As fall fertilizer plans take shape, it's time to make sure soil sample results are current. "If you don't have a good and recent soil sample," said Kevin Carlson, Federated's senior agronomist, "it's time to get one."
As repeatedly noted in this Agronomy Update, the universities recommend soil tests every four years. "But I'd recommend more," said Carlson, "especially in today's economic crop production picture."
"Twenty bucks and change for a soil sample is pretty cheap," said Carlson, especially when nutrient and lime application needs are based on the results. It's time to dig out field records and see what fields have been tested and when.
Soil sample tests are the starting point. Carlson said, "The soil analysis is an important layer of information you need to start a nutrient management plan." The soil test analysis provides nutrient content, potential nutrient availability, soil texture and CEC capacity, nutrient balance (one in relation to another), and active soil pH levels.
For growers who choose to do soil sampling on their own, Carlson highlighted the need to take samples at a consistent six-inch depth. The soil test analysis is calibrated to a six-inch depth (note the six-inch mark on the probe in the photo).
For composite samples, take 14-16 samples (probes) per 40-acre field. Splitting that into two 20-acre composite samples is even better, Carlson advised. Once submitted for analysis, soil test results take about a week to get back.
Accurate sampling is where it all starts for making fall - and spring - nutrient decisions. Federated Agronomists are ready to help: "Our GPS composite or grid sampling is a great service that is repeatable; we can get back to the exact same spots [to test the soil] one, two, or three years from now," said Carlson.
Contact your Federated Agronomist for more information on soil sampling.