Soil Formation Factors affecting soil formation -the kind and amount of soil developed depends on the following factors the kind of parent material present ( such as the size and chemical nature of thethe particle) the climate(such as temperature) and time involved -the slope of the land the role of the organisms: traps small particles releases chemicals(acid) causing further fragmentation and chemical breakdown of the rock particles contributes to one of the soil components(such as humus )through their death and decay 生命体在土壤形成过程中的作用:网捕细小岩石颗粒;释放化学 物质(特别是酸性化学物质)进一步使岩石颗粒破碎;在自身死 亡和腐化后成为土壤的成分
Soil Formation Factors affecting soil formation –the kind and amount of soil developed depends on the following factors: –the kind of parent material present (such as the size and chemical nature of the the particle) –the climate (such as temperature) and time involved –the slope of the land –the role of the organisms: traps small particles ;releases chemicals (acid) causing further fragmentation and chemical breakdown of the rock particles;contributes to one of the soil components (such as humus ) through their death and decay 生命体在土壤形成过程中的作用：网捕细小岩石颗粒；释放化学 物质（特别是酸性化学物质）进一步使岩石颗粒破碎；在自身死 亡和腐化后成为土壤的成分
Humus-a kind of organic material resulting from the decay of plant and animal remains It is a very important soil component that accumulates on the surface and ultimately becomes the component mixed with the top layers of rock particles, and supplies some of the needed nutrients to plants -Humus increase the water- holding capacity of soil Humus increase the acidity of soil so that the inorganic nutrients become available to plants Humus also tends to stick other soil particle together and helps to create crumbly soil which allows water absorption and permits air to be incorporated into soil(this helps the soils have more pore space)
Humus – a kind of organic material resulting from the decay of plant and animal remains. – It is a very important soil component that accumulates on the surface and ultimately becomes the component mixed with the top layers of rock particles, and supplies some of the needed nutrients to plants. –Humus increase the water-holding capacity of soil. –Humus also tends to stick other soil particle together and helps to create crumbly soil which allows water absorption and permits air to be incorporated into soil (this helps the soils have more pore space). –Humus increase the acidity of soil so that the inorganic nutrients become available to plants
Other Factors Influencing Soil Formation Burrowing animals(Earthworms): resulting further mixing of organic and inorganic material, which increases the amount of nutrients available for plant use; soil aeration and drainage are also improved Plant roots release of organic matter and nutrients into soil and provide channels for water and air Bacteria and Fungi act as decomposers to break down organic material serve as important links in many mineral cycles release nutrients
Other Factors Influencing Soil Formation: • Burrowing animals (Earthworms): resulting further mixing of organic and inorganic material, which increases the amount of nutrients available for plant use; soil aeration and drainage are also improved • Plant roots :release of organic matter and nutrients into soil and provide channels for water and air. • Bacteria and Fungi :act as decomposers to break down organic material ;serve as important links in many mineral cycles;release nutrients
Other Factors Influencing Soil Formation Soil pH: affects the availability of nutrients-affects the kinds of plants that will grow -affects the amount of organic matter added to soil The amount of rainfall: affects the amount of calcium magnesium and potassium are leached from the soil
Other Factors Influencing Soil Formation: • Soil pH: affects the availability of nutrients—affects the kinds of plants that will grow — affects the amount of organic matter added to soil; • The amount of rainfall: affects the amount of calcium, magnesium and potassium are leached from the soil
Soil components 25% Air 45% Mineral 25% Water 5%Organics 5% Organisms 85% Humus 10% Roots