Wednesday, October 30, 2013

Sifting Garden Soil

First if all, let it be known that I don't sift my garden soil except for the carrot bed. I have my reasons. Read on.

This week I read an article instructing new gardeners how to start a garden bed. One of the steps included sifting the soil through a 1/2 piece of hardware cloth. I not only find that not to be necessary, I find it to be detrimental. By sifting, one removes all small stones and cinder larger than 1/2 inch, chunks of organic material, half rotted leaves and grasses, decaying roots and rootlets. All the things being removed are important soil components, in my opinion. 
Rocks to the left. Organic debris on the right. I leave it all in place. 

Small rocks & cinder:
          I keep anything smaller than a hen's egg. Bigger pieces interfere with the rototiller. But rocks and cinder help with drainage, help maintain soil structure, and are a source of minerals for plants, microbes, and other soil denizens. It makes no sense to me to remove small rocks via sifting then later add rock dust for minerals and cinders for drainage. Hey, it was already there before you removed it! The soils of England are a prime example of the adverse effects of rock removal. For decades small children were rewarded for removing stones from the fields. Those soils now suffer the effects ....compacting, clumping, draining poorly, lacking mineral fertility. 

Organic material (rootlets, leaves, twigs, etc):
         Sifting the organic material out, then turning around and adding compost sounds like a waste of good time and effort. Why not just leave the decomposing material right there in the soil in the first place? The microbes that specialize in breaking that stuff down are already in place and doing their job. Besides, the chunky stuff helps retain moisture while at the same time promoting drainage. 

The only place where I sift soil is the bed dedicated to carrots. Reason? Rocks cause the roots to split and grow weird. I find that this sifted soil is more difficult to maintain. It drains poorly. It tends to become hydrophobic if it dries out. Worms don't like it. It compacts readily. 

My suggestion -----  skip the sifting. Just pick out the big pieces if they get in the way. 

1 comment:

  1. I used to sift a lot, when I dug out garden beds in the Mojave desert, but the amount of organic matter was the key there, with pea gravel and sand serving to prevent compaction. Drainage was excellent. In more clay-containing soil in old orchard that became suburbs in SoCal, the trick for straight carrots was to use a flat spade to cut a slit that was widened by rocking the blade back and forth, then dribbling in various blends of bone meal, greensand, and sharp sand to fill it, with a ribbon of loamy soil to get the little carrot seeds off to a good start. Easy to pull nice straight carrots there, too. I am just starting my garden beds here in coastal Oregon, using the lasagna method with cardboard, da kine, to gradually decompose as they are patiently composed, with the rainy days just starting tonight. Lots of grass clippings, dandelions, and prunings from the old fruit trees will cover successive layers of cardboard. I peeked under one corner and saw an earthworm already mining vertically! Maybe the only sifting I'll do is for making seed starting mix.