What does the term runoff refer to in horticulture?

Runoff in horticulture refers to the movement of water over the soil surface. This process occurs when rainwater or irrigation water is unable to infiltrate the soil due to saturation, compaction, or a lack of vegetation cover. As a result, the excess water flows across the ground, often carrying with it nutrients, soil particles, and potential pollutants. Understanding runoff is crucial for managing water resources effectively, as excessive runoff can lead to erosion, loss of soil fertility, and contamination of nearby water bodies.

The other options highlight important aspects of water management but do not encapsulate the specific definition of runoff. Water absorbed by soil is part of the infiltration process, water released from plants pertains to transpiration, and water used in irrigation refers to the controlled application of water to crops, all of which contribute to the overall water cycle but do not describe runoff directly.