Visualizing a farm through a logo is a tough task but not impossible. This is because there are thousands of farms in any given rural area. Where there's one farm, there would likely be many others not too far away. Hence, you have to be careful in distinguishing your business from the rest. To this end, a business logo could come in very handy in building up your brand identity and familiarity.
The colors of a logo associated with farming are usually those that are found in nature. These include green, yellow, and brown for the most part. Red and blue may also be used to signify fruit and water respectively. Whatever colors you use should be reflective of your specific farm and the main business going on there. For instance, if you're growing strawberries, the color red would definitely have to be included in your logo.
The font used in your farm logo should be easy to read, but reflective of your business attitude and your target audience. The same goes for the design style you choose. If your farm is a somewhat serious organization and caters mainly to business clients, you should have a straightforward font with no curls and a sensible, non-nonsense designs. If you're a farm that's focused on providing fun activities for children you could have a more playful font and design.
No matter which font, picture, or design you go with, remember that your logo should signify a farm niche. Elements that symbolize luxury probably shouldn't come into play here, like the color purple or a glittering jewel. You should also avoid limiting yourself to a specific item, since farms can diversify and produce new products within a few years.
It's best if you consult an experienced logo designer for your farm logo decisions. They would be able to guide you on what seems best for your farm in terms of its logo.