I really liked this extract, but not sure I can add much new constructive criticism to what has already been said. Rick's observations about the order of the elements resonated with me - I hadn't spotted this aspect when I read your extract, but then when I read his comments, I was like, "Oh yeah! Doh!"
I really liked the way you presented the contrast between the narrator and her brother who "...looks after the farm like a precious heirloom", whereas she herself (a city girl) lacks all of the necessary knowledge and understanding to do justice to it. This, coupled with their recounted conversation and the final two short paragraphs, effectively highlight what I suspect may be key ideas in the novel ('roots' and 'value'). I loved the line, "There is no currency to value it with."