August 31, 2014

Is a Potassium Deficiency Robbing Your Alfalfa?

Potassium is one of the three essential macronutrients and is vital to a fully optimized alfalfa crop. Studies show that a potassium deficit may be more prevalent than most realize.

The deficiency has been especially pronounced in dairy acres. Understanding the relationship between alfalfa and potassium helps shed some light on the issue. The crop has a high potassium removal rate at approximately 60 pounds per ton of alfalfa yield. This is attributed to the fact that when alfalfa is harvested, the entire above ground portion of the plant is removed. Other crops like corn and soybeans typically remove just the grain and leave much of the potassium behind in crop residue. This potassium may eventually return to the soil as the crop residue breaks down. Cutting or harvesting Alfalfa typically leaves little or no residue and thus more potassium is removed from the field.

This consistent demand on potassium can have a significant impact on alfalfa crops, especially with three to four cuttings in a season. A deficiency presents itself through yellowing of plants, or it may be identified by a susceptibility to water stress.

Sampling for potassium can be a valuable part of a crop management plan. By replenishing this essential nutrient, growers could improve resistance to drought, disease, and pests, potentially leading to improved stands and yields.