Should I fertilize my farm lawn in the fall? For many years, turf specialists recommended a late-fall “winterizer” fertilizer application, which was applied in late November. But new research has ended that recommendation.
Fall weather is characterized by lower light intensity, shorter day length and cooler temperatures. These environmental changes reduce the amount of water used by grass plants, which decreases the “sucking” force of leaf-blade water loss to move nitrogen fertilizer from turfgrass roots and into the plants.
This slowing of plant processes reduces fertilizer uptake efficiency and increases the risk of nitrogen loss to the environment during winter. In the best-case scenario, N applied in late fall stays in the soil and causes a tremendous growth flush next spring.
In the worst-case scenario, N either leaches downward through the soil or through surface runoff into surface water such as creeks, lakes and ponds where it causes algae blooms next spring. Leaching can occur at any time of year, but the potential is highest with late-fall fertilizer applications.
No slow release
Slow-release fertilizers, many of which require soil microbes to break down their outer pellet coating and make the inner nutrients available for plant uptake, also lose effectiveness in late fall as the soils cool and microbial activity slows.
For these reasons, the recommendation for a late-fall application of slow-release fertilizer has ended. If your grass is dark green, healthy and thick, no additional fertilizer is needed in late fall.
Save the fall fertilizer product for application next spring — it’s better for the environment, your turf and your wallet. As long as the bags are kept dry, they will be fine for use in spring.
If the turf is newly established, possibly following new home construction, off color or low vigor, a late-fall application may still be beneficial. Make a light application of a water-soluble product, 0.5 pound of N or less, before the end of October.
Learn more at turf.unl.edu.
Browning is a Nebraska Extension educator in Lancaster County.