Here’s another way to view the role of crop residue on phosphorus (P) availability in continuous corn:
After corn harvest, only 22% of the crop residue—leaves, tassels, second ears and silks—has a carbon to P (C/P) ratio below 200:1, resulting in a net gain of available P through mineralization. Another 10%, the ear sheaths, has a C/P ratio between 200:1 and 300:1, so P is neither gained nor lost. But 68% of the residue—stalks, cobs, husks and shanks—has a C/P ratio greater than 300:1, meaning there will be a net loss of P through immobilization early in the growing season.
"The phosphorus that is immobilized by the microbes is not lost from the soil," says Farm Journal Field Agronomist Ken Ferrie. "But because there is a temporary net loss of phosphorus, we must apply fertilizer in the spring to decompose the residue and make phosphorus available to plants."
Learn and Profit from Nutrient Navigator
The Nutrient Navigator series focuses on efficient, environmentally sound management of nutrients. The goal is to provide practical knowledge that helps drive yields and profits higher.