Waterwheels benefit the farming process by providing a reliable and efficient source of mechanical energy for various tasks, such as irrigation, grinding grain, and processing crops. This leads to increased agricultural productivity in several ways:

1. **Irrigation**: Waterwheels can help deliver water to fields, ensuring crops receive adequate moisture, which is crucial for growth.

2. **Grain Processing**: They can power mills for grinding grain, making it easier to produce flour and other essential food products.

3. **Labor Efficiency**: By mechanizing tasks that would otherwise require manual labor, waterwheels allow farmers to operate more efficiently and increase their output.

4. **Sustainable Energy**: They harness renewable water energy, reducing dependence on fossil fuels and increasing sustainability in farming practices.

As for the second part of your question, various factors can contribute to agricultural productivity. For example, you could fill in the blanks with terms like "technology advancements," "crop rotation strategies," or "soil management practices."