Soil Composition Fertilizer

Soil  Loose covering on the ground containing a mixture of organic matter, minerals and moisture

Soil quality  Soil profile  Soil type  acidity

Soil Profile SoillayerComposition TopsoilUpper  Humus (decaying organic matter)  Rock particles  Organism (bacteria, fungi, insect, worms) Subsoilbelow top soil  Compact  Little or no organic matter excepts bacteria and roots of very large trees  Contains water table (top surface of ground water) bedrockBottom  Solid rock  Water cannot pass causing bottom of subsoil to get saturated

Airspace  allow water and nutrients to pass through to reach roots  Provide oxygen to root and organisms  Dependent on particle size

Compaction  Pressure squeeze soil particles closer  Caused by heavy equipment or people walking  Roots may not obtain enough oxygen  Water have difficulty passing through soil

Soil Types SoilParticlesDescription LoamRock of many different sizes  Pockets to hold air or water  Keeps soil loose so plants can grow in it  Lot of humus  Drains well ClayExtremely small Tightly packed  Prevents air pockets  Block root growth  Trap water  Excessively wet soil SandySand particles Large compared to clay  Large spaces for root growth and air pockets  Water drains carrying nutrients away  Less fertile than loam

Soil Acidity  pH scale from 0 to 15  Neutral is pH 7  Acidic is low pH  Basic is high pH  Most plants and animals prefer neutral environments

Fertilizers  Natural fertilizer: made from plant and animal waste Animal manure Sludge plant material (seaweed, compost) Blood meal, bone meal Wood ash  Synthetic fertilizer: manufactured by humans Ammonia, synthetic urea Potash, potassium, Commercial chemicals

Problems with Synthetic Fertilizer  Nutrients are highly concentrated  May enter soil rapidly and alter community of soil organisms  Lead to soil with less natural organic matter and stressed soil organisms  Soil lose supply of naturally occurring nutrients  Creates dependency on synthetic fertilizers  Susceptible to erosion

Leaching  nutrients become dissolved in water and seep out of soil  Contaminate groundwater  Drinking water with high levels of nitrogen compounds can cause health problems

Algae Bloom  During heavy rain or spring runoff, fertilizer can aquatic ecosystem  Algae bloom: Increase growth of algae in warm shallow ponds  When algae die, bacteria in water decompose it using oxygen  Decrease dissolved oxygen in water  Kills fish and other aquatic organisms

Comparing fertilizer type AdvantageDisadvantage Synthetic  Nutrients release quickly  nutrient can be precisely measured  Easy to apply  Production is energy intensive  Water pollution  Leaching  Imbalance in soil chemistry  Upset balance of soil microorganisms Natural  Not over fertilize  Slow release  Improve soil structure  Benefit soil microorganisms and nutrient cycling  Low concentration of nutrients  Release may be slower than desired  Not easy to measure nutrient quantity  More difficult to apply

Controlling water flow  Irrigation Provides adequate water to farmland  Drainage allow more air to penetrate soil, gives root access to oxygen Converts natural wetlands into fertile farmland