Soil Air, Moisture & Temperature is one of 9 topics in the Grade 11 Agricultural Sciences CAPS syllabus, covered across 3 lessons on Study Vault. Below are real practice questions from this topic with full worked answers.
Sample practice questions
Easy
1. Where does soil air occupy space within the soil?
In the macro pores, when they are not filled with water
Only inside soil aggregates themselves
Dissolved entirely within soil water
Only in the topmost 1mm of soil
Answer: In the macro pores, when they are not filled with water — Soil air occupies the macro pores (larger pore spaces) of soil whenever those pores are not filled with water.
Easy
2. Name the process describing the continuous exchange of gases between soil and the atmosphere above it.
Answer: soil aeration — Soil aeration is the continuous exchange of gases between the soil and the atmosphere, replenishing oxygen and releasing excess carbon dioxide.
Medium
3. How does the composition of soil air typically differ from atmospheric air?
Soil air has lower oxygen and higher carbon dioxide concentration
Soil air has higher oxygen and lower carbon dioxide concentration
Soil air and atmospheric air always have identical composition
Soil air contains no gases at all, only water vapour
Answer: Soil air has lower oxygen and higher carbon dioxide concentration — Because plant roots and soil organisms consume oxygen and release carbon dioxide through respiration, and gas exchange with the atmosphere is restricted by solid soil particles, soil air generally has lower oxygen and higher carbon dioxide concentration than atmospheric air.
