There are many types of soil. The ones below are the most common ones. Soil type provides the structure of the soil and this determines things such as water and nutrient/mineral exchange and retention and the capacity of the soil to resist erosion and/or compaction, among other things.
Soil type cannot be changed in big areas, but the structure can be improved by adding organic matter.
Sand: improves drainage which means that has poor water holding capacity. Sand adds nothing to nutrient availability to plants either. Sandy soil feels gritty. It drains easily, dries out fast and is easy to cultivate. Sandy soil warms up fast in spring and tends to hold fewer nutrients as these are often washed away during wetter spells. Sandy soil requires organic amendments such as glacial rock dust, greensand, kelp meal, or other organic fertilizer blends. It also benefits from mulching to help retain moisture.
Silt: excellent water holding capacity also makes water available to plants as pore space is big enough to allow the roots to explore. Silty soil feels soft and soapy, it holds moisture, is usually very rich in nutrients. This is a great soil for your garden if drainage is provided and managed. Mixing in composted organic matter is usually needed to improve drainage and structure while adding nutrients.
Clay: Clay soil feels lumpy and is sticky when wet and rock hard when dry. Clay soil is poor at draining and has few air spaces. The soil will warm up slowly in spring and it is heavy to cultivate. excellent water holding capacity and excellent for nutrient exchange, but availability of both water and nutrients to plants may be moderate to poor as pores are too small for some roots to penetrate.
Peaty: Peaty soil is a darker soil and feels damp and spongy due to its higher levels of peat. It is an acidic soil which slows down decomposition and leads to the soil having fewer nutrients. The soil heats up quickly during spring and can retain a lot of water which usually requires drainage. Drainage channels may need to be dug for soils with high peat content. Peat soil is great for growth when blended with rich organic matter, compost and lime to reduce the acidity. You can also use soil amendments such as glacial rock dust to raise pH in acidic soils.
Loamy: Loamy soil, a relatively even mix of sand, silt and clay, feels fine-textured and slightly damp. It has ideal characteristics for gardening, lawns and shrubs. Loamy soil has great structure, adequate drainage, is moisture retaining, full of nutrients, easily cultivated and it warms up quickly in spring, but doesn’t dry out quickly in summer. Loamy soils require replenishing with organic matter regularly, and tend to be acidic.
Soil tests you can do yourself:
The water test
Pour water onto your soil. If it drains quickly it is likely to be a sandy or gravelly soil, on clay soils the water will take longer to sink in.
Grab a handful of soil and softly compress it in your fist.
Add a handful of soil to a transparent container, add water, shake well and then leave to settle for 12 hours.
Resources for local soil tests and info: http://www.rootshootdesign.com/