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Soils 441: Exam B
Terms in this set (32)
The conversion of organic N to inorganic N like NH4+
Processes associated with mineralization
aminization and ammonification
- microorganisms will break down proteins. Aminization will convert the proteins in the residues to amino acids/urea. Thus, organic compounds are further converted into inorganic NH4+ by ammonification
A step in mineralization: conversion of an amino acid to ammonium (NH4+)
conversion of ammonium to ammonia gas
Name several fates of ammonium through ammonification
- converted to No3- (nitrification)
- adsorbed by higher plants (N uptake)
- utilized my microorganisms ( immobilization)
- converted to ammonia (NH3) and released back to atmosphere (volatilization)
The conversion of inorganic N (NH4+ & NO3-) to organic N
If decomposing OM contains low N what is the outcome?
microorganisms will immobilize NH4+ and NO3- in the soil solution. The microbes need N in a C:N ratio.
IN most cropping systems sufficient N is added to compensate for immobilization and crop requirement. If added OM contains high N, immobilization will not proceed because residues contain enough N to meet microbial demand and inorganic N will increase from mineralization of organic N in residues.
conversion of ammonium to nitrate (NH4 --> NO3)
conversion of Nitrate into gas
(NO3 --> N2, NO2, N2O)
conversion of N2 gas into ammonium
Industrial N fixation process of reacting hydrogen and nitrogen gas under high temperatures and pressure to create ammonium.
CO(NH2)2 - Both a natural organic molecule ( animal excretions) and synthetic N fertilizer: Solid fertilizer
N containing, Building block monomers of protein, connected by C-N bonds.
Solid N fertilizer that is hygroscopic and explosive. Commercially banned in the US because it can be used as an ingredient to make explosives
gasesous N; used as a fertilizer and can be directly injected into soil; also can be a reactant in producing other chemical fertilizers
urea ammonium nitriate: liquid fertilizer
sewage sludge that can be dried up and used as a soil amendment. Cannot be used in USDA certified organic farming due to concern of heavy metals and pathogens
Crops grown specifically to accumulate plant biomass and nutrients that are then returned to the soil to promote better soil quality, reduce soil erosion and improve nutrient cycling of the crop rotation.
dead zone / hypoxic
low oxygen areas in the worlds oceans caused by
excessive nutrient pollution from human activities that deplete oxygen required to support marine life on the bottom of the waters.
Process that requires oxygen:
OM mineralization, nitrification, ion uptake by plants, metal oxidation
Process that does not require oxygen:
denitrification, sulfate and metal reduction
Biological N fixation
conversion of N2 gas into ammonium by microogranisms
Symbiotic N fixation
Conversion of N2 gas into ammonium by microorganism in co-dependent relationship with plants. bacteria are incorporated into root structure nodules.
nitrate contamination of ground water can be harmful and beneficial: true of false?
bad- causes methemogobiemia, cancer, diabetes
good- lower blood pressure, meat preservative, antibacterial
Are there wells in WA with nitrate levels that exceed the EPA safe drinking standard of 10 ppm?
Is it possible for organic fertilizer sources such as chicken manure to cause toxic effects to root systems?
What are 2 N sources that are suitable for fertigation?
What are 3 sources of N commonly applied as a granular fertilizer?
Urea, ammonium nitrate, ammonium sulfate
What fertilizer source has the highest N concentration?
Anhydrous ammonia (86%)
Wha 2 forms of N could be lost to the atmosphere?
NH3 ( ammonia) - through ammonium volatilization
N2O ( Nitrite) - leach below root zone
factors affecting nitrification:
- supply of ammonium
- soil pH
- soil temp
- soil aeration
- soil moisture
Rule of thumb for C:N ratio
C/N > 30:1 is net immobilization
C/N < 20:1 is net mineralization
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