So, here’s another post about roots. This time, I want to talk about how deep soil preparation (double-digging) works to increase the health and yields of plants by giving them room to spread out.
Did you know that the average carrot puts down an 8-foot-deep root? It’s true – check out the picture on page 19 of the 9th edition of How to Grow More Vegetables! The more root a plant has, the more nutrients it can take up. More nutrients means healthier plants, higher yields, and more nutritious food for you and your family.
Typically, farm soil is only prepared 6-inches deep. However, the Royal Horticultural Society in England performed tests showing that soil prepared 24-inches deep – the same depth that results from the “double-digging” method that Biologically-intensive gardening uses – produced healthier plants and higher yields. When you prepare the soil four times as deep as “normal” (24 inches) you produce four times the root system and four times the nutrient-cycling occurs! See what happens in the soil when it is prepared 10-inches deep (upper image) and 20-inches deep (lower image) in the photographs to the left. These images are from the section “Living Quarters for Plant Roots—A Picture Story of How Soil Conditions Determine Root Development” by Henry C. De Roo. This is from the Brooklyn Botanic Garden out-of-print Handbook on Soils, 1956, which has been reprinted by Ecology Action with its kind permission (also available on Amazon). Which rooting system would you rather have growing your food- and compost-crops?
Now, I know that people can be a little doubtful about double-digging, because it seems like “work”. But Biologically-intensive gardening and farming is not really labor intensive…it is actually skill intensive! You do not need to work harder, you just need to think smarter! See p. 30 in HTGMV. Think of double-digging as an investment, that once made, will continue to repay you and your garden to as long as you maintain it correctly. You do not have to continually double-dig. Once good, deep soil preparation has been established for a sufficient time, you only need to surface cultivate 2- to 4-inches deep with a hula hoe. See pp. 14=32 in HTGMV for the overall process.
Good soil preparation increases the quality and quantity of your gardening and farming result!
Give double digging a try – even if it’s only one bed to start with. You won’t be disappointed, and your plants will love the extra space to sink their roots.