Fall-Applied K Promotes Winter Survivability

An alfalfa crop removes tremendous amounts of potassium (K) from the soil –typically about 60lb K2O/ ton of alfalfa. Naturally, those nutrients must be replaced to ensure the future success of the stand.

A fall application of a high-quality K source, such as Protassium+® premium sulfate of potash is an ideal solution for several reasons.

Adding Protassium+ sulfate of potash (0-0-50-17S) in the fall effectively prepares the plants for dormancy by increasing their storage of soluble carbohydrates in the roots, which is a major step to promoting the longevity and consistent nutrient value of your stand in following years.

 “For established stands, the critical time when alfalfa needs the most P and K is usually in preparation for winter,” says Dorivar Ruiz Diaz, a Kansas State University Extension nutrient management specialist. “To boost the winter hardiness of the crop, a good supply of P and K needs to be added before the critical fall growth period. Early fall fertilization when there is still some plant growth (four to six weeks before dormancy) is usually more effective in increasing winter survival, because nutrients are supplied in time for adequate uptake.”1

In addition to encouraging winter hardiness and standability, applications of Protassium+ SOP in the fall have been shown to stimulate the uptake of other nutrients, improve disease resistance and maximize overall plant function.

At harvest, having greater cutting frequency and stand age increases the potential for winter damage when fall cuttings are taken.

Older stands are more susceptible to winter injury due to a higher likelihood of disease presence and more physical damage to the plants2. In those cases, sufficient potassium becomes even more important.

Apply the right K.

Protassium+ SOP is the best choice of a potassium fertilizer because it has virtually no chloride. Some K sources, such as muriate of potash (MOP), are very high in chloride. Accumulated salts in the soil can affect the root function of alfalfa plants and inhibit crop growth. Therefore, applying a low-chloride product can eliminate that concern. Protassium+ premium fertilizer also provides 17% sulfur in sulfate form, making it immediately available for plant uptake prior to dormancy.


1 “Meet Alfalfa’s Fertility Needs”; Hay & Forage Grower

2 Alfalfa Management Guide (USDA)