Soil

1. Soil

2. Nutrients • Nitrogen- controls formation, makes proteins • Lack of nitrogen- spindly, stunted growth • Too much- disease susceptible • Phosphorous- helps photosynthesis and respiration, increases growth rate • Lack of phosphorous- spindly thin stems • Since its difficult to obtain, too much is basically impossible • Potassium- helps metabolize food for energy • Lack of potassium= weak roots, burned look to plants, cannot regulate water

3. Soil Facts & Definitions • Gleyed= mottled • Dust Bowl of 1930s- First indication that soil is important • Colluvium- soil accumulated due to slide • Karst- topography with sink holes due to limestone • Loess- wind deposit of soil • Piedmont- low plateau from NJ to AL east of Appalachains

4. Soil Structure • Determined by size, shape, and grade • Grade: Weak, Moderate, Strong • Shape: Granular, Prismatic, Subangular blocky, Angular blocky, Platy

5. Soil Organisms • Bacteria- mostly around roots, in litter, on humus, on surface and between soil aggregates • Activity level follows seasonal patterns • Grass and soil ecosystems have bacteria based food chains • Forest have fungal based food chains • Food web complexity based on number of species and number of types of species

6. Benefits of Soil Complexity • Nutrients cycle • Nutrients are retained • Structure, infiltration, and water holding capacity improve • Diseases are decreased • Biodiversity increases

7. Bacteria types • Decomposers- organics and pollutants • Mutualistics- live on plants • Pathogens- such as gall formers • Lithotrophs or chemoautotrophs- cycle nitrogen, break down pollutants

8. Important Bacteria • Nitrogen-fixing bacteria- transform gaseous nitrogen to nodules • Nitrifying bacteria- change ammonium (NH4+) to nitrite (NO2-) then to nitrate (NO3-) the preferred form of nitrogen for plants • Denitrifying bacteria-nitrate to nitrogen (N2) or nitrous oxide (N2O) gas (anaerobic processes) • Actinomycetes- decompose ahrd to decay plant material