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12 April, 2010

Preparing the Soil for a Garden

Doing a quick make-over of the soil - students dig in some compost into the top few inches of a garden before they begin to plant.  Rushed for time, we didn't get to cover soil preparation as thoroughly as it needed to be done.

First off, there are many competing theories about what comprises a good start on a garden. Some folks do double digging and some folks do no digging and a whole host of different philosophies exist in between. I would urge everyone to try each one and settle on the one that speaks to your ability and needs.

I have a bad back. The area I garden (at The Learning Garden) has not been dug for over 9 years. I don't do it because I'd be prone the next week. And I have come to feel that digging is not only unnecessary, it is harmful to the soil in the long term. But let's explore some of the ways other folks see this idea of digging.

John Jeavons has a non-profit up in Willits, California called Ecology Action. They sell seeds (that is a company called “Bountiful Gardens”) is a proponent of 'double-digging.' This is a method essentially brought to this country by an eccentric Englishman, Alan Chadwick, who taught a long time on the east coast, but the last years of his teaching life were spent in San Francisco and Santa Cruz where his mark is still indelible on the gardening communities of both cities. Smith and Hawken, the tool company that recently folded, was founded to supply Chadwick and crew with the English spades and forks Chadwick demanded.

Double-digging is spading your garden to the depth of two spade blades. One first digs into the soil with a spade and removes that soil (saving it to use later), then plunges a spading fork into the bottom of the hole just dug several times to loosen the soil beneath. The soil from the second row goes into the vacated first row and the soil from the third row is dropped into the second row and so on until, at the end, the soil from the first row is wheeled around in a wheelbarrow to fill the final row.

Soil treated like this, then has a tremendous amount of air in it and all that air can easily be replaced by plant roots and water. Plants grown in such soil are usually quite happy – although some fertilizer will usually need to be added because all that soil disturbance is damaging to the soil biota. But that's my theory. Jeavons is a published author and thousands of folks follow his teachings. He has proven that it is possible to grow an entire family's calories and nutrition on one hillside and I haven't.

There is the single dig method, which has been practiced by gardeners for hundreds of years. Go into the garden only turn over as much soil as the one spade or shovel blade reaches. This is about half as difficult as the double-dig method for obvious reasons. It also produces results.

The no-dig method is to simply clear the soil of other plants and begin to plant. Sometimes, when the underground stolons of grass are present, some digging is required to get those nasty roots out. But that doesn't count as 'digging' being classed as 'weeding.' I will put up another article on something called sheet-mulching that will get rid of most of the grass without digging, but it requires some time (9 weeks or so).

One can add lots of compost or organic matter in any of the above systems. Compost, by the way, is one type of 'organic matter.' Organic matter is anything that used to be a living thing. In our gardens, we usually take it to mean living plant material, excluding most animal feces and body parts. But the skin of an avocado or a banana, orange peels, coffee grounds, overcooked spaghetti, apples gone south, carrot tops and such – we even allow for egg-shells, hair and fur. Grass clippings, weeds and old broccoli plants can be added to the list – although, when one talks of adding organic matter to a garden bed, one is usually talking about something that is small and will break-down somewhat quickly. Rice hulls, hops and grain from beer brewing – the Garden had a woman near by that was crushing coconut meats for oil to make cosmetics and we would get the coconut meat meal. Wow! That was great! Seaweed has been used often by other gardeners. All of this is good.

I add my organic matter to the top of my beds twice a year. I do not dig it in (wouldn't be able to call it 'no-dig' then would I?). The 'organic matter' I used comes from my compost piles or from the LA Department of Sanitation. I pile on layers of the stuff – about 3 inches twice a year. I have seen 'double-diggers' fill the bottom of their double-dug trench with organic matter. Once they were done with their beds, they were two spade-lengths above ground.

Another aspect to my method is that I don't use any fertilizer at all. I haven't for over nine years. In my opinion, it is bad for the long-term fertility of the soil. What I want for soil is to build up the organic matter in the soil attracting the soil biota that digest all this organic matter. As they digest this stuff, they create the elements essential to plant growth. Adding fertilizer either kills them or harms them in such a way as to render their ability to enrich the soil setting up a vicious cycle where you have to add fertilizer because nothing will grow, so you don't stop to allow the microbial activity to reach a self-sustaining level. One way, you spend lots of money on fertilizer and in the other, you don't. The fertilizer crowd gets their crop the very first year, the non-fertilizer crowd has to wait for year or even year three.

Being a gardener requires patience. It is not a virtue anymore: It is essential.

david



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