We are often asked about applying our products on snow-covered or frozen ground. While it may seem intuitive that products should not be applied to frozen ground, in general, applications can be made during late fall or winter and have similar considerations as other times of the year, such as water and ground conditions.
When determining if conditions are adequate to apply SO4 and 98G, keep these considerations in mind.
Potential for water runoff
Water influences movement of surface applied inputs. When water has potential to runoff and not infiltrate, then perhaps applications should be delayed.
Late fall and early winter before the ground is completely frozen can be a good time to make applications. As long as there’s not a substantial amount of snow on the ground (less than 6 inches), applications of 98G and SO4 can still be made. If snow comes early, there’s potential that it will slowly melt and start breaking down the product, which will help disperse the particles of the pellets and make them more effective come spring.
Even if the ground is completely frozen, applications can be made before too much snow accumulates. An extremely wet spring with multiple, heavy rain events can lead to water, and thus, product runoff and off-target effects, so paying attention to long range forecasting can help inform application decisions.
Slow snow melt and ground thaw is the best case scenario for products applied on frozen ground. Even if there is some runoff, it’s not likely that all of the product will be taken from where it was applied.
Heavy or primary tillage (moldboard or chisel plow, ripper) is not a recommended practice after application of 98G or SO4. Application should be delayed until after these tillage practices have already occurred, due to non-uniform depth of application and the likelihood that the pellets will be placed too deep in the soil profile to affect meaningful pH adjustment.
If ground is not completely frozen, then there’s still a chance for the product to start working its way into the ground. SO4 should always be surface applied and left to release its nutrients from the surface, so if some tillage is expected after the application, it may be wise to delay application until spring after ground work has been completed. 98G can be incorporated via surface preparation, so the same considerations do not apply to both products in this case – incorporation can also reduce runoff potential for 98G.
Slope of the field should also be considered; relatively flat ground is less susceptible to runoff events and will have more leeway with late fall and winter applications.
To summarize, frozen ground applications are acceptable if snowpack and slope are minimal – however, the risk of excess water in the spring and significant runoff are always present.