What is Soil? T Webb HHS

What is Soil? - humus: biotic community - organic/biological materials - minerals - clays and silts - “dirt” * contains air and water; is a media for plant growth and life

Criteria for Soil? - naturally occurring - more than 10 cm thick - supports plant growth - contains organic materials - variable composition with depth * Soil - “Giver of all Life” - many cultural differences in appreciation

Statistics and other stuff… - 10% of Canada’s land is agricultural - soils vary within small areas - in a hectare (100 m x 100 m), with a field containing 20 cm depth of soil, the volume will be 2 000 m3. - for good farming, typical soil has a density of 1.40 g/cm3 (1400 kg/m3) - average % of organic material: 2 - 3% - you need 28 000 kg of manure to increase organic materials by 1%; manure is ~ 75% water by volume… - farmers need to put on 3x the amount of manure to make up for the water content.

How long does it take for soil to form? - In N.S. the Pleistocene Glacial age resulted in many depositions of loose till. This occurred ~ 10 - 12 000 years ago. - Parent material takes on average 10 000 years for ~ 50 cm of soil to develop. This data is consistent across Canada. - The rate of topsoil production can be marginally increased by adding peat moss and compost. - soil texture is very important in the classification process, and for understanding development. The texture is based on the percent of sand, silt and clay.

Characteristics of Soil pH porosity humus content temperature water content particle size(s) nutrient levels (K, Na, Mg, C, N2, P4, SO42-, etc) texture compaction depth of layers density depth of soil % composition drainage character location origin of parent material biological activities colour