Lesson plan
Double digging
Double digging is a gardening technique used to increase soil drainage and aeration. It involves the loosening of two layers of soil, and the addition of organic matter. Double digging is typically done when cultivating soil in a new garden, or when deep topsoil is required. On poor or heavy soils, or for vegetable gardens, double digging might be required every 3–5 years. In other cases, double digging is only really needed when starting a new garden, or on total replanting. First the top layer is dug off with a spade, forming a shallow trench, and then the under-layer (at the bottom of the trench) is dug with a fork. When breaking up the lower layer, organic matter such as compost is usually added to the soil. If the soil is in need of other minerals like gypsum or phosphorus, this can also be added here. A second trench is then started, backfilling the first trench. This process is repeated until the whole bed has been treated. There will be soil left over from the first trench, which is used to fill the last trench. Walking on top of the bed will tend to compact it, so the gardener must be sure to protect the soil from too much foot traffic.
Article summary
Double digging is a gardening technique used to increase soil drainage and aeration. It involves the loosening of two layers of soil, and the addition of organic matter. Double digging is typically done when cultivating soil in a new garden, or when deep topsoil is required. On poor or heavy soils, or for vegetable gardens, double digging might be required every 3–5 years. In other cases, double digging is only really needed when starting a new garden, or on total replanting. First the top layer is dug off with a spade, forming a shallow trench, and then the under-layer (at the bottom of the trench) is dug with a fork. When breaking up the lower layer, organic matter such as compost is usually added to the soil. If the soil is in need of other minerals like gypsum or phosphorus, this can also be added here. A second trench is then started, backfilling the first trench. This process is repeated until the whole bed has been treated. There will be soil left over from the first trench, which is used to fill the last trench. Walking on top of the bed will tend to compact it, so the gardener must be sure to protect the soil from too much foot traffic.
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Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
Bibliography
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Key claims and bibliography are generated from the same tracked claims and sources as the article page.