Soil Test to Know Alfalfa Fertilizer Needs

“I know I sound like a broken record because I say it’s always best to start with a current soil test,” said Tim Stelter, location manager at Federated’s Osceola location, but it’s true. A current soil test and knowing what crop removal took from the soil are the two critical pieces of information necessary for making fertilizer recommendations.

Alfalfa removes large amounts of both potassium and phosphorus from the soil. Soil pH and phosphorus are both critical factors when getting a new alfalfa stand established (see article above). Soil tests are the only sure way to know what fertilizer the next crop needs.

“Manure, if available,” said Stelter, “is an excellent source of sulfur and phosphorus,” adding that it can “make anyone appear to be an above average farmer!” But when manure isn’t available, commercial fertilizer supplies the needed nutrients.

The best time to fertilize alfalfa is after the first and last cuttings, “and don’t forget that even grassy hay fields require proper fertilization,” said Stelter. Boron and nitrogen are mobile in the soil, so apply boron to alfalfa early in the year; in the case of grassy hay, apply nitrogen early in the year. Having the phosphorus and potassium levels well balanced is important for both crops to help improve yields and stand longevity.

Stelter said Federated has offered blendable Gypsoil® for the last couple seasons. “The term 'no-brainer' comes to mind when discussing Gypsoil and alfalfa fertility. The sulfur in Gypsoil is a longer, slower release formulation than other forms of fertilizer and alfalfa loves the calcium in it.”

Gypsoil is also pH neutral, which means it doesn’t lower the pH as other fertilizers can. Elemental sulfur is another good option for slow-release sulfur, and it is well suited for fall application.

Talk to your Federated Agronomist about Gypsoil or other fertilizer options for your alfalfa or grassy hay fields this fall.