Topic 8) Soil Organic Matter Flashcards
Influance of Carbon
CEC
Water capacity
Soil Aggregates
Nutrients storehouse
Soil quality and fertility
Global carbon balance
Soil Carbon Storage
Most Carbon is stored within the soil
Decomposition in Organic Soils
1) Oxidation
Enymes oxidize carbon compounds.
2) Release
Essential elements are realsed
3) Synthesis
New Compounds created by mircobes
4) Protection
r-stragtegists
Quick popultion increase with increase of organic compounds then decrease after it has all been consmued
k-strategists
Longterm organism thats populations do not explode when increaecd amount of organic matter is added to the envirement
Rates of Decompostions and Mineralization
Enviromental Conditions in the soil and Quailiy of added residues
Compostion Rates of Plant residues
the more simple the compound the faster. The more complex the longer it will take.
Carbon to Nitrogen Ratio
1) compettion for available soil nitrogen
2) Determines rate of decay and nitrogen availability
SOM vs SOC
Labile C is accessble to plants and organism. Humus is super stable and is not acessable by plants.
Formation of Char.
Produced by smouldering and charring under low oxygen condtions. Contains alot of Carbon
Influcances of OM on plant growth.
Direct influcance (availability of nutrients)
Allelochemical effects
(plants can impact the growth of others)
Soil physical properites
(water retention, CEC capacity, food).
Levels of OM and SOC in natural ecosystems
Forests:
Increased biomass
OM oxidation is much slower
Increased Leaching
Deacreased erosion
Grasslands
Large role of plant root biomass
Decays More slowy. SOC distruted more uniformly the in forsts
Frequent fire
Wetlands
Very high productivity
Lack of Oxygen
Impacts of climate change on soil
Changing Balence between gains and losses
Active vs stable fractions of SOM
Solutions to Climate Change
Reforstatsion
Converson of cultivated land to pereniial vegation
Reducing tillage
Artic Carbon Stores
Soil in the artic contain alot of stored carbon
