A month ago I wrote about slugs
because we had been having rain for a week. As I look out at a garden that looks like a
rice paddy I realize I can't do that column again. How about leaching?
When there is this much rain all that water has to go
somewhere. First it saturates the plants. Just as it remains dry under trees during a
light shower, the smaller plants have to become saturated before rain reaches the ground.
Then the ground gets saturated. Then the water in and on the surface of the ground starts
to move. The water in the ground moves deeper replenishing groundwater supplies. The water
on the surface starts to run-off, pondding in low areas and swolling streams and rivers.
Where the water ponds, as in my garden, it will eventually seep into the soil as the water
below seeps deeper.
The water picks up anything that is
soluble in the soil and even carries small particles of soil. Particles of soil moving on
the surface are seen as erosion. If there is erosion in your garden, there are several
actions you should take. Always plant across even a gentle slope, never run rows up and
down hill. Mulch is a wonderful means of controlling erosion. If the slope is greater than
gentle, you should consider terracing. Make your garden into a series of level steps
running across the slope.
The water that seeps into the soil is
also a problem, especially in the spring and early summer. Plants need water soluble
nutrients. Conventional commercial fertilizers are all water soluble. Rains like we have
been having literally wash the fertilizer out of the soil. This is called leaching.
Organic or natural fertilizers will
also lose water soluble nutrients but the loss won't be as great. If you have compared
bagged natural fertilizer to chemical fertilizer, you have seen that the
nitrogen-phosphate-potassium (N-P-K) on the natural fertilizer is generally much lower
than on the chemical fertilizer. It might be 5-3-4 for example versus 5-10-10 or higher
for chemical. This is the percentage of soluble nutrient in the bag.
The rest of the stuff in the bag in
natural fertilizer is organic material that is food for soil microorganisms. In the
chemical bag it is inert ingredients. The organic material and the microorganisms do not
leach out of the soil nor are they very likely to be carried away by runoff though some
organic matter may float away. The microorganisms keep right on breaking down organic
matter into soluble nutrients. That is the beauty of organic fertilizers. The advocates of
chemical fertilizers talk about how much more potent their fertilizer is and how less has
to be spread. They will also tell you about side dressingadding fertilizer during
the growing season. Organic fertilizers can be added during the growing season, too, but
if you have a good organic soil going, I can't see any reason to do it.
There is one other concern over the
leaching of garden chemicals (this includes N-P-K in a natural garden). Where do the
chemicals go? Into the ground water, of course. This is not likely to be a detectable
problem in non-farm areas though the amount of chemicals spread on lawns is horrendous and
is certainly a potential problem. Children have died from nitrates from farm fertilizers
and from poor stockpiling of manure which showed up in the farmer's well water. The
chemicals on lawns probably do not become a detected groundwater problem because in areas
where there are a lot of these chemicals the residents are on municipal water. I shudder
to think of the damage lawn chemicals are doing as these torrential rains sweep them into
our lakes, ponds, streams, rivers and estuaries. This is the time of year when the lawns
have the most of these chemicals on the surface and available to be carried off.
ŠJune 14, 1998
is a husband and father. He authored a book, Gardening For
Independence and was named Environmentalist of the Year by Down East Magazine
in 1987. You can eat his organic produce at
his son's southern Maine
restaurant. His address is 802 Bald Hill Road, Wells, ME 04090.
Mort retains all rights to his
columns. Anyone interested in using them can get the rights at a very reasonable rate.