Saturday, November 3, 2012

To Till or Not to Till

I grew up in Iowa, and I remember the 1980's drought in little mental movie clips.  I remember a newscaster on TV standing on very badly cracked soil, talking about all the farmers who could lose their crops.  I remember my grandparents watching heat lightning in the distance and being terribly upset that there was no rain to accompany it.  I also remember driving down the interstate and watching waves of soil blowing off the fields in the wind, because the plowed fields were just too dry to hold the soil down.  The solution to this last problem - according to the state - was for farmers to switch to no-till farming. 

This winter, while working on the Great Cardboard Project, I saw a similar thing happening in my garden.  It reminded me that it's always bugged me that gardeners are encouraged to till their soil, the exact thing farmers are not supposed to do.

What are the advantages of tilling?
  1. weed control - conventional no-till farmers often use herbicides to clear the weeds from their fields before planting, which home gardeners (and organic producers!) are often loath to do
  2. insect control - many insects live at least one stage of their life cycles underground, and can be disrupted by tilling during that period
  3. warms the soil - tilling brings darker soil up from below and displaces organic material from the soil surface, allowing the soil to absorb more energy from the sun
  4. dries the soil - tilling helps dry the soil in spring more quickly
  5. incorporates organic matter into the soil
For all those advantages, though, my brother-in-law says his yields are higher with no-till methods.

What are the disadvantages of tilling?
  1. organic material is consumed more quickly
  2. more topsoil is lost to wind and rain
  3. beneficial soil organisms are disrupted/destroyed
  4. takes a lot of time and energy 
  5. raises buried weed seeds to the soil surface
  6. nitrogen in the soil is temporarily tied up
This year I have been turning the soil less and less, focusing more and more on mulching and hand-weeding and reminding myself that if I consistently keep the soil covered with organic material, the soil organisms will move that material down into the soil.  This is the sort of time-intensive manual labor that the plow and tiller were invented to replace, and I have yet to conceive of a good way to scale it up to larger areas.

As I've mentioned in other posts, I'm also trying to keep the beds planted as much as possible, and I'm working on a comprehensive planting/harvesting plan for next year to make that happen.  Keeping the soil covered with mulch and/or crops goes a long way towards suppressing weeds.

A few remaining summer crops, surrounded by bare soil being colonized by weeds

No comments:

Post a Comment