Garden soil can have a sandy or clay-like texture, but is ideal somewhere in the middle; a fertile, well-drained combination of sand, clay and silt known as loam. Sandy soil is made up of large mineral particles.
The loose, crumbly texture of sandy soil is easy to dig, so it drains quickly, discouraging fungal root rot, but plant nutrients are quickly leached from the soil with each rain. Clay particles are much smaller, giving the soil a heavier, water-holding texture. Clay soil retains nutrients, but drains poorly and is hard to till. Either type of soil can be transformed into fertile loam with generous additions of organic matter. Compost is the finest form of organic matter to work into soil to improve its texture and fertility, but any material derived from decomposed plants, such as rotted hay, grass clippings, shredded leaves, peat moss or rotted sawdust, will improve soil by boosting its organic content.
Because the transformation from less-than-perfect soil to fertile loam involves billions of microscopic soil-borne life forms, which slowly break down organic material into water-soluble nutrients that plants can absorb through their roots, this process takes time. You can make vast improvements in your soil by digging in a four-inch thick layer of compost in one fell swoop, but it’s better to allow two years for results. Before starting a new bed, dig and amend your soil. The first season, plant it with annuals, which will be pulled up at the end of the season. Dig it again in fall, incorporating more organic matter, and by the second spring you will have soil that is the envy of gardeners everywhere.
If, like most gardeners, you already have established beds, or if you can’t devote the time to digging in amendments, applying a layer of compost annually as a mulch on the soil’s surface is the truly care-free way of keeping your soil healthy. Rain and earthworms do the work of incorporating the organic matter into the soil over a season or two, which is exactly what you might expect from a simple strategy that follows nature’s blueprint.
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Transforming soil into loam is worth the time and effort it takes.
