Final answer:
Field efficiency is likely highest for spraying due to faster coverage, especially in monoculture fields. Crop rotation and no-till farming are practices associated with sustainable agriculture, which differ from conventional agriculture's focus on maximizing yields through intensive methods.
Step-by-step explanation:
The operation with the highest field efficiency among combining, planting, spraying, and plowing would likely be spraying. Spraying allows for more consistent coverage and can often be completed more quickly than the other operations, especially when considering large fields of crops such as a 100-hectare soybean field, which is an example of a monoculture. A practice that allows farmers to improve soil fertility, diversify their crops, and reduce pesticide costs is crop rotation, which involves alternating the types of crops grown in an area with each season or year. This practice helps break the cycle of weeds, insects, and diseases.