Compared to the rest of the soil, the rhizosphere is kept relatively sterile by the action of plant roots.
Indicate whether the statement is true or false
Question 2Polysaccharides produced by soil microbes and similar synthetic polymers applied to soils are largely responsible for the crusts that form when rain follows tillage.
Indicate whether the statement is true or false
Question 3For any soil, the bulk density is always lower than the particle density.
Indicate whether the statement is true or false
Question 4Where conditions are favorable, earthworms are known to add several hundred kg/ha of several important nutrients to the soil system.
Indicate whether the statement is true or false
Question 5This (these) group(s) of microorganisms usually predominate(s) in sandy, acid soils.
A) actinomycetes
B) bacteria
C) fungi
D) both A and C
E) all of the above
Question 6Disease suppressive soil often results from:
A) fumigation with a volatile chemical.
B) heating the soil by natural solarization or steam heat.
C) adding organic materials to the soil that stimulate diverse microorganisms.
D) repeated tillage to keep the soil bare for at least one full year.
E) all of the above
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