Grady County Ag Agent Brian Hayes wrote a good blog post about proper Soil Sampling on the Grady County blog he manages. Soil pH is the most important component of soil fertility since pH is the basis for what nutrients are available. Below is a graph of nutrient availability.
All of our micronutrients become more available as pH decreases, but you lose most primary and secondary nutrients in this case. Somewhere between 5.5 to 6.5 a good range for all nutrients to be available. Of course some crops can withstand lower pH than others. For example, a common nutritional difficiency of pecans is “Rosette” which is zinc deficiency. On the contrary, peanuts are prone to a zinc toxicity. When pH falls, zinc becomes more available and a field of peanuts will show zinc toxicity (Below).
After harvest is also a good time to do nematode samples if there has been an issue in a field. We’re getting toward the end of our recommended sampling time for some crops. Here’s the UGA nematode recommendation chart from the 2014 UGA Pest Management Handbook: