Describe the basics of nutrient cycling in rangelands, including the roles of litter, soil microbes, and plant uptake.

• A. Plants take up nutrients; litter decomposition returns nutrients; microbes mineralize organic matter, cycling nutrients back to plants
• B. Animals produce nutrients
• C. Water dissolves all nutrients without soil microbial involvement
• D. Nutrients are fixed and never recycled

Answer: (A)

Nutrient cycling in rangelands is driven by three interconnected steps: plants take up nutrients from the soil, litter from plant material decomposes to release those nutrients back into the soil, and soil microbes mineralize the organic matter to make nutrients available again for plants. Litter acts as the reservoir of organic matter and nutrients; as soil microbes—bacteria and fungi—decompose this material, they convert nutrients from organic forms into inorganic forms that plant roots can absorb. This mineralization process continually replenishes the soil with nutrients, which plants then take up, sustaining growth and restarting the cycle. In this system, microbes are essential players, linking dead plant material back to living plants by transforming nutrients into usable forms.

The other ideas don’t fit because nutrients aren’t simply produced by animals, and the cycle relies heavily on microbial processes and soil organic matter rather than nutrients being dissolved away only by water. Also, nutrients aren’t fixed forever; they are released, taken up by plants, stored in litter, and continually recycled.