 Soil is formed over a VERY long period of time.  As solid rock is weathered into tiny pieces as a result of: ◦ freezing and thawing ◦ having water wash over it by rivers and waves ◦ glaciers moving across rock  The tiny fragments of rock form the first layer of soil. As the layer becomes thicker and thicker, soil beings to form.

 Soils can take hundreds, thousands, to millions of years to form.  The type of soil that will form is dependant on the climate, location, vegetation and time.  It is also dependent on the parent material, which is the rock that the soil forms from.

 Soil is composed of 4 main things: 1)Minerals – tiny fragments of rock 2)Air 3)Water 4)Organic Matter – leaves, roots, and small living organisms.

 The organic matter is the main source of food for plants growing in the soil.  The air is found in the spaces between the mineral matter and help the plant roots to breathe.  Water is used by the plants and helps to move food to the roots.

 Soil is an important resource as majority of food sources (other than aquatic) are traced back to soil.  Think of a hamburger and all the ingredients, how many can be traced back to soil?  Soil is considered non-renewable because it takes so long for productive soil to be formed.

 Even though soils can be very deep, the most important part is the surface, cm down.  This portion is called topsoil and will be most likely dark in colour, almost black.  The dark colour shows that there is a lot of organic matter present.  Even if fertilizer is added to a poor top soil,the plants will still not grow to full potential.

 Subsoil is the next layer below the topsoil.  It is usually lighter in colour.  Fewer living things are here because there is less organic matter and food for plants.  Under the subsoil is the parent material.  This is made of rock, dust and gravel.  There are no living things in this layer, as there is no organic matter.  Formed as the bedrock underneath breaks down.

 Horizons – typically there are 4.  O-horizon: leaf litter and organic material.  A-horizon: Top soil  B-horizon: Sub soil  C-horizon: Parent material  R-horizon: Bed Rock

 The soils that agriculture has been using have been there for thousands of years.  When land is first cleared and planted, the soil is typically very rich in nutrients and organic matter. Crops and plants will grow well here.  However, as time passes and more crops are planted, the soil becomes poor.  This means it loses some of the organic matter present and produces less and less food.

 These plots were eventually abandoned and more plots were cleared.  The abandoned plots were left uncovered and unprotected. This creates soil degradation.  Soil degradation is the wearing out of soil.  As soil derogates, it loses it’s ability to grow food/forests and support livestock/wildlife.

 Salinity is a type of soil degradation.  Salts build up in the soil.  They appear as white patches on the soil.  Salt can be deposited at the top of the soil due to the water underneath. As salty water is pushed to the surface and evaporates, salt is left.  High uses of potassium fertilizer can cause soil salinity.

Solutions to Soil Salinity:  Keep plots watered.  Stop using fertilizers.

 Today our soils contain about half the amount of organic nutrients that they used to contain.  This is due to clearing areas for agriculture, taking away natural plants and forests.  By constantly planting crops and not allowing soils to ‘regenerate’, organic matter loss only increases.  Too much tillage can also cause a loss in organic matter as it disturbs the natural plant life.

 Growing grasses and alfalfa (crops called forages) allow nutrients to be added back to the soil.  Adding natural fertilizer, such as manure.

 When a strong wind blows on bare soil, loose material is blown away.  Most of this material will accumulate in other areas, such as along fences or in ditches.  Lighter soil material is lost as dust into the atmosphere.  If too much soil is blown away, any plants growing there will be damaged, some beyond repair.

 The best way to prevent soil erosion is to keep soil surface covered.  Soil can be covered with grass, straw, stubble, trees or a crop to protect it from the wind.  By not tilling soil (mixing soil) in the fall, which is typically windy, leaves more soil behind.

 Continuous Cropping – Never allowing a field to be bare, always having a crop growing there.  Shelterbelts – Rows of trees to slow the wind.  Strip-cropping – Seeding narrow strips of crops prone to erosion, such as sugar beets, alternating with strips of crops that are erosion resistant, such as wheat.

 Water erosion occurs anytime water flows across bare soil.  This is especially apparent on a steep or long hill.

 1) When raindrops fall, they tend to explode out, like a bomb – called splash erosion, and the 1 st step in water erosion.  2) After rainfall continues, water begins to run down the hill and will pick up pieces of soil with it and wash them away – called sheet erosion and is the 2 nd step in water erosion.  3) If the rain continues for a long period of time, small paths will be cut in the soil, creating tiny rivers – called rills and are the 3 rd step in water erosion.

 Soil can be protected from rain by keeping it covered with straw, grass, stubble or crops.  Rows of crops can be planted across the slope of a hill.

 The packing down of soil by forces of weight on the surface.  It occurs when heavy equipment (such as trucks and farming equipment) travels across the soil again and again.  Compaction will slow or prevent good root growth.

 Stop driving the equipment over the soil (duh!)  Tilling up the compacted soil and replanting will allow nutrients to be added and soil to become more aerated.

 Occurs when unwanted chemicals build up in the soil.  Main cause is the overuse of pesticides.  This causes ‘Non-point source pollution’, a type of pollution where the exact source cannot be pinpointed.  The leaching and traveling of these pesticides can end up in places such as drinking water reserves and rivers

 Use only organic pesticides or release insects that will combat the pest you are trying to get rid of.  Create reservoirs around the property to catch any run off.  If pesticides must be used, regulate amounts.

 When land gets so worn out from farming or soil erosion over time, it will turn into a desert waste land.  It is not longer viable for plant growth.  This usually occurs where long areas of drought have taking place, such has countries in Asia and Africa.

 Allowing land to ‘rest’ and rejuvenate over many years.  Irrigating land and planting nutrient adding crops, such as grasses.