Soil is the first layer of the surface of the Earth. It is made up of rocks, plants and animal matter that have decayed and weathered to form a thin layer of soil. Soil is one of the most important elements in gardening, with the others being water and sun. Soil is classified by its texture and the proportion of sand, silt or clay it contains. Texture refers specifically to soil particle size as opposed to the organic matter contained in the soil. There are four main types of soil with each one offering its own benefits and weaknesses in the health of your garden.
Sand is gritty and consists of very small particles of rock and minerals. Sand is formed by the weathering of rocks, such as granite, shale, quartz and limestone. Sand warms faster than most soils. This type of soil drains well so plants don't get waterlogged; on the other hand, plants are unable to retain water and may die from dehydration during the hotter months.
Silt is a very fertile soil. It has a smoother texture than sand but looks like dark sand when it is wet. It is comprised of minerals like quartz and other particles. It is similar in composition to sand, but it contains more nutrients and can hold more moisture. It is easy to work with even when it is wet.
Clay is very fine grain soil with little air space. This soil is considered the most difficult soil to work with. The drainage in this soil is low and most plants become waterlogged if planted in this type of soil. It also compacts very tightly, giving plants the inability to establish their root systems. If wet, this soil is very difficult to loosen. It is easier to work with the soil when it is dry, which is when you will want to amend the soil so your plantings can thrive.
Loam is considered the perfect soil. This soil is a combination of sand, silt and clay. This soil is gritty and retains water while also having good drainage. Loam is considered the best to grow most any type of plant.