Philip Small has been doing a loose series of posts at Transect Points dealing with some of the nitty-gritty aspects of modern agriculutre, beginning with German science workshop news critical of precision agriculture performance and Science and nitrogen use efficiency and continuing through Precise common sense II. I have a couple of posts-in-progress that refer to them - and may finish them in future - but you can profit from just reading them now.

I found the most recent posts which investigated the net benefits of precision agriculture useful. Bottom line: it depends.

The technology is not affordable if there is little variability in the soil, or if a crop (corn, soybeans) does not respond as well to in-season management.