What does "soil amendment" refer to?

Soil amendment refers to any material added to soil with the aim of improving its physical or chemical properties. This can include various substances such as organic matter, lime, gypsum, or fertilizers which work to enhance aspects like soil structure, nutrient content, water retention, and microbial activity. By adding these materials, the soil can become more productive, supporting better plant growth and promoting overall soil health.

The other options do not accurately describe soil amendments. Adding water to soil is a vital practice for irrigation but does not constitute an amendment. Techniques for planting crops relate more to agricultural practices rather than modifications to soil properties. Meanwhile, natural soil formation encompasses processes that develop soil over time due to environmental factors, rather than the intentional introduction of materials to improve existing soil conditions.