Smooth brome requires annual fertilization for optimum production.
Fall is an ideal time to plan for fertilizing cool-season perennial grasses in improved pastures, such as smooth brome.
Particular attention must be paid to nitrogen, phosphorus and pH. Information on fall soil testing of hayfields and pastures is discussed this week in a separate article by Alicia Boor, Agriculture and Natural Resources agent in the Cottonwood Extension District’s Great Bend office.
In this article, I will address fertilization of smooth brome pastures and hayfields. Balanced fertility is essential. For example, adding nitrogen will not produce optimum yields if phosphorus is low. Soils low in phosphorus can limit plant and root growth.
Fertilizer should be applied by broadcasting in the fall or before spring growth begins. This article discusses how nitrogen source and application timing can affect forage quality and yield.
Nitrogen source — Nitrogen management is critical for optimum smooth brome production.
Several nitrogen sources are available: liquid nitrogen solutions, urea, ammonium nitrate and anhydrous ammonia. Anhydrous ammonia is not extensively used on permanent pastures because application is difficult.
Research generally has shown little difference among nitrogen sources under most conditions.
When urea fertilizers, including liquid nitrogen, are applied to moist soils covered with grass residue, an enzyme called urease can break down the urea into ammonia gas, which is lost to the atmosphere (ammonia volatilization).
This can occur fairly rapidly in the spring when moist conditions are followed by warm temperatures and rapid drying, with no rain to move the urea into the soil. If urea is applied from November through February, when temperatures are cooler, volatilization losses should be minimal.
Application timing —
If brome is fall-grazed, the yearly nitrogen application should be split. If adequate soil moisture is available for good growth in late August and early September, apply all phosphorus indicated by a soil test plus 20 to 30 pounds of nitrogen per acre. Grazing can resume after the fertilizer prills or pellets have dissolved, which reduces risks to livestock. Before the soil freezes in November or December, apply the remaining nitrogen recommended for haying or grazing. Split or late-fall applications generally result in earlier green-up in the spring. To minimize loss, do not apply fertilizer to frozen soil.
Spring applications should be made as soon as the soil thaws and are acceptable for spring-only grazing or haying. Fertilizer needs to be applied in the fall or early spring to allow sufficient time for incorporation to benefit forage production.
Fertilizer rates (nitrogen and phosphorus) — Fertilizer rate recommendations ideally should be based on soil test values and yield goals for established stands of smooth brome. When brome is to be used for hay production, excessive nitrogen may cause lodging and reduce the amount of harvestable hay.
The Cottonwood Extension District has soil sampling hand probes that can be checked out at no charge from our offices in Hays and Great Bend. Before coming to pick one up, call to make sure one is available.
Stacy Campbell is an Agriculture and Natural Resources agent for the Cottonwood Extension District. Email him at scampbel@ksu.edu or call the Hays office at 785-628-9430.
