Which of the following is not the names of soil structures?
A. blocky structure
B. porous structure
C. granular structure
D. columnar structure
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When the soil pH is 8.0, the availability of ( ) is the lowest.
A. nitrogen
B. sulphur
C. molybdenum
D. phosphorus
In the profile of natural soil, the C horizon usually refers to ( ).
A. litter layer
B. compaction layer
C. parent material layer
D. deposition layer
When the same amount of fertilizer is applied into sandy soil and clayey soil, the fertilizer efficiency is higher in sandy soil. One of the reason for this phenomena is that ( ).
A. The cation exchange capacity of sandy soil is larger, so that the cation saturation and availability are lower
B. The cation exchange capacity of sandy soil is lower, so that the cation saturation and availability are higher
C. The cation exchange capacity of sandy soil is lower, so that the cation saturation and availability are lower
D. The cation exchange capacity of sandy soil is larger, so that the cation saturation and availability are higher
When the pH of kaolinite suspension is increased, the absolute number of variable charges ( ).
A. does not change
B. decreases
C. increase or decrease
D. increases
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