Element

1. Element / Nutrient Cycling in the Soil

2. Why study nutrient cycling? nutrient supply is a primary control on GPP, NPP, decomposition, and trophic interactions human impacts on nutrient cycles (fertilizer use, fossil fuel combustion, cultivation of N-fixing crops) are large enough to impact the global carbon cycle some gaseous products of nutrient cycling reactions directly influence atmospheric chemistry / pollution some gaseous products of nutrient cycling are greenhouse gases

3. Organisms Chemical Requirements Carbon: Besides water, carbon source is one of the most important factors for organismal growth. About 50% of dry weight of a organismal cell is carbon. Chemoheterotrophs get carbon from organic materials. Chemoautotrophs get carbon from CO2. N, S, & P: Total 18% dry weight. DNA, RNA, amino acids, proteins and ATP Algea: Nitrogen fixation. Trace elements: Fe, Cu, Mo, Zn, Co, Ca, Mg, Mn, Ni, Se, total 2%. These serve as enzyme cofactors.

4. Important Element / Nutrient Cycles Carbon Cycle Nitrogen Cycle Phosphorus Cycle Sulfur Cycle Metals Cycles

5. Carbon

6. The Significance of a Carbon Can bond to four neighboring atoms Can bond to other carbon atoms, sharing one, two, or three electrons These properties make it possible to form a vast array of organic molecules No other element has these properties

7. Monomeric Carbon Compounds Organic acids � Carbohydrates � Amino acids �