Precision Agriculture is About Efficiency
With corn harvests complete, growers are reviewing their yield data to see areas of the field that may need management modification. Grid sampling of soil in the fall helps to see where pH and nutrients may be off. Seeing yellow (or red) in the yield monitor is another flag.
Regardless of what technologies or tools you have, collect data each year and take time to evaluate what you changed each year. Certainly the weather plays a big role too. Measuring nitrogen applied versus bushels of grain result is on of the easier ways to calculate efficiency. Otherwise known as Nitrogen Use Efficiency (NUE) or Partial Factor Productivity (PFP), growers are encouraged by various state and fertilizer industry representatives to wisely steward their resources.
Check out this link to learn more: http://www.ipni.net/publication/bettercrops.nsf/0/99FE13C6C096A13385258124006FD554/$FILE/BC-2017-2%20p10.pdf