April 27, 2011
Grit your teeth. You are not going to like what I am about to explain because it is all work and no play. The GROW BIOINTENSIVE method requires proper soil preparation before first crops are planted. Proper prep means loosening the soil and composting it at the same time. I am not going to talk about fertilizing until later because that comes last.
Apparently composting is CRITICAL to building good soil and necessary, even in the Willamette Valley. GROW BIOINTENSIVE claims 2X to 3X returns on garden output if their methods are followed. They don't make this claim for first year gardens. Or second. Or third. I think you see where this is going. Building soil is a long-term process. I think my garden soil is pretty sound. In fact, I tested it and found it to have a pH of 7.0, a high presence of Potassium and Phosphorus and a poor showing for Nitrogen. Composting is fertilizing. Yes, well-cured compost will build good soil as it has all of the nutrients needed by a vegetable garden, but if you are starting off from scratch as I am, it is going to take a few years for composting to be sufficient. Until then, additional source of nitrogen will be added.
The process of Double-Digging garden beds involves loosening the soil to a depth of 24" and mixing in 2 inches of compost evenly throughout. This is called the Complete Texturizing Double-Dig and is only done once when preparing beds the first year. Don't get too excited, though, the second year is better but not much!
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| Complete Texturing Double-Dig method, "How to Grow More Vegetables", John Jeavons |
Hopefully you can read the text in the image. The image shows a 5x10 foot bed from the side, ground level. The first step is to spread 1 inch of compost over the bed and, using a 4 or 5 tined pitchfork, turn it in to a depth of 12" or the depth of the pitchfork, whichever is shallower.
The trench in Step 4 runs 5 feet long, by 1 foot wide by 1 foot deep. You dig that out with a square-headed shovel (made for digging trenches!) and put the dirt into a wheelbarrow or whatever. Next you add 1 inch of compost to the trench and, using a 4 or 5 tined pitchfork, turn the soil in the bottom of the trench to a depth of 12 inches or the depth of the pitchfork, whichever is shallower.
Tired yet? : ) Wait, there's more! You take a step back and dig another 5x1x1 foot trench, shoveling the dirt on top of the first trench. The trick here is to keep the soil from falling back into your new trench, so expect to pile it up high. Now you put another 1 inch of compost in the new trench and turn that in.
Keep going until you drop dead.
I tried this last weekend on a 10 foot x 4 foot bed that was tilled last year to a depth of probably 18". The soil wasn't too bad. Not compacted really. I progressed at the rate of 5 feet per hour. Granted I ran 8 miles through Forest Park that very morning and yes I did have 3 or 4 Margaritas at Grandma Shirley's house (they were weak ones. It was Easter brunch). Still, this is real digging so best be prepared.
I plan to Complete Texturize the remaining 300 square feet of garden this spring. That's about another 10-12 hours of digging maybe. Depends on how many Grandma Shirley drinks I knock back first!
