1. APES

2. 6 Major components of soil Eroded rock Mineral nutrients Decaying organic matter Water Air Living organisms 3. Importance of Soil Provides nutrients Recycles/filters water Stores water Soil is the basis of life on Earthwhy do you think? Plants get nutrients from soil and plants provided glucose and oxygen (producers) 4. Terms associated with creation ofsoil Infiltration Downward movement of water through the soil Leaching Dissolving of minerals and organic matter in upper layers carrying them to lower layers***soil type determines degree of leaching and infiltration 5. Formation of Soil (clay + mix ofdead vegetation) Physical weathering Mechanical weathering Any process that breaks down rock into smaller pieces without changing chemistry of rock Wind and water Chemical Weathering Result of chemical interactions between water and atmospheric gases and the bedrock of the region Oxidation: reaction with O2 Hydrolysis: rxn with H2O Acid action: Rxn with acids (H2CO3, H2CO4, H2SO3) Dissoultion: chemical weathering from acid rain Biological weathering Takes place as a result of activities of living organisms Can be combined with chemical processes Chemosynthesis of bacteria Roots of trees creating fissures in rocks exposing them to further mechanicaland chemical weathering 6. Soil 1 gram of soil has over 50,000 protozoa as well asbacteria, algae, fungi, earthworms and nematodes Pores between grains of minerals in soil are filled withair or water Plants need water and oxygen Need to make glucose-use photosynthesis and cell respiration Size of the particles that make up the soil determine thesize of the pores between the soil particles USDA has many ways to categorize Color Texture 7. Soil Horizons O horizon (surface litter) Uppermostorganic matter (leaves, twigs, crop waste, animalwaste, organic matter) Dark, crumbly material that results from decomposition oforganic matter Brown or black A Horizon (Topsoil layer) Porous mix of HUMUS and some inorganic particles (weatheredrock) LEACHING/ELUVIATION zone Fertile soil=better crops Holds water and nutrients for plants *** O and A are anchored by vegetation B Horizon (subsoil) Composed of inorganic minerals Broke down rock (clay, silt, sand/gravel) Receives all minerals leached out of A horizon as well as organicmaterial that is washed down from the topsoil above ILLUVIATION/ACCUMULATION zone accumulation of soluble or suspended organic material, clay, iron, or aluminum C Horizon (parent material) Large pieces of rock that have not undergone much weathering R Horizon Bedrock 8. Soil Textures-3 major divisions Clay Smallest, very fine Less than 0.002mm in diameter Easily stick to each other Little room between particles to store water Extremely compact, feels sticky Silt 0.002-0.05 mm in diameter Feels smooth Holds water well Resists filtration Sand 0.05-2.0 mm in diameter Coarsest particle Too large to stick together Creates soil with large pores Water filter through (Gravel) 2.0 mm and larger Does not hold water well 9. Acidity and Alkalinity of Soil What is pH? Most soils pH= 4-8 (neutral to slightly acidic) pH affects solubility of nutrients Determines nutrient availability for absorption by roots ofplants If soil in a region is too acidic or basic, certain soil nutrientsin that region will not be able to be taken up by plants pH too acidic=BIG problems Ions of heavy metals mercury (Hg) or aluminum (Al) can leachinto the groundwater These ions will then travel to streams and rivers=negativeimpact to plants and aquatic life Ex. Aluminum ions can damage fish gills=suffocation of fish 10. Loamy Soil composed of roughly thesame amount of all three textures(clay, silt, sand) and organicmatter Loose and rich When you squeeze it, forms a ballthat crumbles when poked Good at absorbing and storingwater Best for plant growth 11. Soil Types- Based on Water content Pedocal Dry, semi arid climate Little organic matter No mineral leaching High limestone content praries Pedalfer Enriched with aluminum and iron Greater organic matter and leaching Found in areas with high temp. and lots of forest cover Laterite Soggiest type Tropical and subtropical climate zones High organic matter Low nutrients (lots of rain) Aluminum hydroxide=red soil 12. Soil Porosity Measure of the volume of pores or airspaces per volume of soil AND averagedistance between those spaces Fine particles help retain water (precipitation goes into pores) Large particles help create air spaces for filtration Pores b/t organic solid particles andinorganic solid particles in upper andlower layers Contain varying amounts of air (N andO) and water Porous soil Many pores Can hold more water Non porous soil Not a lot of spaces Cannot hold much water 13. Soil Permeability Rate at which water and air movethrough the soil Sand High permeability Water moves through quickly Filters water Clay Low permeability Water moves through slowly Retain water 14. Topography Mapping of the land by contours and physical features of areas Since water runs downhill, it is easy for soil to be carried away during a heavyrainstorm Slope percentage affects the speed of the waters down hill path Ex. 5% grade= more erosion than 1% grade 15. Soil Formation is influenced by 5interrelated factors 16. How Soil is Formed 17. Soil Problems For and Caused By Humans Properties humans look for in soil Top soil Nutrient rich soil layer, millimeters to meters deep Contains a mix of organic matter and minerals Renewable when replenished and cared for properly Currently, thousands of acres bare due to erosion, nutrient deficiency,overtillage, and misuse Arable: soil suitable/fertile for plant growth Fertility refers to soils ability to provide essential nutrients: N, K, andP Humus also important b/c its rich in organic matter Loamy soil Composed of same amount of clay, silt, sand Ability to aggregate (clump) Best soils are aggregates of different soil types bound together byorganic matter 18. Tillage Repeated plowing Breaks down soil aggregates leaving plow pan or hard pan (hard, unfertile soil) Opening up Earth to plant new seeds Increases soil erosion It is done b/c it is thought to increase soil nutrients Today, narrow chisel plows are used that leave 75% of crop residue on surface and open up only a thin ridge for seeds No-till methods are beneficial Pierce seeds through ground cover without opening up a seam in the earth Keeps soil in place and prevents erosion 19. Monoculture Planting of just one type of crop in large area Decrease in genetic diversity of crop species Lack of genetic variation=increased susceptibility to pests and diseases Consistent planting of one plant in area LEACHES soil of specific nutrients needed for plant growth Prevention Method: CROP ROTATION Different crops are planted in growing area in each growing season Machinery Large machines Agriculture industry is a huge consumer of energy Energy is consumed by: Production of pesticides Production of Fertilizers Use of fossil fuels to power farm machinery 20. Green Revolution=boom in agricultural productivity Industrial revolution mechanization of farming increase worldwide agricultural productivity in last 50 years of =detrimental toenvironment Drawbacks Increase in irrigation = Over irrigated soils= SALINIZATION Soil becomes water logged and when it dries out, salt forms a layer on the surface, which leads to land-degradation Drip irrigation is one way scientists have started combating problem Allots area only necessary amounts of water Water delivered straight to roots Chemical pesticides=new insect species that are pesticide-resistant Recently GM plants are helping solve pesticide problem 21. Soil Erosion Bare soil=soil in which no plants are growing More susceptible to erosion than soil covered by organic matter Erosion: normal and natural process Constant movement of wind and water on Earths surface Drawbacks: Removes valuable top soil Over 25 billion tons of soil lost due to wind and water erosion Erosion can lead to DESERTIFICATION Deposits soil in undesirable places (i.e. bodies of water) Farmers need healthy soil for planting Humans rely on water uncontaminated water for drinking/living Soil can contaminate water with pesticides and other harmful chemical Causes Deforestation logging and slash-and-burn Plants anchor in O and A horizons of soil Removal of plants make soil susceptible to erosion Over-cultivation of agricultural fields Overgrazing Urbanization***All of these will continue to make ARABLE land for farmers hard to find***New techniques must be utilized to preserve the integrity of the soil 22. Effects of Erosion Top soil blown away by wind or washedaway by rainfall Weakened land Leads to Downstream flooding Reduced water quality Increased river and lake sedimentation Build up of silt in reservoirs andnavigation channels Dust storms Health issues Allergies Eye infections Upper respiratory problems 23. Soil Conservation Several management practices utilized to conserve soilresources 1. Return organic matter to soil 2. Slow down effects of wind 3. Reduce amount of damage done to soil by tillage (plowing) Examples: Use animal waste and the residue of plants to increase the amount of organic material in soil Modify tillage practices to reduce the breakup of soil and reduce the amount of erosion (contour plowing and strip planting) Use trees and other wind barriers to reduce forces of winds 24. Soil conservationContour planting Plant across a hillside (instead of up and down),slows run off Strip farming Planting alternating crops in strips across land In combination with contour planting, this slows erosion Terracing Similar to strip farming Land is shapedlevel ridges of land are created to hold water and soil in place More expensive and time consuming but allows cultivation on steep grades and increases sustainability (this is how rice is grown in Asia) Perennial plant growing Coffee and tea Plants that grow during several seasons Do not have to harvested yearly AND hold soil longer Ground cover plants (alfalfa) hold and protect soil from erosion if planted right after initial harvest 25. Soil Laws 1977 Soil and Water Conservation Act Soil and water conservation programs to aid landowners and users Sets up conditions to continue evaluating the condition of the US soil, water and related resources 1984 Food Security Act Swampbuster Act Discouraged conversion of wetlands to non-wetlands 1990 federal legislation denied federal farm supplements to those who converted wetlands to agriculture Provided restoration of benefits to those who unknowingly converted lands to wetlands 26. Prepared by:Chasey Gabrielle CiudadKathleen BaesRonna Badoles