One booking in a year with a 5-star review suggests your guests enjoy the experience once they find you. The challenge may be visibility rather than quality.
I host a farm stay as well. Even with a well-rated listing, I notice there are slack periods during the year. On average, I receive 4–6 bookings a month, but demand is definitely seasonal.
A few things that have helped me are:
Refreshing photos and the first few lines of the listing regularly.
Keeping the calendar updated and using competitive pricing during quieter periods.
Offering discounts for weekdays or longer stays.
Responding quickly to every inquiry.
Sharing the listing on social media and local travel groups to drive additional traffic.
Don't get discouraged after just one booking. Farm stays appeal to a niche market, and it can take time for Airbnb's algorithm to gain confidence in a newer listing. Continue collecting excellent reviews, keep your listing active, and make small improvements regularly. I hope you see many more bookings in the coming months. Good luck!