Provide your best answer for the following question. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The question is: After fields of crops are harvested, parts of the plants remain on the ground. For many years, farmers have mixed these plant remains into the soil. Which most likely results from this practice?
Soil enrichment.