Many hay producers have completed the first cutting of the year. One of the two best times to topdress maintenance fertilizer on hay is right after the first cutting, Ohio State University Extension advises. The other top choice is in early fall. Hay crops will remove about 50 pounds of potassium and 12 pounds of phosphorus per ton of dry hay harvested.

Fertilizer can be topdressed on hay or pastures at any time during the growing season, but right after the first cutting and early fall provide times when the soils are usually firm enough to support fertilizer spreading equipment and the nutrients are applied to actively growing plants when they are most needed, according to OSUE.

A recent soil test can be the guide for what nutrients to apply and how much. If nutrient deficiencies are suspect, then tissue tests can be helpful in diagnosis along with the soil test values. Where high rates of phosphorus and potassium are recommended, there is an advantage to splitting the application, with half applied now after the first harvest and the remainder applied in the fall.

OSUE has an Excel tool to help determine the right rates to apply based on a soil test report. The OSU Fertility Recommendation Calculator and a user guide are available at forages.osu.edu.

Among those recommendations, OSUE says strategic applications of nitrogen might be needed on pure grass hay and pasture stands. Moderate amounts of nitrogen (30 to 50 pounds of N per acre) can be applied in June through early July after the first cutting, or after the spring flush and reproductive stages of the cool-season grasses are over in pastures.

This application will stimulate summer hay growth or pasture grass growth that can be stockpiled for use when pastures slow down later in the season. This application should be limited in acreage for pastures, based on how much grass growth is needed to carry the herd or flock.

Be aware of the forecasted weather conditions when applying nitrogen, OSUE advises. Moderate rainfall will incorporate most sources of nitrogen when topdressed, but when predicted rainfall exceeds 1 inch, it increases the potential loss of nitrogen into downstream water sources.

Source: OSUE, which is solely responsible for the information provided and is wholly owned by the source. Informa Business Media and all its subsidiaries are not responsible for any of the content contained in this information asset.