Compaction of soil in a garden has which of the following effects on plants?

Compaction of soil in a garden significantly influences its physical properties, notably affecting how air, water, and nutrients interact within the soil. The correct choice highlights that compaction decreases aeration, decreases infiltration, and increases runoff.

When soil becomes compacted, the spaces between soil particles, known as pore spaces, are reduced. This diminishes aeration, which is essential for plant roots to absorb oxygen necessary for respiration. Limited aeration can lead to root stress and hinder plant growth.

Moreover, decreased infiltration is a consequence of compacted soils since the soil's ability to absorb water is impaired. As a result, instead of soaking into the ground, water is more likely to run off the surface. This increased runoff can lead to erosion and a loss of valuable topsoil, further impacting garden health.

Thus, the correct answer reflects the real-world consequences of soil compaction on plant health and water management in gardening environments, highlighting the essential need for maintaining healthy soil structure.