What happens at field capacity?

• A. Macropores drain while micropores remain full of water
• B. All pores dry out
• C. Macropores fill with air
• D. Micropores drain first

Answer: (A)

Field capacity is the moisture condition of soil after gravity-driven drainage has stopped. Water in soil is held by capillary forces in the pore spaces. The larger pores, or macropores, drain first because gravity pulls water out more easily from these bigger pathways. The smaller pores, or micropores, retain water more strongly due to higher capillary suction, so they stay filled. Therefore, at field capacity the macropores are drained (air-filled) while the micropores remain full of water.