Question

select all the correct answers. the adoption of which two practices helped to increase the amount of food produced per unit area of farmland? four-field crop rotation the application of chemical pesticides the use of steam-powered tractors land irrigation using steam-powered pumps selective livestock breeding

Explanation:

• four - field crop rotation: This practice helps in maintaining soil fertility, as different crops in the rotation have different nutrient requirements and contributions. By rotating crops like wheat, barley, turnips, and clover, the soil can retain nutrients better, leading to higher yields per unit area over time.
• selective livestock breeding: Selective breeding of livestock can improve the quality and quantity of animal - based food products (like meat, milk, etc.). Also, improved livestock can have better grazing habits or contribute to better manure for the soil, which in turn can enhance crop yields per unit area of farmland.

The application of chemical pesticides is more about protecting existing crops from pests rather than directly increasing the production per unit area in the same way as the two selected practices. The use of steam - powered tractors and steam - powered pumps for irrigation are more about mechanization and expanding the area under cultivation or improving irrigation efficiency in a different sense, not as direct in increasing production per unit area as the two chosen practices.

Answer:

A. four - field crop rotation
E. selective livestock breeding