Nutrient Cycles

Question 1

Order of decay soc

Answer 1

Sugars and starches (fastest)
Crude proteins (second fastest)
Hemicellulose (middle of the road)
Fats and waxes (slower)
Lignins and phenols (slowest)

Question 2

Active pool c

Answer 2

Liable, easily decomposes, lower c/n ratio, living biomass, food for most organisms, especially r strategists

10-20% or total c pool

Question 3

Slow Pool c

Answer 3

Slowly decomposing, high lignin, chemically persistent, half life of decayed, feeds k stratagists

Height c to n
Minor component of c pool

Question 4

Passive pool c

Answer 4

Stable som, 100s to 1000s of years, 60-90% soc
minerals

Question 5

Som on global atmospheric co2 levels

Answer 5

Plant matter broken down, much is released into atmosphere. Some is incorporated into the soil as SOM

Healthy soils with more com is better for atmosphere

Question 6

Soil organic carbon

Answer 6

Portion of som occupied by c

Question 7

Som

Answer 7

C,h,o,n,p,s and other stuff
Dead tissue, wastes from consumers

Question 8

Inorganic soil carbon

Answer 8

Carbonates from parent material and 2dary accumulations of pedogenic calcite’s
-can be bug in deserts

Question 9

Sequestration and release of carbon from soils

Answer 9

-microbial activity, breaks organic matter down and stabilized in soil
-inaccessible in microgregates
-Fire: bio char is more stabilized
-agriculture and land use!!! Deforestation, type conversion can be badddd
-when respiration is slowed down in cool and wet environments
Histosol, Gelisols, maybe mollisol

Question 10

Processes affecting decay

Answer 10

-Location and enviro factors: surface vs subsurface, temp, moisture, oxigen, ph

Particle size

Hydrophobicity and molecular chemistry

C:N Ratio

Question 11

K strategist

Answer 11

Slowly mobalizing slow pool recalictant stuff,

Uptake as r dies off

Question 12

R stratagists

Answer 12

Boom and bust

Ravers

Explodes as labile sugar rich material hits ground, dies off as its broken down

Question 13

C:N ratio

Answer 13

Dictating decomp rate

Most dry plant matter : 42% C, <1-6% N

Plants
Legumes are 10:1 to 30:1
Sawdust is 600:1

Bacteria
Less variable and lower than plants
5:1 to 10:1
Bacteria have more protein then fungi

Question 14

C:n ratio over 24:1

Answer 14

Microbes scavenge for n, take it away from plans
-slowed decay, nutrient problems w plants

Question 15

N depression

Answer 15

Depending on how you add residues, their composition

If you put in high or intermediate c to n stuff… nitrogen goes down as microbes pull nitrogen from soil… creates depression of nitrogen

So you want to put in plants with low c to n (more nitrogen) to avoid the issue

Question 16

Ch4

Answer 16

Methane is a greenhouse gas, produced by microorganisms in anaerobic environments as they breakdown om. Wetlands, rice paddies. bad greenhouse gas

Question 17

Nitrogen

Answer 17

Chemical element

Nitrogen gas

Neutral

Question 18

Nitrite

Answer 18

No2-:

Usually transformed from ammonia, transformed into nitrate after

Fairly oxidized

Question 19

Nitrate

Answer 19

No3-

Taken up by plants, along with ammonium

Transformed from nitrates, taken up by plants

Most oxidized

Question 20

Ammonium

Answer 20

NH4+

Available to plants
Most reduced

Ammonification, as it turns from nitrogen in atmosphere to ammonium through nitrogen fixing bacteria

Question 21

Ammonia

Answer 21

NH3, same compound in ion form

Also really oxidized

Question 22

N2o, No

Answer 22

Nox

Question 23

Immobilization/assimilation

Answer 23

Inorganic nitrogen to organic nitrogen

Question 24

Mineralization

Answer 24

Organic form to an inorganic form

Question 25

Ammonification

Answer 25

Volitization of organic n an ammonia or ammonium, can be lost from soil Done by soil bacteria

Question 26

Fixation

Answer 26

Soil fixing Bacteria absorb nitrogen from the atmosphere , than converted to ammonia through Ammonification

Question 27

Nitrification

Answer 27

Ammonia contributed to nitrite and nitrate Oxidation or NH4 to NO2- or NO3-

Question 28

Denitrification

Answer 28

Nitrite to nit ate to gaseas nitrogen, lost from the soil Reduction of no2- n03- to n2, n20

Question 29

Ammonia volitization

Answer 29

Loss of nitrogen into atmosphere

Question 30

Microbes and soil organisms in n process

Answer 30

Medite entire process Nonsymbiotic (independent organisms) and symbiotic (mutually benefiacial plants and microbes) Non symbiotic: azotobacter, clostridium, Symbiotic: I care host plant roots, make nodules… rhizobia, Frankie Nitrosomonas: oxidize nh4 to no2 Nitrobacter: nitrite to nitrate

Question 31

Leghemoglobin

Answer 31

Compound made from nitrogen fixing bacteria in soil root nodules

Question 32

Oxigen conditions

Answer 32

Nitrite to nitrate is through oxidation!!

Question 33

Nitrogen Excess

Answer 33

Eutrophication Drinking water quality

Question 35

Phosphorus cycle

Answer 35

weathering of rocks releases inorganic phosphate, Plants uptake phosphate ions in ss Decomp: organic p from plant/ animal remains are mineralized by microbes Immobilization: microbes temporarily lock up p Absorption and precipitation. Can react with minerals, be absorbed (?) and become less available

Question 36

Phosphorus key stuff

Answer 36

Availability: only so much is available at one r Solubility:: poorly soluble in water; strongly absorbed to clay and metal oxides Quantity: usually small fraction of the p is plant available

Question 37

Phosforous too much

Answer 37

Eutrophication, soil imbalance and interfering w uptake if other stuff

Question 38

Phosforous deficiency

Answer 38

Critical for root development, energy transfer, genetic material Leads to stunted growth, delayed maturity, discoloration (purple)