 10, annual fertilization should be sufficient.
Base Saturation: Calcium, Magnesium and Their Friends
Roughly speaking, the total cation plant nutrition a soil actually does hold is referred to as “base saturation”, which is given on a soil test report as relative percentages of each of the cation nutrients. What does that mean?
Whether your soil holds a lot or a little, whatever that total CEC amount is can be seen as “100%”. On a soil test, the relative percentages of the various cation plant nutrients - namely calcium, magnesium, potassium, sodium (and a few others) - will add up to that 100% total.
Now from a plant’s perspective, the tastiest soils seem to have a ratio of about 68% calcium to 12% magnesium, or what some have called an “ideal soil”. For complicated reasons, when the calcium/magnesium ratio is right, the pH will be right, the soil microorganisms will be happy, and plants will be happy, provided they have enough of all the other macro and micro nutrients.
Most of us tend to think only of Nitrogen, Phosphorus and Potassium, or N-P-K when we think of fertilizer. They are the biggies, but for optimal soil health, we also need to consider the presence of calcium and magnesium in the right ratio.
I encourage everyone to have their soil tested and optimize their soil minerals, so they can grow the most nutrient-dense food possible. Healthy, balanced soil also means fewer bugs!
Happy garden planning!
|Back to Back Issues Page|