Bedrock is made up of igneous, sedimentary, or metamorphic rock, and it often serves as the parent material (the source of rock and mineral fragments) for regolith and soil. Bedrock is also a source of nitrogen in Earth’s nitrogen cycle.

Erosion happens when rocks and sediments are picked up and moved to another place by ice, water, wind or gravity. Mechanical weathering physically breaks up rock. One example is called frost action or frost shattering.

Soil forms as the solid rock of the Earth, called bedrock, breaks down. It usually takes thousands of years for soil to form from bedrock. In some places, soil forms directly on top of bedrock. In other places, soil forms on a thick layer of loose rock and mineral material.

The main things plants need to grow on bedrock are water, minerals, CO2, and a place to grow roots. Another reason trees can grow directly on bedrock is because they can keep the atmosphere in which they live cool by growing there roots in to the rock which gives off CO2 for the plant to use to grow and keep it cool.

The layers of weathered particles of earth material that contain organic matter and can support vegetation are defined as soil. Soil can be all or just part of the sedimentary material that covers the bedrock. Loam contains sand, silt, and clay with abundant organic material.

Half of the topsoil on the planet has been lost in the last 150 years. In addition to erosion, soil quality is affected by other aspects of agriculture. These impacts include compaction, loss of soil structure, nutrient degradation, and soil salinity. The effects of soil erosion go beyond the loss of fertile land.

Adding organic amendments like composts and manures to soils supports and feeds soil microbes, enabling them to do their work of making nutrients available to plant roots. Vegetable gardeners often need to amend their soil each year, adding back the nutrients that were depleted during the previous growing season.

To improve sandy soil:

1. Work in 3 to 4 inches of organic matter such as well-rotted manure or finished compost.
2. Mulch around your plants with leaves, wood chips, bark, hay or straw. Mulch retains moisture and cools the soil.
3. Add at least 2 inches of organic matter each year.
4. Grow cover crops or green manures.