Bitcoin is just money. The only comparation or correlation between agriculture and bitcoin I could think about is the same when we talk about fiat and agriculture: you work as a farmer, grow your crops, sell it and are paid. So you use part of your payment to re-invest in the land and keep this cycle of work going on. You could do the same with bitcoin, instead of using fiat. Actually I think that is all and the same is valid for any other profession.