Soil SNC1D

Sand, Silt, and Clay The mineral part of soil is pieces of broken-down rocks. Largest pieces are sand, small pieces are clay, and the intermediate pieces are silt.

Sand, Silt, and Clay These particles in different ratios make different types of loams.

More Than Just Rock Only about 45% of soil is mineral. The rest is: Water (about 25%) Air (about 25%) Organic material (about 5%).

More Than Just Rock Air pores provide oxygen for plant roots. Water dissolves nutrients in the soil, which the roots can then absorb.

Organic Material Of the organic material: 10% is animals 10% is plant roots 80% is humus

Humus Humus is the decayed remains of living creatures, broken down into a crumbly, dark dirt. It holds water in the soil and provides nutrients to growing plants.

Humus Use of chemical fertilizers and pesticides can decrease the humus and nutrients in the soil. Natural Pest Control Chemical Pest Control

The Layers of the Soil Most humus is in the top layer of the soil (often called litter) and the topsoil beneath.

The Layers of the Soil Most humus is in the top layer of the soil (often called litter) and the topsoil beneath. Below the soil is the bedrock.

Topsoil When land is developed, topsoil should be removed to be used somewhere else or it will be mixed up with the other soil components beneath the development and its productivity lost. A topsoil screener for soil recycling

Soil Testing - pH One test measures the pH (acidity) of the soil. Most plants prefer soil that is slightly acidic (between 5.5-7).

pH pH is a measure of the acidity of the soil. Most plants prefer soil that is slightly acidic (between 5.5-7). However, some plants require very acidic soils (less than 4.5) to survive (such as blueberries and azaleas).

pH and Hydrangeas Interestingly, the colour of hydrangeas depends on the pH of the soil.

Soil Testing - Nutrients Healthy soil contains lots of essential nutrients: nitrogen, phosphorus, and potassium (potash).

HOMEWORK Read pages 123-129 Complete page 128 #2-4, 7, 8