School's back in session and it's time to harken back to chemistry class to determine what important elements are needed in the fields. What comes into play for next year's crops: S, P, K, Ca, N?

Fall application of any fertilizer or lime requires knowing what's already in the soil. As Federated agronomists say over and over, "Take soil samples." Don't rely on samples that are more than four years old (university recommended).

Soil sampling is fastest and easiest before fall tillage when "you can drive around the fields in your pickup or on a four-wheeler, and not have to bounce across the field," said Gustafson. Plus, soils are drier in the fall, and there's less soil compaction.

With soil sample results in hand, it's relatively easy to determine the right elements to apply.

S and Ca -  Especially for growers rotating to corn in 2018, "Consider applying gypsum this fall," said John Swanson, Federated Agronomist at the Ogilvie location. "Gypsum is not a liming agent," he said, "but it does provide 21% calcium (Ca) and it is a great source of season-long sulfur (S) at 17%. Gypsum is not as slow release as elemental S, but it is not as fast and leachable as AMS, and thus is a great option for corn, but it's also good for soybeans and alfalfa, "both of which respond well to S and Ca." said Swanson.

Gypsum (more info in article below) is also great product to apply in the fall with:

P and K - By applying phosphorus (P) and potassium (K) in the fall, "the only thing left for spring is the N (nitrogen), "said Rod Gustafson, Federated agronomist at the Albertville location. "You'll also get more acres out of a spreader load come spring," he added, when only N (and probably S) needs to go down because the other elements were applied in the fall. It's a logistically wise choice.

"Fall is also the time for lime," said Gustafson. Federated does liming in the fall when there are no road restrictions and other fertilizer applications aren't pressing. Come spring, the demand on everyone's time intensifies. Apply lime in the fall and be ready for spring.

Autumn is also a good time to do grid soil sampling and move into variable rate (VR) fertilizer applications. Getting the soil maps compiled sets the stage for both VRT application in the fall and planting in the spring.

"The biggest thing [about fall fertilizer application] is labor saving," said Gustafson, who observed that growers who do fall fertilizer applications continue to do it in subsequent years, "because they see the advantage of it."

Contact your Federated Agronomist with any questions about fall fertilization, or to get started with VRT on your farm.