Hello to all...
Next Tuesday and Wednesday I will be teaching groups of crop
consultants about soil ecology. I prepared the following 5 questions as a
pre quiz for the crop consultants. How many of you are ready to become
crop consultants ?
Joel
How does infection with mycorrhizal fungi affect crop root function ?
A) Infected roots systems have reduced capacity to absorb water and
nutrients.
B) Infected root systems are less likely to form N fixing nodules.
C) Infected root systems have greater capacity to absorb nutrients and
water.
D) Infected root systems are more susceptible to attack by fungal
pathogens.
What is the primary impact of nematodes and protazoa in
soil ?
A) They parasitize plant roots reducing plant productivity.
B) They graze upon bacteria and fungi, accelerating the cycling of
nutrients immobilized in microbial biomass.
C) They burrow through the soil improving soil porosity.
D) They produce extracellular polymers which bind soil particles into
water stable aggregates.
Which of the following is <
and macroorganisms in soil ?
A) Macroorganisms depend upon enzymes produced by microorganisms to
digest most of the organic compounds found in plant residues.
B) The burrowing action of macrooganisms increases microbial activity
by improving the air:water regime in soil.
C) The shredding of crop residues performed by macroorganisms
increases the rate of residue decomposition by microorganisms.
D) Microorganisms and macroorganisms occupy different pores sizes in
soil and thus have little interaction.
Microbial activity in soil is:
A) Fairly uniformly distributed within the A horizon
B) Concentrated in hot spots around roots, residues and earthworm
tunnels
C) minimal in soils which receive regular applications of soil
pesticides
D) responsible for greatly reducing the plant availability of P
fertilizers in most soils
Which of the following is true about soil organic matter ?
A) The great majority of soil organic matter is > 100 years old while a
small fraction is younger than 2 years old.
B) The great majority of soil organic matter is younger than 10 years
old while a small fraction is > 100 years old.
C) Approximately 50 % of the N in most soils can be found in soil
organic matter.
D) Most molecules of soil organic matter have positively charged
surfaces.
1. C
2. A are you talking about plant parasitic nematodes or beneficial
nematodes? If you are talking about beneficial, then I would say answer - B
3. D
4. C
5. B Is this a multiple answer question? I guess that 50% or more of the
water insoluble nitrogen is in OM. OM particles do have a negative charge,
increasing the cation exchange capacity of a soil but this usually happens as
the OM becomes a humus, not a raw material. Doesn't the difference between
answer A & B depend on the climate, topography, moisture and
agricultural/management practices?
Joel Brooks Gruver wrote:
> How many of you are ready to become
> crop consultants ?
I don't know if I am ready.
