Directly
http://www.farmbuy.com/
Whether you are considering this endeavor from a business or lifestyle perspective, make sure you actually try it out (e.g. get a job on the farm) first before you pull up stumps and dive head in...
Yeah, if you have no experience you certainly should try before you buy.
Many people ridicule farmers and farming as next to poverty and backward. Certainly, it can be hard work and poor returns at times, but certainly not backward, at least in the sense that all you do is buy some acerage and plough and plant a crop or run some livestock.
Many blue and even white collar employees would be surprised at the amount of knowledge, expertise and technology to successfully manage a rural production enterprise these days.
One way to invest in farming land is to marry a farmer!
... or form close trustworthy relations with someone in the industry where you can become a partner in some way offering different but complementary skills or services, eg business administration, marketing, logistics etc.
Seriously, I know of a few cases where one partner was a tradie, 'professional' or business owner who kept their day job as security for bad seasons, and were often better able to capitalize on good seasons and increase their wealth. In these cases, like small business generally, they all put in the work and hard yards day, night and weekends when it is needed.