For some crops, the fastest and simplest way to clear a field and get it ready for the following year's planting is to burn it.
Last fall, I came across what may be the largest such burn I've ever
seen. It may have just been the fact that this fire was set at dusk, but I was drawn to it from, literally, more than 10 miles away and snapped some photos.
The flames appeared somewhat unattended, but they did were under control -- at least while I was there.
Despite the telephoto effect, the house and trees were never in any imminent danger.