What role do residues play in the soil ecosystem?

Residues play a crucial role in the soil ecosystem by contributing organic matter and enhancing nutrient cycling. When plant materials and other organic residues decompose, they add essential organic matter to the soil, which improves soil structure, water retention, and aeration. This organic matter serves as a habitat and food source for a variety of soil organisms, including bacteria, fungi, and macrofauna, all of which contribute to the breakdown of organic materials. As these organisms break down residues, they release nutrients that become available to plants, facilitating healthy plant growth and promoting biodiversity.

The enhancement of nutrient cycling is particularly significant because it helps in replenishing the nutrients that crops take up during their growth. This cycling process ensures that essential elements like nitrogen, phosphorus, and potassium are returned to the soil, making them accessible to future crops.

In contrast, other aspects mentioned in the options do not accurately describe the positive impact of residues in the soil, such as decreasing organic matter levels, preventing water retention, or feeding pests exclusively. Instead, residues are fundamental to maintaining the health and fertility of the soil ecosystem.