For some reason those boxes are always hard to find in the spring. Soil sampling is also a favorite pastime after harvest. The ground is soft after some rain, the crop is gone and it's a great chance to get out and enjoy the fall colours. This may clarify if the problem is or isn't fertility and your options in dealing with the problem. Soil sampling now will also give you a head start on next years cropping program.
Many growers are also hard at manure application.
It's time to get things cleaned up before winter. One concern with fall application of livestock manure is runoff and leaching of nutrients. In many instances the crop has been harvested from the field where the manure is applied and there are only weed escapes to absorb the nutrients. If it fits into your management program, incorporation of the manure will reduce the possibility of manure runoff and increase the possibility of nutrient tie-up in the soil. Maintaining increased distances from surface watercourses such as drainage ditches, streams and grass waterways will also reduce the risk of off site movement of the manure nutrients.