Hopefully there are no soybeans still in the field at this point in Illinois. Even the double crop soybeans should be out by now. So soybean management is done for the season. And while you might thinking of heading south to sunny shores for the winter, take some time to start preparing for 2016.
Setting the stage for yield really begins with the soil—which begins with soil sampling and a measurement of soil health. Fall is the time to pull soil samples. Soil is fit for sampling and you can make applications of dry materials without compacting the soil.
A conventional soil test will not only give you the pH, organic matter, and nutrient levels of a field, but most labs also provide crop specific recommendations for nitrogen (N), phosphorus (P), potassium (K), calcium, magnesium and sometimes micronutrients. While a lab can test for sulfur (S), this test is considered unreliable and not a good predictor of making a sulfur application.
The most important measure is soil pH. You want pH to be between 6.2 and 6.5 and if below, you lime. Sometimes you will see spots in a field that measure 7.2 or 7.6, and while a high pH can impact nutrient availability it is not a toxicity issue for rhizobia and root tips or hairs. It is also good to track organic matter. Growers who use tillage and a corn and soybean rotation will maintain organic matter levels between 2 and 3 percent generally. However, if you grow more corn in your rotation and plant cover crops or include wheat, you can push that between 3 and 4 percent. A healthy soil requires a near neutral pH, non-saline and non-sodic soil, and plenty of organic matter and nitrogen for the bugs to go to work.
Soil should be tested frequently. If you do composite sampling, sample every year. If you grid or zone sample, pull cores every 3 or 4 years. Pull samples from six or eight inches, but consistently use that same depth. Avoid problem spots as they do not represent the field; however, you can sample problem spots to diagnose the cause.
Soil testing generates trend lines over time. By monitoring soil tests you can see how cultural practices are impacting the soil and nutrient availability. Measuring organic matter test, base saturation and cation exchange capacity (CEC) can tell you if the quality of your soil is changing, which impacts productivity.
Today you can run the Solvita® soil respiration test as well as a soil health test. Do these in addition to conventional soil testing to really start to understand the health of your soil and then monitor the health of your soil every time you pull soil samples.
Agronomist Dr. Daniel Davidson posts blogs on agronomy-related topics. Feel free to contact him at firstname.lastname@example.org or leave a comment below.