Soil contains particles of clay, silt and sand. Clay particles are tiny and porous, allowing them to absorb water and nutrients. Silt increases the soil's liquid capacity, while sand permits the drainage of excess water.
These minerals provide most of the essential nutrients that plants need. Water serves as the carrier of these nutrients and enables the process of photosynthesis. Photosynthesis also requires carbon dioxide, which is found in soil air. The last component of soil is decomposed plant and animal residues, also known as organic matter. Organic matter helps form soil aggregates, which are essential for improving soil structure.