To increase soil organic matter levels, what practice must be markedly reduced or eliminated?

To increase soil organic matter levels, significantly reducing or eliminating tillage is essential. Tillage disrupts soil structure and can lead to the breakdown of organic matter. When soil is tilled frequently, the natural microorganisms and fungi that contribute to the decomposition of organic materials are disturbed, leading to the release of stored carbon in the form of carbon dioxide. This process not only reduces the amount of organic matter in the soil but can also lead to diminished soil fertility over time.

By minimizing tillage practices, the soil environment becomes more conducive to the accumulation of organic matter. This allows for better retention of soil structure, moisture, and nutrients, creating an ecosystem where organic matter can thrive and be built upon through organic inputs such as crop residues, cover crops, and compost.

Other practices, such as crop rotation, fertilization, and pesticide use, do not have the same direct impact on soil organic matter levels as tillage practices do. In fact, crop rotation can often enhance soil health and organic matter levels by providing diverse root structures and plant residues. Fertilization can also support plant growth, leading to more organic material being returned to the soil.